201_2017

I HC QUC GIA H NI

TRNG I HC CNG NGH

--------

Nguyn Quc i

PHNG PHP XY DNG

H THNG HI P TING VIT

DA TRN ONTOLOGY

KHA LUN TT NGHIP I HC H CHNH QUY

Ngnh: Cng ngh thng tin

H NI 2009

I HC QUC GIA H NI

TRNG I HC CNG NGH

--------

Nguyn Quc i

PHNG PHP XY DNG

H THNG HI P TING VIT

DA TRN ONTOLOGY

KHA LUN TT NGHIP I HC H CHNH QUY

Ngnh: Cng ngh thng tin

Ging vin hng dn: TS. Phm Bo Sn

H NI 2009

To My Family

Phng php xy dng h thng hi p ting Vit da trn Ontology Nguyn Quc i

i

Li cm n

u tin, em xin gi li cm n chn thnh nht ti TS. Phm Bo Sn. Thy

hng dn, ch bo v truyn t nhng kinh nghim gip em hon thnh kha lun.

Em cng xin gi li cm n ti TS. Bi Th Duy. Thy to iu kin thun li

v c nhng kin ng gp cho em.

Ti xin cm n cc bn Nguyn Quc t, Nguyn B t, Trn Bnh Giang,

Phm c ng. Cc bn gip , cng nh chia s nhng nghin cu ti c th

p dng trong kha lun.

Ti cng xin cm n cc bn Ng Th Tho, T Th Bch Hin, Nguyn H

Phng gip ti khi kh khn.

Cui cng, con xin gi li cm n su sc nht ti b m. B m sinh thnh,

nui dng, quan tm v chm sc cho con. Con xin cm n b m!

H Ni, 24-5-2009

Nguyn Quc i


ii

Tm tt

Hi p (question answering) l nhim v t ng tr li cu hi di dng ngn

ng t nhin. Nghin cu cc h thng hi p ang nhn c nhiu quan tm trn

th gii. Cc nghin cu hin nay s dng nhiu phng php x l ngn ng t nhin

cng vi Ontology c s dng lm c s tri thc. Nhu cu tm kim thng tin ting

Vit di dng hi p l rt ln nhng cc h thng hi p cho ting Vit cn cha

c nhiu nghin cu ng dng c th.

Chng ti gii thiu mt h thng hi p ting Vit da trn Ontology. H thng

ny c th p dng i vi nhiu min ng dng c th. Chng ti thit k mt

Ontology th nghim. S dng Ontology ny, chng ti a ra cch trch rt cu tr

li cho h thng hi p ny. Cc nh gi cho thy h thng lm vic tt khi tr li

cc cu hi c a ra.

Keywords: hi p, nh x Ontology, trch chn cu tr li.


iii

Mc lc

Li cm n ................................................................................................................................i

Tm tt ..................................................................................................................................... ii

Mc lc ................................................................................................................................... iii

Danh sch t vit tt .............................................................................................................vi

Danh sch hnh v ............................................................................................................... vii

Danh sch bng ......................................................................................................................ix

Chng 1. Gii thiu ............................................................................................................1

Chng 2. Tng quan v hi p.......................................................................................3

2.1 Tng quan v h thng hi p da trn Ontology ...................................................3

2.2 Khi nim v hi p (Question Answering QA) ...................................................6

2.2.1 Khi nim hi p ..................................................................................................6

2.2.2 Kin trc hi p ....................................................................................................6

2.2.3 Cc phng php hi p ......................................................................................7

2.3 Giao din ngn ng t nhin min ng ....................................................................9

2.4 Cc h thng QA min m ..........................................................................................10

2.5 Ontologies trong QA....................................................................................................12

Chng 3. Ontology Sesame..........................................................................................14

3.1 Khi nim v Ontology ................................................................................................14

3.1.1 Khi nim ..............................................................................................................14

3.1.2 Tng quan v Ontology .......................................................................................14

3.1.2.1 Cc thnh phn ca Ontology ......................................................................15

3.1.2.2 Cc thc th....................................................................................................15

3.1.2.3 Cc lp ............................................................................................................16

3.1.2.4 Thuc tnh ......................................................................................................17


iv

3.1.2.5 Cc mi quan h ............................................................................................17

3.2 Ngn ng Web Ontology (Web Ontology Language) ............................................19

3.2.1 OWL Ontology .....................................................................................................19

3.2.2 Mi quan h logic m t (Description logics DLs).......................................20

3.2.3 Cc dng OWL .....................................................................................................20

3.3 Sesame ...........................................................................................................................21

3.3.1 Khi nim v Sesame ...........................................................................................21

3.3.1.1 Sesame Server................................................................................................21

3.3.1.2 Kho d liu v suy lun (Repositories and Inferencing) ..........................22

3.3.1.3 Tng quan kin trc Sesame ........................................................................22

3.3.2 Ci t Sesame ......................................................................................................23

3.3.2.1 Ci t th vin Sesame ...............................................................................23

3.3.2.2 Ci t my ch Sesame ...............................................................................24

3.3.2.3 Qun tr my ch ...........................................................................................25

3.3.3 Giao din web ca Sesame ..................................................................................27

3.3.3.1 ng nhp ......................................................................................................27

3.3.3.2 Thm d liu vo mt kho d ......................................................................28

Chng 4. H thng hi p ting Vit da trn Ontology.......................................29

4.1 Kin trc tng quan ca h thng..............................................................................29

4.2 X l cu hi ngn ng t nhin ................................................................................32

4.3 Thit k Ontology bng Protege ................................................................................34

4.3.1 Thit k cc lp trong Ontology .........................................................................35

4.3.2 Thit k thuc tnh trong Ontology ....................................................................36

4.4 nh x Ontology ..........................................................................................................38

4.4.1 nh x Ontology cho cu hi n gin .............................................................39

4.4.1.1 nh x Ontology i vi loi cu hi NORMAL .....................................42

4.4.1.2 nh x Ontology i vi loi cu hi UNKN_REL .................................43

4.4.1.3 nh x Ontology i vi loi cu hi UNKN_TERM .............................44

4.4.1.4 nh x Ontology i vi loi cu hi AFFIRM_NEG ............................46

4.4.2 nh x Ontology i vi loi cu hi THREETERM .................................47

4.5 Trch chn cu tr li..................................................................................................51


v

4.5.1 Trch chn cu tr li cho loi cu hi NORMAL, UNKN_REL ..........52

4.5.2 Trch chn cu tr li cho loi cu hi UNKN_TERM ...............................54

4.5.3 Trch chn cu tr li cho loi cu hi AFFIRM_NEG ..............................56

4.5.4 Trch chn cu tr li cho loi cu hi THREETERM ................................57

Chng 5. Kt qu thc nghim v tho lun ...............................................................59

5.1 Kt qu thc nghim....................................................................................................59

5.2 Tho lun ......................................................................................................................61

Chng 6. Kt lun ..............................................................................................................62

Ph lc A ................................................................................................................................63

Ti liu tham kho ...............................................................................................................66


vi

Danh sch t vit tt

STT K hiu T ting Anh Ng ngha

1 NLP Natural Language Processing X l ngn ng t nhin

2 QA Question Answering Hi p

3 API Application program interface Giao din chng trnh ng dng


vii

Danh sch hnh v

Hnh 2.1. Tng quan v h thng hi p da trn Ontologies [2] ...................................4

Hnh 3.1. V d v lp trong Ontology [58] ......................................................................16

Hnh 3.2. V d v lp t ....................................................................................................18

Hnh 3.3. Sesame server [59] ................................................................................................21

Hnh 3.4. Kin trc ca Sesame [59] ...................................................................................22

Hnh 3.5. Cu hnh Sesame ...................................................................................................25

Hnh 3.6. Cu hnh kho d liu c sn trong Sesame ........................................................26

Hnh 3.7. Giao din web ca Sesame ..................................................................................28

Hnh 4.1. Kin trc tng quan ca h thng hi p ting Vit da trn Ontology ......29

Hnh 4.2. Kin trc ca thnh phn tm kim cu tr li ..................................................30

Hnh 4.3. Cc lp trong Ontology v trng i hc ........................................................36

Hnh 4.4. Cc thuc tnh trong Ontology v trng i hc ............................................37

Hnh 4.5. Tng quan v nh x Ontology i vi cu hi n gin ................................40

Hnh 4.6. V d hi p i vi loi cu hi NORMAL ...............................................42

Hnh 4.7. nh x Ontology tng tc vi ngi dng i vi loi cu hi

UNKN_REL........................................................................................................................43

Hnh 4.8. V d hi p i vi loi cu hi UNKN_TERM .......................................44

Hnh 4.9. V d hi p i vi loi cu hi UNKN_TERM .......................................45

Hnh 4.10. V d hi p i vi loi cu hi AFFIRM_NEG ........................................46

Hnh 4.11. Tng quan nh x Ontology vi loi cu hi THREETERM ...................47

Hnh 4.12. V d hi p i vi cu hi v s lng.......................................................51

Hnh 4.13. Trch chn cu tr li i vi loi cu hi NORMAL, UNKN_REL ..52

Hnh 4.14. V d hi p i vi loi cu hi NORMAL, UNKN_REL ................53

Hnh 4.15. Thnh phn trch chn cu tr li i vi loi cu hi UNKN_TERM ...54

Hnh 4.16. V d hi p i vi loi cu hi UNKN_TERM .....................................55

Hnh 4.17. V d hi p i vi loi cu hi UNKN_TERM .....................................55

Hnh 4.18. Thnh phn trch chn cu tr li i vi loi cu hi AFFIRM_NEG ..56


viii

Hnh 4.19. V d hi p i vi loi cu hi AFFIRM_NEG ....................................56

Hnh 4.20. Thnh phn trch chn cu tr li i vi loi cu hi THREETERM ....57

Hnh 4.21. V d hi p i vi loi cu hi THREETERM ......................................58


ix

Danh sch bng

Bng 5.1. nh gi h thng i vi cc cu hi tr li c .........................................59

Bng 5.2. nh gi h thng i vi cc cu hi li .........................................................60

Chng 1. Gii thiu Nguyn Quc i

1

Chng 1.

Gii thiu

Trong tm kim thng tin, hi p (Question Answering QA) l nhim v t

ng tr li cu hi di dng ngn ng t nhin. Cc cu hi trong mt min ng

dng c th c th c tr li thng qua cc k thut x l ngn ng t nhin. Nhng

cc h thng gp phi vn : lm th no m t c tri thc trong min ng dng.

Cc nghin cu hin nay tp trung vo s dng Ontology lm c s tri thc, do

Ontology c kh nng m t mt tp cc khi nim trong min c th v cc mi quan

h gia cc khi nim. Hin nay, nhu cu tm kim thng tin ting Vit di dng hi

p l rt ln nhng cc h thng hi p cho ting Vit cn cha c nhiu nghin cu

ng dng c th.

Trong kha lun ny, chng ti xut Phng php xy dng h thng hi

p ting Vit da trn Ontology. Phng php ca chng ti c th p dng cho

nhiu min tri thc. Da vo phng php ca mnh, chng ti xy dng mt h thng

th nghim trn min tri thc trng i hc, m c th l min tri thc v i hc

Cng Ngh. Chng ti thit k mt Ontology th nghim cho min tri thc ny. Cc

cu hi lin quan n min ny sau khi phn tch [1], c nh x vo trong

Ontology thit k. Ri t , chng ti hnh thnh nn cc b m t tng ng vi

Ontology. Tip n, chng ti trch chn ra cu tr li ng ngha tt nht c th cho

cu hi ca ngi dng. Nhng kt lun v nh gi v h thng hi p ting Vit

cho thy h thng hot ng tt vi cc cu hi c hi.

Phn cn li ca kha lun c chia thnh:

Chng 2: Chng ti gii thiu tng quan v h t hng hi p da trn

Ontology, v nhng khi nim lin quan. Ngoi ra, chng ti a ra mt vi tm hiu

i vi cc h thng hi p hin nay.

Chng 1. Gii thiu Nguyn Quc i

2

Chng 3: Chng ti gii thiu cc khi nim c bn v Ontology, ngn ng

Web Ontology (Web Ontology Language OWL). ng thi, chng ti cng gii

thiu v Sesame, c s dng lu tr cc Ontology OWL cho min ng dng c

th.

Chng 4: Chng ti a ra kin trc ca h thng, cc thnh phn x l cho h

thng. Tip n, chng ti gii thiu cch thit k mt Ontology OWL cho mt min

tri thc trng i hc Cng Ngh. Da vo Ontology ny, chng ti m t chi tit

trch rt cu tr li ng ngha tt nht c th cho mt cu hi.

Chng 5: Chng ti a ra nhng nh gi thc nghim ca h thng.

Chng 6: Kt lun li ni dung kha lun, v nhng kt qu m h thng hi

p ting Vit da trn Ontology t c.

Chng 3. Ontology Sesame Nguyn Quc i

3

Chng 2.

Tng quan v hi p

2.1 Tng quan v h thng hi p da trn Ontology


ng tr li cu hi di dng ngn ng t nhin. tm cu tr li cho mt cu hi,

mt chng trnh my tnh c th s dng mt c s d liu tin cu trc hoc s dng

mt tp cc vn bn ngn ng t nhin.

Trong khoa hc my tnh, Ontology l biu din hnh thc ca mt tp cc khi

nim trong min c th v cc mi quan h gia cc khi nim. Ontology c dng

suy lun cc thuc tnh trong min, c th c dng nh ngha min [56].

a s cc phng php ph bin trong vic xc nh thng tin cn thit l s

dng cng c tm kim. Vi cu hi u vo, cc cng c ny a ra cu tr li n

gin vi vic so khp cc t kha. X l ngn ng t nhin (Natural Language

Processing NLP) c s dng nhn ra cu trc c php v ng ngha ca cu

hi, v cc ti liu thch hp cha ng cc cu tr li cho cu hi s c tr li. y

l i vi cc cu hi n gin, nhng cc cng c ny s kh c th thc hin c

vi cc cu hi phc tp gm cc cu hi how, why hoc what .

Vn chnh y l cc ng dng hi p duy tr vic hon thin cng c tm

kim da vo t kha cho n khi i hi NLP hiu cu trc ng ngha cng nh cu

trc c php ca cu hi. Vic biu din r rng cc ng ngha ca d liu trong min

ng dng c th to kh nng cung cp mt dch v mc mi.

Phn tch v nghin cu nhng suy lun trong Ontology cho h thng hi p to

kh nng m t ng ngha cho min ng dng. Trong Ontology, cc thut ng cng

vi quan h c nh ngha r rng trong min c th cho php chia s v s dng

li tri thc. Vi u im c a ra, Ontology c s dng miu t mt min


4

ng dng c th. Cc khi nim v cc mi quan h c nh ngha trong min cng

vi ngha ca chng c s dng mt cch nht qun trong min c th .

Hnh 2.1. Tng quan v h thng hi p da trn Ontologies [2]

Da vo kin trc trong hnh 2.1, Ontology xc nh cc khi nim c lin quan,

bng phng php tip cn lai, hoc kt hp cc phng php c php v cc phng

php thng k c s dng trch ra cc khi nim t cc ti liu.

Phng php da vo c php pht hin mu cc danh t ghp v min cu trc

c th. Pht hin mu ph hp vi cc phng php trch chn khi nim khc. Cc

cch tip cn thng k cho vic trch chn khi nim thng nhn bit s xut hin ca

cc t vng trong mt hoc nhiu tp cc ti liu xc nh. Mt khi nim xut hin

nhiu trong mt ti liu, th khi nim ny c ngha v c trch chn.

Gn nhn t loi c dng ci tin vic nhn dng cc khi nim. Cc t

c gn nhn lun da vo u tin c trch chn. Cc t loi khc chng hn

nh gii t lin kt, gii t nhn dng s b loi tr v chng khng mang thng tin v

min khi nim. Cc khi nim c hnh thc ha s thch hp d dng cu trc


5

nn Ontology. Tuy nhin, cc khi nim c tch ring l v ngha do khng th

truyn t ni dung quan trng. Do , vic trch chn quan h gia cc khi nim

di dng quan h ch th -quan h - i tng.

Mi quan h ng ngha c th c nhn bit vi s h tr ca WordNet.

WordNet l mt c s d liu t vng trc tuyn cng vi mt tp cc ngha. Wordnet

c s dng tm kim quan h (lin kt is-a v part-of) gia cc khi nim i vi

cc t ng m, cc t ng ngha gim s d tha v nhn. Quan h thng biu

din di dng cc ng t, v c th c trch ra bi so khp ng t v cc khi

nim trong cu.


6

2.2 Khi nim v hi p (Question Answering QA)

2.2.1 Khi nim hi p


ng tr li cu hi di dng ngn ng t nhin. tm cu tr li cho mt cu hi,

mt chng trnh my tnh c th s dng mt c s d liu tin cu trc hoc s dng

mt tp cc vn bn ngn ng t nhin.

Nghin cu QA nhm mc ch x l cc loi cu hi: s kin, danh sch, nh

ngha, cc cu hi nh th no, ti sao, cc cu hi mang tnh gi thuyt, cc cu hi

hn ch v ng ngha v cu hi s dng a ngn ng. C hai khi nim trong hi p

l hi p min ng v hi p min m.

Hi p min ng (closed-domain) x l cc cu hi trong mt min c th, v

c th xem nh mt nhim v n gin v cc h thng x l ngn ng t nhin

(Natural Language Processing NLP) c kh nng khai thc tri thc min c th c

biu din bi Ontologies.

Hi p min m (open-domain) x l cc cu hi c ni dung v mi th v ch

c th da trn cc Ontology tng qut v tri thc tng hp t khp ni trn th gii.

Ni cch khc, cc h thng ny thng lu tr mt lng ln d diu c sn t

trch chn ra p n cho cu hi tm kim.

Hi p (Question Answering QA) cn s dng nhiu phng php NLP phc

tp hn cc tm kim thng tin phc hi ti liu. Do , cc cng c tm kim ngn

ng t nhin c nh gi vt xa cc cng c tm kim hin nay.

Trong mc 2.3, chng ti a ra tng quan mt s h thng hi p c phn

loi da trn min ng v min m.

2.2.2 Kin trc hi p

H thng QA u tin pht trin vo nhng nm 1960 [64]. Cc h thng ny v

c bn l cc giao din ngn ng t nhin i vi cc h chuyn gia - nhng h thng

c xy dng ring cho tng min ng dng c th. Nguc li, cc h thng QA

ngy nay li s dng cc ti liu vn bn lm ngun tri thc c bn v kt hp vi

http://en.wikipedia.org/wiki/Natural_language_processing


7

nhiu k thut NLP khc nhau tm ra cc cu tr li. Cc h thng QA hin nay

thng bao gm mt module phn loi cu hi, gip xc nh loi cu hi v loi cu

tr li tng ng. Sau khi phn tch cu hi, h thng s s dng mt s module p

dng cc k thut NLP phc tp ln mt lng vn bn c gim bt nh module

phn tch cu hi. Tip theo, mt module phc hi ti liu s dng cc cng c tm

kim, module ny dng nhn dng ti liu hoc on vn bn trong tp ti liu c

kh nng cha cu tr li trong . Sau , mt b lc s chn sn mt on vn bn

ngn c cha chui k t cng kiu vi cu tr li c ch i. V d, nu cu hi l:

Who invented Penicillin?

B lc tr li vn bn c cha tn ngi. Cui cng, mt module trch chn cu

tr li tm kim thm cc lin kt trong vn bn quyt nh xem trong s cc p n

uc lc ra th u l p n thc s.

2.2.3 Cc phng php hi p

Hi p (Question Answering QA) ph thuc rt nhiu vo tp ti liu tm kim

c tt hay khng. Nu h thng khng tm ra c cc ti liu c cha cu tr li th

gn nh khng c h thng QA no thc hin c. V vy, quy m tp ti liu cng

ln th cng c ch cho qu trnh tr li cu hi, tr trng hp lnh vc m cu hi

cp n khc hon ton so vi ti liu sn c.

Trong cc tp d liu ln, khi nim v d tha d liu l s lng ln thng tin

c kh nng c din t theo nhiu cch khc nhau trong cc ti liu v ng cnh

khc nhau. iu ny dn n 2 li ch sau:

(1) Thng tin thch hp xut hin dui nhiu hnh thc khc nhau s gip h

thng QA thc hin cc k thut NLP phc tp mt cch d dng hn.

(2) Cc cu tr li ng c th c lc ra bi cu tr li thch hp s xut hin

nhiu ln hn trong cc ti liu so vi cc trng hp tr li khng chnh xc.

Phn tch b ni : Mt vi phng php tr li cu hi s dng cc k thut da

vo t kha xc nh v tr ca cc on vn bn hay cu ng ch trong cc ti

liu uc tm kim. Sau , h thng tm kim da trn s c mt ca p n cn tm

ang nm trong nhng on vn bn hay cu . Vic sp xp cc p n c thc

hin ngay sau da vo cc c im c php ca cu hay on vn bn, chng hn


8

da vo trt t t, v tr ca cu hay on, v nhng im tng ng khc ca cc cu

hay on ny so vi cu hi tm kim.

Khi s dng nhng tp d liu ln vi s d tha d liu tt, nhiu h thng

dng cc mu tm ra p n cui. Nu t ra cu hi:

What is a cat?

H thng s tm ra chui con What is a X? v ri thc hin qu trnh tm kim

cc ti liu bt u vi X is a Y. Phng php ny thng lm vic tt i vi cc

cu hi n gin nhm tm kim cc thng tin thc t nh tn, ngy thng, a im v

s lung.

Phn tch chiu su: Nhng trng hp phng php da vo t kha khng

p ng c , th h thng dng cc x l phc tp nh phn tch c php, phn tch

ng ngha v ng cnh ca cu hi. Da vo , h thng tch ra hoc cu to nn cu

tr li. Nhng k thut ny c th bao gm k thut nhn dng thc th c tn, phng

php nhn bit mi quan h, phn tch t ng ngha, cc k thut bin i c php,

phng php loi b nhp nhng v ngha ca t, phng php bin i hnh thi

logic, Nhng h thng ny cng s dng tri thc trong cc Ontology suy lun

thng qua cc khi nim v cc lin kt ng ngha.

Nhiu dng cu hi kh nh dng cu hi why, how, cc cu hi gi nh, cu hi

gii hn v khng gian v thi gian, cc cu hi hi thoi, cc cu hi nhp nhng cn

tt c nhng phng php phn tch chiu su nh trn h thng nhn bit cu hi.

Tng t nh vy, nhng on vn bn phc tp hoc nhp nhng cng cn c p

dng nhiu phng php NLP nhn ra c ni dung vn bn.

Hi p (QA) thng k gii thiu cc module x l cu hi da vo thng k v

trch chn ra cu tr li. Nhiu cng c NLP nh k thut nhn dng thc th c tn,

phn tch c php, gn nhn t loi, nhn dng ranh gii cu v phc hi ti liu c th

s dng nh l cc ng dng thng k.

Mc di y, chng ti tm hiu mt s h thng hi p da vo phn loi

min ng, min m, gii thiu vi h thng hi p c s dng Ontology. Chng ti

m t qua mt s u nhc im ca cc h thng , ng thi cng gii thiu qua

cc phng php m cc h thng ny s dng tm kim cu tr li cho cu hi.


9

2.3 Giao din ngn ng t nhin min ng

Giao din ngn t nhin (Natural Language Interface) min ng l cc h thng

hi p da trn c s d liu. Cc cu hi c t ra di dng ngn ng t nhin,

t truy vn vo c s d liu. Phn ln cc h thng NLIDB (Natural Language

Interface to Database) u tin c to ra vi mt c s d liu c bit. Do vy, cc

thng hi p ny khng th sa i d dng s dng km vi cc c s d liu

khc, v cng kh p dng i vi cc min ng dng khc. Mt vi h thng NLIDB

s dng k thut so khp mu, Androutsopoulos [6] a ra v d cu hi c cha t

capital theo sau tn nc, th h thng ny a ra tn th tng ng vi tn nc

, v t tm cu tr li cho cu hi:

what is the capital of Italy?,

print the capital of Italy, hoc

Could you please tell me the capital of Italy.

Cc phng php thng s dng trong cc h thng khc thng da vo tnh

tng ng v ng ngha hoc da vo thng k. V d, FAQ Finder [12] l mt h

thng tr li cu hi ngn ng t nhin, trong n s s dng cc file c sn ca

FAQ lm c s tri thc (Knowledge Base KB). H thng ny cng s dng

WordNet nng cao kh nng tm kim cu tr li thch hp cho cc cu hi c

a ra. FAQ Finder [12] s dng hai phng php o: s tng ng v ng ngha v

s tng ng da vo thng k. Tuy nhin, phng php thng k c v khng hu

ch v phng php ny thung ch c ch i vi cc ti liu di vi lng d liu ln,

c cc t cho so snh thng k [12]. Cn phng php o tng ng v ng ngha

li da vo cc mi lin h gia cu hi ca ngi dng v cu tr li. Mi quan h

ng ngha c th c nhn bit vi s h tr ca WordNet. WordNet l mt c s d

liu t vng trc tuyn cng vi mt tp cc ngha. Wordnet c s dng tm

kim quan h (lin kt is-a v part-of) gia cc khi nim i vi cc t ng m, cc

t ng ngha. Vn chnh trong phng php o tng ng v ng ngha khng

th x l c cc t vn khng c trong KB.

Cc th h NLIDB tip theo s dng ngn ng biu din trung gian. Ngn ng

ny phn nh c ngha ca cu hi ngi dng da theo ngn ng bc cao v c

lp vi cu trc c s d liu [6]. Chng hn, h thng ngn ng t nhin i vi c


10

s d liu da trn ng ngha hc hnh thc [19], to ra phn bit r rng gia thao

tc u v thao tc cui trong qu trnh x l ngn ng t nhin (Natural Language

NL). Thao tc u cung cp mt nh x gia cc cu ting Anh ti cc biu thc ng

ngha hc, v thao tc cui nh x cc biu thc ny vo trong cc biu thc ngha

i vi min cu hi. TEAM [41] l mt h thng NLIDB th nghim, linh hot c

pht trin vo nhng nm 1980. H thng hi p TEAM, bao gm hai thnh phn

chnh: (1) thnh phn nh x cc biu thc NL thnh cc biu din hnh thc, (2) thnh

phn chuyn i nhng biu din ny thnh cc cu lnh i vi c s d liu. TEAM

[41] to ra s phn tch gia qu trnh ngn ng v qu trnh nh x ln KB.

PRECISE [47] l chng trnh nh x cc cu hi ti truy vn SQL tng ng

bi vic nhn dng cc lp cu hi n gin. Cc cu hi l mt tp cc cp thuc tnh

gi tr v cng vi mt quan h. Mi thuc tnh trong c s d liu c lin kt vi

mt wh-value (what, when, where,). Trong chng trnh PRECISE, mt b t vng

c s dng tm cc t ng ngha. Tuy nhin, trong chng trnh PRECISE, vic

tm mt nh x da theo t vng cho c s d liu i hi mi t vng phi ring bit

vi nhau. H thng ny khng th phn tch c ng ngha cc cu hi c cha cc t

m h thng cha bit, v th chng trnh khng th x l c cu hi ny. Ni cch

khc, chng trnh PRECISE s khng tr li cc cu hi m cha nhng t khng c

sn trong t in ca n.

2.4 Cc h thng QA min m

Cc ng dng QA dnh cho vn bn thng gm 2 bc, c trch dn bi

Hirschman [26]: (1) Nhn dng cc kiu ng ngha ca i tng c tm kim bi

cu hi, (2) Xc nh cc rng buc b sung cho i tng tr li. Cc rng c th l

cc t kha (s lng t kha c th c khuch i do vic s dng cc t ng

ngha hoc cc bin th hnh thi) dng so khp i vi cc cu tr li. Cc rng

buc cng c th l cc mi quan h c php hoc ng ngha gia mt i tng tr

li v cc i tng khc trong cu hi. Do vy, nhiu h thng khc hnh thnh

phn cp loi cu hi da vo dng cu tr li tm kim.

Trong chng trnh LASSO [45], phn cp loi cu hi c hnh thnh t vic

phn tch d liu hun luyn TREC-8 (Text Retrieval Conference 8). Khi nhn c


11

mt cu hi, LASSO t ng tm kim: (a) loi cu hi (what, why, who, how, where),

(b) loi cu tr li (person, location), (c) trng tm cu hi, l thng tin chnh c

yu cu bi cu hi. Ngoi ra, phn cp loi cu hi cn gip nhn dng t kha trong

cu hi. i khi, nhiu t c trong cu hi s khng xut hin li trong cu tr li. Cc

h thng min m c gng tm kim cc t ng ngha, cng vi cc bin th hnh thi

ca t ng ngha cho cc thut ng hoc cc t kha.

Trong TREC-9 [18], h thng FALCON c m t bi Harabagiu et al. [25] cho

cu tr li ng ngha c nh x bi cng c nhn dng thc th c tn. Nu khi

nim trong cu hi cho bit loi cu tr li, h thng FALCON s c nh x cu hi

vo trong phn loi cu tr li. Tt c cc danh t (v cc bin i hnh thi t vng)

c lin quan ti cc khi nim xc nh loi cu tr li th u c nhn bit thng

qua cc t kha. FALCON a ra cu tr li c lu tr nu c mt cu hi tng t

c hi trc .

START [33] ch trng vo cc cu hi v a l v thng tin phng th nghim

ca MIT. START s dng gi b ba l i tng thuc tnh gi tr. y l mt

h thng ln c nh gi cao trong cc h thng hi p (Question Ansering QA)

bi kh nng phn tch v tng hp cu hi. Vi mt cu hi dng phc tp, START

c c ch chia cu hi ny ra thnh nhng cu hi nh, mi cu hi nh s tm c

cu tr li trc tip trong c s d liu. Sau START tng hp kt qu t nhng cu

tr li ca cc cu hi nh . Ngoi ra START cn c bit hu dng trong vic tm

ra cu tr li bi kh nng phn tch ng ngha rt tt ca n.

Litkowski [38] a ra h thng DIMAP, h thng ny trch chn cc b ba quan

h ng ngha sau khi ti liu c phn tch c php v cy c php c kim tra.

Cc b ba trong DIMAP s c lu li trong mt c s d liu vi mc ch dng

tr li cc cu hi. B ba quan h ng ngha c cp trn bao gm cc i tng

(SUBJ, OBJ, TIME, NUM, ADJMOD), c mt quan h ng ngha m t li vai tr ca

i tng, v mt t trong cu c lin quan ti i tng ny. Mt b ba thng tng

ng vi mt hnh thi logic. Cc i tng l thnh phn ch cht ca cc b ba

trong DIMAP, cc thnh phn quan trng (cc danh t chnh, ng t chnh v bt c

tnh t hoc danh t b ngha no) uc xc nh cho mi loi cu hi. H thng phn

cc cu hi ra lm su loi cu hi: thi gian, a im, ai, ci g, kch c v s lng.


12

PiQASso [8] s dng mt php phn loi cu hi phn loi cc cu hi v:

ngi, t chc, thi gian, s lng v v tr (l cc loi c bn). Ngoi ra, PiQASso

cn c thm 23 loi danh t trong WordNet. Loi cu tr li c th c kt hp vi

cc loi danh t ny. V d, trong cu hi c cha who, where th loi cu tr li

s l v person hoc organization. Cc loi cu hi c th c xc nh trc tip

t cc t hi: who, when, where. C nhiu trng hp cn thm cc thng tin

b sung khc. V d, vi cc cu hi how th loi cu hi c tm thy t tnh t

theo sau t how (how many hoc how much) ch s lung, hoc how long,

how old ch thi gian, v.v Loi cu hi what (noun) thng l ng ngha ca

danh t c xc nh bi WNSense. WNSense l mt cng c dng cho vic phn

loi ngha ca t. Cc cu hi thuc dng what (verb) c cng loi cu tr li vi i

tng ca ng t. Cc cu hi what is cng da vo vic xc nh ng ngha ca t

hi. Tuy nhin, PiQASso nhn nh khng phi lc no cng c th ch cn tm ra

ng ngha ca t, bi v tnh trng thiu ng cnh khng cho php xc nh ngha

chnh xc ca t. V vy, mi i tng cng c th c chp nhn nh l cc cu tr

li cho cc cu hi mang tnh nh ngha, min l chng xut hin nh l mt ch th

trong mt cu dng is-a. Nu xc nh c loi cu tr li cho mt cu hi th n s

c chuyn qua b lc so khp quan h trong qu trnh phn tch.

2.5 Ontologies trong QA

Nhiu h thng n gin dng mt Ontology nh mt c ch h tr cho vic m

rng cu hi tm kim trong qu trnh tm kim thng tin. Basili et al. [9] c cp n

tnh kh thi ca vic xy dng mt h trng QA da vo Ontology trong ng cnh ca

mt web ng ngha. Cc tc gi nghin cu phng php ny trn ng cnh mt d

n mang tn MOSES, vi mc tiu pht trin mt phung php lun da vo Ontology

tm kim, t chc, bo tr v thch hp vi nhng ni dung Web c cu trc v ng

ngha. Basili et al. [9] nghin cu xem phng php da trn Ontology ny c th h

tr cho hi p khng v nu c th bng cch no. Basili et al. [9] cng a ra mt

cch phn loi cc cu hi, t h thng c tr gip v xem xt ni dung cu hi

mc ln i vi cc khi nim v cc mi quan h suy ra t Ontology.

Phng php da vo tri thc [14] b sung cc vn bn trc tuyn vi mt thnh

phn QA da vo tri thc. H thng suy ra cu tr li tng ng vi nhng cu hi


13

ca ngi dng m nhng cu hi bn ngoi phm vi ca vn bn c ghi t

trc trong h thng. Tri thc c lu tr trong mt c s tri thc v c cu trc

nh l mt Ontology ca min. Ging nh nhiu h thng hi p, [14] cng c mt

tp nh gm cc loi cu hi chung bit lm th no tr li. Cc loi cu hi

c lin kt vi cc khi nim trong KB. Khi mt khi nin a ra, cc loi cu hi

thch hp hoc tng ng chnh l loi cu hi gn lin vi khi nim ca chnh cu

hi . Cc cu hi cung cp ng cnh h thng da vo tm ra p n cho cu

hi tm kim.

Cc h thng hi p (Question Answering QA) cho php ngi dng a ra

mt cu hi di dng ngn ng t nhin v nhn c cu tr li ngn gn, trong

nhiu trng hp cn c km theo ng cnh c th. AquaLog [3] l mt h thng QA

ngn ng t nhin da trn Ontology, v da vo tri thc c m ha trong

Ontology. H thng ny cng da vo chc nng ng ngha hc loi b nhp nhng

v ngha ca cc cu hi v a ra cc cu tr li. AquaLog s dng biu din trung

gian trong sut qu trnh x l, t vic biu din cu hi ngi dng n vic biu

din thnh mt b m t tng ng vi Ontology. Trong AquaLog, s nhp nhng ca

NL c tnh n, v th, nu giai on phn tch cu hi khng c kh nng loi b

tnh nhp nhng ny th n vn s xut hin trong giai on tip theo . AquaLog c kh

nng lp lun v cu trc Ontology to ngha c ho cc lp hoc cc mi quan h.

AquaLog phn loi cu hi cn c trn loi b ba l biu din ng ngha ca cu hi.

Trong khi , hu ht cc h thng QA min m li phn loi cc cu hi theo mc

tiu tr li. Aqualog tm kim cc mi quan h gia cc thut ng, hoc gia mt thut

ng vi gi tr ca n. AquaLog dng mt b ba cho mt mi quan h gia cc thut

ng, cho d mi quan h ny khng r rng.

Chng ti tin tng vo cc u im chnh ca mt h thng hi p da trn

Ontology trong Web ng ngha. Khi so snh cc loi h thng hi p khc nhau,

h thng hi p da trn Ontology c th s dng min tri thc c cung cp bi

Ontology x l cc t khng c tm thy trong c s tri thc v loi b nhp

nhng v ngha ca t. Do vy, chng ti a ra h thng hi p cho ting Vit da

trn Ontology (chng 4). Trong chng 3, chng ti gii thiu cc khi nim lin

quan ti Ontology, cc khi nim v Sesame, cu hnh Sesame server lu tr

Ontology cho h thng ca chng ti.


14

Chng 3.

Ontology Sesame

Chng ti s a ra cc khi nim c bn lin quan ti Ontology (mc 3.1), ngn ng

Web Ontology (mc 3.2). Sau , chng ti gii thiu cc khi nim lin quan ti

Sesam, cu hnh Sesame server lu tr cc Ontology cho h thng (mc 3.3).

3.1 Khi nim v Ontology

3.1.1 Khi nim

Trong khoa hc my tnh, Ontology l biu din hnh thc ca mt tp cc khi

nim trong min c th v cc mi quan h gia cc khi nim. Ontology c dng

suy lun v cc thuc tnh ca min, c th c dng nh ngha min [56].

Theo l thuyt, Ontology l mt c t hnh thc, r rng ca mt khi nim

c dng chung [56]. Mt Ontology cung cp mt bng t vng dng chung, bng t

vng ny c th c s dng m hnh ha mt min, cung cp cc i tng v

(hoc) cc khi nim ang c, v cc thuc tnh cng vi cc mi quan h ca chng.

Ontologies c s dng trong tr tu nhn to, Web ng ngha, cng ngh phn

mm, trong tin sinh, th vin hc, v kin trc thng tin nh mt dng biu din tri

thc v th gii hoc mt v mt min ng dng c th.

3.1.2 Tng quan v Ontology

Ontology l m hnh m t tri thc v min ng dng c th, biu din cc i

tng, cc khi nim, cng vi cc thuc tnh v cc mi quan h.


15

3.1.2.1 Cc thnh phn ca Ontology

Ontologies hin nay c chung cc cu trc ging nhau v khng quan tm ti

ngn ng m chng c th hin. Hu ht cc Ontology miu t cc thc th (cc i

tng), cc lp (cc khi nim), cc thuc tnh v cc mi quan h.

Cc thnh phn ph bin ca cc Ontologies bao gm :

- Cc thc th: cc i tng (cc i tng c bn).

- Cc lp: cc khi nim v cc i tng, hoc cc loi vt cht.

- Cc thuc tnh: cc c tnh, c trng, cc c im hoc cc tham s m

cc i tng (v cc lp) c th c.

- Cc mi quan h: cc cch cc lp, cc thc th c th c lin kt ti

cc lp (hoc thc th) khc.

- Cc thut ng chc nng: cc cu trc phc tp c hnh thnh t cc

quan h bit, s dng thut ng thch hp trong mt pht biu.

- Cc gii hn: cc m t c pht biu phi chnh xc v hp l.

- Cc quy tc: cc pht biu di dng mnh if then (iu kin kt

qu) miu t suy lun logic.

- Cc tin : cc khng nh (bao gm cc quy tc) trong mt hnh thc

logic v ng thi bao gm ton b l thuyt m Ontology miu t trong

min ng dng ca n.

- Cc s kin: cc thay i ca cc thuc tnh hoc cc mi quan h.

Cc Ontology thng c m ha bi cc ngn ng Ontology.

3.1.2.2 Cc thc th

Cc thc th (cc i tng) l cc thnh phn c bn, mc c s ca mt

Ontology. Cc thc th trong mt Ontology bao gm cc i tng c th nh ngi,

ng vt, bn gh, xe t, cng nh cc i tng tru tng chng hn nh cc

s, cc t. Mt Ontology c th khng cn bt k thc th no, nhng mc ch ca

Ontology l a ra phng php phn loi cc thc th, ngay c khi nhng thc th

ny khng l thnh phn trong Ontology.


16

3.1.2.3 Cc lp

Cc lp c th c nh ngha nh l mt s m rng (extension) hoc nh mt

tng cng (intension) [58]. Theo nh nh ngha m rng, cc lp l cc nhm,

cc b hoc cc tp hp cc i tng tru tng. Theo nh ngha tng cng, cc

lp l cc i tng tru tng c nh ngha bi cc dng gi tr, cc dng gi tr

ny l cc rng buc cho phn t ca lp. Trong nh ngha m rng cho thy mt lp

l mt tp cc lp con. Cn nh ngha theo tng cng, gia cc tp hp v cc lp

c nhiu khc nhau c bn. Cc lp c th phn loi cc thc th, phn loi cc lp

khc, hoc kt hp c hai phn loi. V d v lp:

- Ngi, lp ton b con ngi, hoc i tng tru tng c th c m

t bi cc tiu chun cho mt ngi.

Mt lp l m rng khi v ch khi lp c m t bi mi phn t ca lp.

Nu mt lp khng tha mn iu kin ny, khi y n l tng cng. Cc lp m

rng hot ng tt hn v x l tnh ton tt hn, v cng t nhp nhng, th li khng

cho php phn bit r rng gia cc lp. Trong khi , cc lp c nh ngha cng

thng c cc iu kin cn lin kt vi cc phn t trong mi lp. Mt vi lp

cng c th c cc iu kin , v trong cc trng hp ny s kt hp cc iu kin

cn v lm cho lp c nh ngha y .

Mt lp c th l lp con (hoc kiu con) ca mt lp no (lp cha) , v to ra

mt h phn cp cc lp. Lp con c tha k thuc tnh t lp cha. V vy, bt c

iu g ng i vi lp cha th cng ng vi tt c cc lp con ca n.

Hnh 3.1. V d v lp trong Ontology [58]

http://en.wikipedia.org/wiki/File:OntologyBasic.png


17

Mt phn vng l mt tp cc lp c lin quan cng vi cc quy tc c lin

kt. Cc quy tc c lin kt cho php cc phn chia cc i tng bi cc lp con

thch hp. Chng hn, hnh 3.1 hin th mt phn ca mt Ontology c mt phn vng

ca lp Car vi cc lp con 2-Wheel Drive Car v 4-Wheel Drive Car. Cc quy

tc phn vng xc nh nu c mt Car c th th c phn loi bi lp 2-Wheel

Drive Car hoc bi lp 4-Wheel Drive Car.

Cc quy tc phn vng bo m rng mt Car c th khng th c tn ti trong

c hai lp, khi y, phn vng c gi l mt phn vng ri. Nu quy tc phn

vng m bo mi i tng c th trong lp cha l mt i tng thuc t nht mt

trong cc lp con, th phn vng c gi l mt phn vng y .

3.1.2.4 Thuc tnh

Cc i tng trong Ontology c th c m t bi lin kt ca chng vi

nhng i tng khc, nhng lin kt ny thng c gi l cc thuc tnh, mc d

c th l nhng lin kt c lp. Loi i tng v loi thuc tnh xc nh loi quan

h gia chng. Mt i tng da vo thuc tnh lin kt ti i tng khc. V d:

i tng Nguyn_Quc_i c cc thuc tnh chng hn nh:

- Nguyn_Quc_i

- H_Ni

- k50_khoa_hc_my_tnh

Gi tr ca mt thuc tnh c th c mt kiu d liu phc tp.

3.1.2.5 Cc mi quan h

Cc mi quan h gia cc i tng trong Ontology ch ra cc i tng c

lin quan nh th no n nhng i tng khc. V quan h gia cc lp c th dn

n quan h gia cc i tng trong cc lp .

Cc quan h trong Ontology xut pht t kh nng mun miu t cc lin kt gia

cc khi nim. Tp hp cc loi quan h c s dng th hin ngn ng biu din

Ontology.

Loi quan h quan trng nht l quan h is-a-superclass-of, quan h ny l nghch

o is-a-subtype-of. Cc quan h ny xc nh cc i tng c phn loi do cc lp

http://en.wikipedia.org/wiki/Superclass


18

trong Ontology . Vi th d trong hnh 3.2, lp Ford Explorer is-a-subclass-of 4-Wheel

Drive Car, 4-Wheel Drive Car is-a-subclass-of Car v Car is-a-superclass-of 4-Wheel

Drive Car.

Hnh 3.2. V d v lp t

Cc quan h is-a-subclass-of to ra mt cu trc dng cy miu t cc i tng

lin quan n mt i tng khc nh th no.

Quan h ph bin khc l quan h c part-of, m t cc i tng kt hp li

vi nhau nh th no hnh thnh cc i tng ghp. Th d, nu Ontology v lp

t (hnh 3.2) c m rng bao gm khi nim Steering Wheel, th c quan h dng

Steering Wheel is-by-definition-a-part-of-a Ford Explorer. Khi Ontology thm vo

cc quan h part-of th cu trc cy tr nn phc tp v gp nhiu kh khn bin

dch bng tay. Tng t quan h is-a-subclass-of v is-by-definition-a-part-of-a, cc

Ontology thng bao gm cc quan h b sung m t ng ngha cho min ng

dng c th. Chng hn nh cc quan h:

- Cc quan h gia cc lp.

- Cc quan h gia cc i tng.

- Cc quan h gia mt i tng v mt lp.

- Cc quan h gia mt i tng ring l v mt tp i tng.

- Cc mi quan h gia cc tp i tng.

Cc quan h trong mt min c th c dng lu tr cc kiu d liu c th

hoc tr li cc cu hi c bit.

http://en.wikipedia.org/wiki/Subclasshttp://en.wikipedia.org/wiki/Subclasshttp://en.wikipedia.org/wiki/File:OntologyBronco.png


19

3.2 Ngn ng Web Ontology (Web Ontology Language)

Ngn ng Web Ontology OWL (Web Ontology Language) l mt h ngn ng

biu din tri thc cho cc Ontology, v c xc nhn bi W3C (World Wide Web

Consortium). H cc ngn ng ny phn ln da trn hai ng ngha: ng ngha OWL

DL v OWL Lite. Trong khi OWL Full s dng mt m hnh ng ngha mi nhm

cung cp tnh tng thch vi RDF Schema. Cc Ontology OWL a s thng s dng

c php RDF/XML, v OWL l mt trong cc cng ngh nn tng h tr Web ng

ngha (Semantic Web).

Khung m t ti nguyn RDF (Resource Description Framework) l mt h

thng cc c im k thut ca W3C (World Wide Web Consortium) c thit k

c o nh mt m hnh siu d liu. RDF c dng m t khi nim hoc m

hnh ha thng tin [61].

RDF Schema (vit tt khc nh RDFS, RDF (S), RDF-S, hoc RDF/S) l mt

ngn ng biu din tri thc m rng, cung cp cc thnh phn c bn m t

Ontology. RDF Schema cn c gi l t vng RDF, dng cu trc cc ti nguyn

RDF [62].

3.2.1 OWL Ontology

Trong OWL Ontology, d liu c m t nh mt tp cc i tng v mt tp

cc thuc tnh lin kt cc i tng vi nhau. OWL Ontology c mt tp cc rng

buc gia cc lp v cc quan h gia cc lp . Cc rng buc ny cung cp ng

ngha cho Ontology, v c th cho php h thng tm cc thng tin b sung da vo d

liu bit.

V d, Ontology c rng buc thuc tnh hasMother ch c lin kt gia hai

i tng khi thuc tnh hasParent cng lin kt gia hai i tng . Cc i

tng ca lp HastypeOBlodd khng lin quan n cc i tng ca lp

HasTypeABBlood thng qua thuc tnh hasParent. Nu c pht biu Harriet lin

kt ti i tng Sue qua quan h hasMother v Harriet l mt i tng ca lp

HastypeOBlodd. T , c th c suy lun rng Sue khng l i tng ca lp

HasTypeABBlood.

http://en.wikipedia.org/wiki/World_Wide_Web_Consortiumhttp://en.wikipedia.org/wiki/World_Wide_Web_Consortiumhttp://en.wikipedia.org/wiki/World_Wide_Web_Consortiumhttp://en.wikipedia.org/wiki/World_Wide_Web_Consortium


20

3.2.2 Mi quan h logic m t (Description logics DLs)

Vic xy dng Ontology quy m ln thng c sai st trong cc nh ngha v

lp, thuc tnh. Chng hn, vi quan h is-a th c 18 cch s dng khc nhau. Do

vy, OWL x l sai st da vo logic m t. Logic m t (Description logics DLs)

l mt h thng cc quy tc, v Ontology s dng DLs xy dng ln ng ngha.

3.2.3 Cc dng OWL

W3C (World Wide Web Consortium) a ra nh ngha v ba dng khc nhau

ca OWL, vi cc mc m t khc nhau l OWL Lite, OWL DL v OWL Full.

OWL Lite h tr cho nhng ngi dng cn mt phn loi phn cp v cc rng

buc n gin. Chng hn, OWL Lite h tr cc rng buc v s lng th ch cho

php s lng c gi tr l 0 hoc 1. OWL Lite cung cp cc cng c h tr nhm

lm n gin cc quan h nhiu ngha. Tuy nhin trong thc tin, cc c trng

OWL Lite c kt hp hnh thnh nn cu trc c sn trong OWL DL.

OWL DL c thit k cung cp kh nng m t ti a nht, trong khi gi li

tnh y , tnh quyt nh v tnh sn dng ca nhng thut ton suy lun mang tnh

thc t. OWL DL bao gm tt c cc cu trc ngn ng OWL, nhng ch c th c

s dng trong cc gii hn bit.

OWL Full c hnh thnh da trn cc ng ngha khc nhau t OWL Lite v

OWL DL. OWL Full c thit k m bo tnh tng thch vi RDF Schema.

Trong OWL Full mt lp c th c x l ng thi nh mt tp cc i tng, iu

ny khng c cho php trong OWL DL. OWL Full cho php mt Ontology b sung

ngha ca cc t vng c nh ngha t trc. Nhng thit lp di y m t quan

h gia cc dng OWL, nhng iu ngc li khng ng:

- Mi Ontology OWL Lite hp l l mt Ontology OWL DL hp l .

- Mi Ontology OWL DL hp l l mt Ontology OWL Full hp l .

- Mi kt lun OWL Lite hp l l mt kt lun OWL DL hp l .

- Mi kt lun OWL DL hp l l mt kt lun OWL Full hp l.

http://en.wikipedia.org/wiki/World_Wide_Web_Consortium


21

3.3 Sesame

3.3.1 Khi nim v Sesame

Chng ti gii thiu trong phn 3.2, khung m t ti nguyn RDF (Resource

Description Framework) l mt h thng cc c im k thut ca W3C (World Wide

Web Consortium) c thit k c o nh mt m hnh siu d liu. RDF c

dng m t khi nim hoc m hnh ha thng tin.

RDF Schema (vit tt khc nh RDFS, RDF (S), RDF-S, RDF/S) l mt ngn

ng biu din tri thc m rng, cung cp cc thnh phn c bn m t Ontology.

RDF Schema cn c gi l t vng RDF, dng cu trc cc ti nguyn RDF.

Sesame l mt Java framework m ngun m lu tr, truy vn v suy lun i

vi RDF v RDF schema [59]. Sesame c th c s dng nh l mt c s d liu

cho RDF v RDF Schema, hoc l mt th vin Java cho cc ng dng cn tm kim

thng tin bn trong RDF.

Nu mt ng dng cn c mt file RDF ln, tm thng tin thch hp, v s dng

thng tin . Sesame cung cp nhng cng c cn thit phn tch, bin dch, truy

vn v lu tr tt c cc thng tin ny, nhng vo trong ng dng . Ngoi ra,

Sesame cung cp mt cng c cha ng cc tnh nng hu ch i vi RDF.

3.3.1.1 Sesame Server

Sesame c th c s dng nh l mt my ch vi cc ng dng khch c th

giao tip thng qua HTTP. Sesame c th c trin khai nh l mt ng dng Java

Servlet trong Apache Tomcat mt webserver h tr Java Servlets v ngn ng JSP.

Hnh 3.3. Sesame server [59]

http://en.wikipedia.org/wiki/World_Wide_Web_Consortiumhttp://en.wikipedia.org/wiki/World_Wide_Web_Consortiumhttp://en.wikipedia.org/wiki/World_Wide_Web_Consortium


22

3.3.1.2 Kho d liu v suy lun (Repositories and Inferencing)

Sesame framework c khi nim v kho d liu (repository). Mt kho d liu l

mt b lu tr cho RDF hoc l mt c s d liu quan h. Hu ht cc tng tc ca

Sesame u lin quan ti kho d liu, khi thm d liu RDF th b sung vo mt kho

d liu no , v thc hin truy vn i vi mt kho d liu c th.

Vi mt tp RDF v (hoc) RDF schema, Sesame h tr suy lun RDF Schema

(RDF Schema inferencing). Sesame c th tm thy thng tin n trong kho d liu do

d dng thm cc thng tin n vo kho d liu.

3.3.1.3 Tng quan kin trc Sesame

Hnh 3.4. Kin trc ca Sesame [59]

Tng lu tr v suy lun (the Storage And Inference Layer SAIL API) l giao

din chng trnh ng dng bn trong Sesame (internal Sesame API - Application

program interface) cung cp h tr suy lun (hnh 3.4). Cc x l ca SAIL cung cp

chc nng nh b nh m hoc x l truy cp ng thi. Mi kho d liu Sesame c

i tng SAIL ring biu din cho kho d liu .


23

Trong kin trc ca Sesame (hnh 3.4), pha trn SAIL, l cc module chc nng

ca Sesame, chng hn nh cc cng c truy vn SeRQL, RQL v RDQL, module

qun tr, v module trch xut file RDF. Truy cp vo cc module chc nng c sn

thng qua cc giao din chng trnh ng dng truy cp ca Sesame (Sesame's Access

APIs), bao gm hai phn ring bit: Repository API v Graph API. Repository API

cung cp quyn truy cp bc cao vo cc kho d liu Sesame, chng hn nh truy vn,

lu tr cc file RDF, trch xut file RDF, Graph API cung cp nhiu h tr b sung

cho x l RDF, chng hn nh cc cu lnh thm v loi b thc th, v to ra cc m

hnh RDF nh trc tip t code. Hai API ny b sung chc nng cho nhau, v thng

c s dng cng nhau trong cc ng dng.

Access APIs cung cp truy cp trc tip vo cc module chc nng ca Sesame,

hoc truy cp vo mt chng trnh khch (v d, mt ng dng vn phng s dng

th vin Sesame), hoc truy cp trc tip vo thnh phn tip theo l Sesame server.

Sesame server mt thnh phn cung cp cc truy cp da vo HTTP ti cc API ca

Sesame. Sau , trn pha my khch HTTP xa, tm Access APIs, s dng cho cc

giao tip vi Sesame.

3.3.2 Ci t Sesame

Sesame c th trin khai theo mt vi cch. Hai phng php ph bin nht bao

gm vic trin khai nh l mt th vin java, hoc trin khai nh l mt my ch.

3.3.2.1 Ci t th vin Sesame

Th vin Sesame gm tp cc file:

- Sesame.jar

- Rio.jar: Rio (RDF I/O) l mt tp cc b phn tch v b ghi cho cc nh

dng RDF (RDF/XML, Turtle, N-Triples).

- Openrdf-model.jar: Cc lp c s dng chung cho cc m hnh RDF.

- Openrdf-util.jar: Cc lp dch v c s dng chung.

Nhng lu tr (nm trong th mc lib/) cha cc lp Java c sn s dng

trong cc ng dng ring.

Sesame yu cu Java 2, phin bn 1.4 (hoc mi hn) hot ng ng.


24

Nu ci t Sesame s dng m hnh my khch my ch qua giao thc HTTP,

th cn thm cc th vin: Jakarta Commons File Upload, Jakarta Commons IO. Cc

th vin ny c th c tm thy trong th mc ext/ ca m ngun Sesame.

3.3.2.2 Ci t my ch Sesame

Phn mm c yu cu

My ch Sesame yu cu cc phn mm: Sesame, v Java servlet container

chy cc Sesame servlets.

Sesame s c th chy trn bt k Java servlet container h tr cc c im

k thut Servlet 2.2 v JSP 1.1, hoc mi hn. Sesame c th nghim vi

Tomcat, v trong Oracle, vi OC4J.

Sesame c mt s la chn lu tr d liu RDF, Sesame c th lu tr d liu

trong b nh, hoc c th lu tr d liu trn a trong mt cu trc file chuyn dng,

hoc n c th lu tr d liu trong mt c s d liu quan h.

Ci t Sesame trn Tomcat

Cc bc m t quy trnh ci t Sesame trn Tomcat:

- Ci t Tomcat theo mc nh.

- Ti th mc cc ng dng web ([TOMCAT_DIR]/webapps/) v to mt

th mc tn l sesame.

- Gii nn file sesame.war (c th tm c file ny trong th mc lib/) vo

trong th mc sesame va c to mi trong th mc cc ng dng web

ca Tomcat.

- Sao chp file [SESAME_DIR]/WEB-INF/system.conf.example thnh

[SESAME_DIR]/WEB-INF/system.conf.

- Khi ng li Tomcat server v Sesame s bt u hot ng. Truy cp

vo giao din web Sesame ti http://localhost:8080/sesame .

http://localhost:8080/sesame


25

3.3.2.3 Qun tr my ch

Thay i cu hnh h thng

Cu hnh ca Sesame c thit lp trong file [SESAME_DIR]/WEB-

INF/system.conf. thay i file cu hnh s dng cng c Configure Sesame! c sn

trong [SESAME_DIR]/WEB-INF/bin/. bt u thay i cu hnh, s dng

configSesame.bat (trn Windows) hoc configSesame.sh (trn UNIX) (hnh 3.5).

Np cu hnh h thng

Hnh 3.5. Cu hnh Sesame

Khi bt u Configure Sesame!, np file system.conf. Nu mun cu hnh

Sesame server ang chy, th c th np file trc tip t server ([File] [Load from

server...]), v nhp mt khu qun tr l admin.

Lu tr mt cu hnh h thng

Khi thay i cu hnh, cu hnh c th lu tr trn a ([File] [Save file as...]),

hoc c th gi trc tip ti Sesame server ang chy ( [File] [Send to server...]).


26

Thit lp mt khu qun tr

Nu cu hnh h thng khng thay i mt khu qun tr t trc, thit lp mt

khu, chn tab Server v thay th mt khu qun tr.

Thm v loi b ti khon ngi s dng

thm hoc loi b ti khon ngi dng, thc hin theo bc sau:

- M tab Users.

- Click vo biu tng Add user.

- loi b ti khon ngi dng th click vo nt Remove user.

Cu hnh cc kho d liu

Cu hnh cc kho d liu c sn, hoc thm mi, hoc loi b kho d liu bi

vic thit lp cu hnh s dng Configure Sesame! (hnh 3.5).

Chnh sa cu hnh mt kho d liu c sn

M tab Repositories v la chn kho d liu s thay i cu hnh, click nt

Repository details (hnh 3.6).

Hnh 3.6. Cu hnh kho d liu c sn trong Sesame


27

Trong ca s Repository (hnh 3.6) c th chnh sa mt s thng s ca kho d

liu. Phn pha trn ca s hin th ngn xp SAIL, phn pha di hin th cc thng

s SAIL c la chn trong ngn xp. Trong hu ht trng hp, cu hnh ch cn

chnh sa cc thng s pha di SAIL trong ngn xp.

Ca s thng tin chi tit Repository cng cho php cu hnh thay i cc quyn

truy cp ca ngi s dng i vi mt kho d liu. thay i quyn truy cp, s

dng tab Access rights, v chnh sa cc quyn ca ngi s dng hin hnh hoc

thm ngi dng mi.

Thm cc kho d liu mi

thm mt kho d liu mi th cu hnh ch cn sinh bn sao ca kho d liu c

sn. S dng nt Clone trn tab Repository thc hin vic ny. Vic ny to mt

bn sao ca cu hnh kho d liu hin thi c la chn, v sau c th chnh sa.

Loi b cc kho d liu

loi b mt kho d liu, la chn tab Repository, la chn mt kho d liu v

click vo nt Remove.

3.3.3 Giao din web ca Sesame

Sesame i km vi mt giao din Web cho php truy cp ti cc kho d liu

thng qua trnh duyt Web thng thng.

3.3.3.1 ng nhp

Trang u vo ca Sesame c t ti http://localhost:8080/sesame. Mn hin

th cung cp cho la chn cc kho d liu thao tc trn . ng nhp vo

Sesame, click lin kt log in v cung cp tn ngi dng v mt khu.Sau khi ng

nhp, la chn kho d liu mun thc hin cc x l.

Sau khi la chn kho d liu, mn hnh hin th giao din chc nng ca Sesame

(hnh 3.7).

http://localhost:8080/sesame


28

Hnh 3.7. Giao din web ca Sesame

Cc cng c trn nh ca mn hnh hin th thng tin ngi dng v thng tin

kho d liu, v cho php la chn cc thao tc khc nhau trn kho d liu ny. Cc

thao tc ny c phn loi trong cc thao tc c (chng hn nh cc truy vn) v

trong cc thao tc ghi (thm v loi b d liu).

3.3.3.2 Thm d liu vo mt kho d

Giao din web cung cp ba la chn thm d liu vo mt kho d liu

Sesame: Add file, Add (www) v Add (copy-paste).

Cc la chn Add file v Add (www) khng phc tp, la chn u tin cho

php la chn mt ti liu RDF trn a thm vo kho d liu Sesame, v la chn

th hai cho php thm cc ti liu RDF qua mt URL ti kho d liu.

Ty chn Add (copy-paste) cho php ti d liu ti Sesame bng cch g (hoc

sao chp v dn) trong vng vn bn. Vn bn c g l ti liu RDF/XML hp l.

Chng 4. H thng hi p ting Vit da trn Ontology Nguyn Quc i

29

Chng 4.

H thng hi p ting Vit da trn Ontology

Mc 4.1 chng ti gii thiu kin trc tng quan v h thng, cc thnh phn ca h

thng. Mc 4.2, chng ti gii thiu cch x l cu hi u vo ca h thng [1]. Mc

4.3, chng ti a ra cch thit k Ontology, v chng ti thit k mt Ontology th

nghim cho t chc, c th l trng i hc Cng Ngh. Mc 4.4 v 4.5, chng ti

m t h thng trch rt cu tr li bi thnh phn nh x Ontology v thnh phn trch

chn cu tr li. Cc cu hi c a ra trong min ng dng c th da trn

Ontology thit k trong mc 4.3, t chng ti a ra cu tr li ng ngha tt

nht c th ti ngi dng.

4.1 Kin trc tng quan ca h thng

Kin trc ca h thng (hnh 4.1) s gm hai thnh phn chnh, thnh phn x l

cu hi ngn ng t nhin, v thnh phn tm kim cu tr li. Trong kha lun ny,

chng ti s tp trung vo thnh phn tm kim cu tr li. Thnh phn x l cu hi

ngn ng t nhin m chng ti s dng c a ra bi Nguyn Quc t [1].

Hnh 4.1. Kin trc tng quan ca h thng hi p ting Vit da trn Ontology

Thnh phn x l

cu hi

ngn ng t nhin

B biu din

trung gian

Thnh phn

tm kim

cu tr li

Cu hi

ngn ng t nhin Cu tr li

ng ngha

Sesame server

ONTOLOGY OWL


30

Thnh phn tm kim cu tr li c chia lm hai thnh phn chnh l thnh

phn nh x Ontology v thnh phn trch chn cu tr li. Chng ti s gii thiu v

hai thnh phn ny i vi tng loi cu hi c th trong mc 4.4, 4.5. Chng ti s

dng thnh phn nh x Ontology to b m t tng ng vi Ontology, v dng

thnh phn trch chn cu tr li a ra cu tr li ng ngha nht c th ti ngi

dng.

Hnh 4.2. Kin trc ca thnh phn tm kim cu tr li

Hnh 4.2 m t kin trc ca thnh phn tm kim cu tr li. B biu din trung

gian cho cu hi sau khi c tin x l, l u vo cho nh x Ontology. nh x

Ontoloyg kt hp vi d liu t Ontology lu trn Sesame server, s dng thut ton

khong cch xu. Thut ton khong cch xu c s dng tm cc thut ng

tng ng thch hp trong Ontology v nh x Ontology cng c th tng tc vi

ngi dng c thut ng ph hp vi Ontology. nh x Ontology hnh thnh b m

t tng ng vi Ontology. V thnh phn trch chn cu tr li s dng b m t ny

a ra cu tr li ng ngha nht ti ngi s dng.

Thut ton

khong cch xu

B biu din

trung gian

Cu tr li

ng ngha Ngi

s dng

Tng tc

Sesame server ONTOLOGY OWL

Thnh phn tm kim cu tr li

Tin x l Pre-processing

Trch chn

cu tr li

nh x

Ontology

B ba m t tng

ng vi Ontology


31

Cu hi c x l bi thnh phn x l ngn ng t nhin c Nguyn Quc

t a ra [1], v hnh thnh nn b biu din trung gian. B biu din trung gian ny

m t thng tin cho cu hi u vo. Ty vo cu hi n gin hay phc tp m b

biu din trung gian c cho di dng quan h bc hai gia hai thut ng hoc quan

h bc ba gia ba thut ng. B biu din trung gian quan h bc hai c dng (thut

ng 1, quan h, thut ng 2). Trong , thut ng 1 v thut ng 2 l cc cm t

trong cu mang thng tin v i tng cng nh khi nim mun hi, v quan h l

cm t trong cu th hin quan h gia hai thut ng . Chng hn, vi cu hi:

Nguyn Quc i hc lp no? (lp, hc, Nguyn Quc i).

Trong trng hp ny b biu din trung gian gi l b ba biu din quan h bc

hai. Tng t nh vy, b biu din trung gian quan h bc ba c dng (thut ng 1,

quan h, thut ng 2, thut ng 3), cn c gi l b ba biu din quan h bc ba.

Ty thuc vo tng cu hi c th m b ba biu din cho cu hi c th thiu

thut ng 1 hoc quan h. V d:

hc sinh ca lp khoa hc my tnh ca trng i hc cng ngh l ai?

(?, hc sinh, lp khoa hc my tnh, trng i hc cng ngh).

nh x Ontology da vo b ba biu din cu hi ny hnh thnh nn cc b

m t cc khi nim, i tng v quan h tng ng vi Ontology. Cc b m t ny

cng c biu din di dng b ba quan h nh trn, nn chng ti gi l b ba m

t tng ng vi Ontology. Sau , thnh phn trch chn cu tr li s dng cc b ba

m t ny a ra cu tr li ng ngha tt nht ti ngi dng. Tng quan chi tit

v x l ca thnh phn nh x Ontology v trch chn cu tr li i vi cc cu hi

s c chng ti a ra trong 4.4 v 4.5.

Mc di y, chng ti gii thiu v thnh phn x l ngn ng t nhin [1].

Thnh phn x l ngn ng t nhin phn loi cu hi u vo hnh thnh nn cc

b ba biu din trung gian cho cu hi.


32

4.2 X l cu hi ngn ng t nhin

Thnh phn x l ngn ng t nhin [1], phn cc cu hi vo cc loi c th.

Phn loi cu hi cung cp nhng rng buc ng ngha cho cu tr li mong mun, v

cung cp thng tin nh x Ontology da vo hnh thnh nn cc b ba m t,

cng nh h thng to cu tr li ng ngha tt nht c th cho cu hi. Cc cu hi

c phn loi nh sau:

NORMAL: cu hi c b ba biu din trung gian l quan h bc hai gia hai khi

nim v c ba thnh phn. V d:

sinh vin no hc lp k50 khoa hc my tnh? (sinh vin, hc, lp k50 khoa

hc my tnh).

UNKN_TERM: cu hi c b ba biu din trung gian l quan h bc hai gia hai

khi nim, nhng thiu thut ng u. V d:

m sinh vin ca Nguyn Quc i l g? (?, m sinh vin, Nguyn Quc

i).

UNKN_REL: cu hi c b ba biu din trung gian l quan h bc hai nhng thiu

quan h gia hai thut ng. V d:

lp khoa hc my tnh c nhng sinh vin no? (lp khoa hc my tnh, ?,

sinh vin).

AFFIRM_NEG: y l cc cu hi dng ng sai. V d:

Nguyn Quc i c qu l H Ni phi khng? (Nguyn Quc t, c

qu, H Ni)

THREETERM: y l loi cu hi phc tp, cu hi c biu din b ba quan h

bc ba gia ba thut ng (thut ng 1, quan h, thut ng 2, thut ng 3). Ty vo

tng cu hi, b ba ny c th y thnh phn, hoc thiu quan h, hoc thiu

thut ng th nht.


33

V d:

sinh vin no hc lp khoa hc my tnh ca trng i hc cng ngh?

(sinh vin, hc, lp khoa hc my tnh, trng i hc cng ngh)

trng ca Nguyn Quc i ca Nguyn Quc t l g? (?, trng,

Nguyn Quc i, Nguyn quc t).

Trn y l cc loi cu hi m chng ti a ra hi h thng ny. Sau khi

chng ti thit k xong Ontology (phn 4.3), chng ti a ra tng quan v thnh phn

nh x Ontology v trch chn cu tr li (mc 4.4, 4.5) da trn cc loi cu hi nu

trn. T , chng ti nh gi h thng cho cc cu hi c hi.


34

4.3 Thit k Ontology bng Protege

Nh cp chng 3, trong khoa hc my tnh, Ontology lu tr thng tin

v min ng dng c th. Ontology l biu din hnh thc ca mt tp cc khi nim

v mt min c th v cc mi quan h gia cc khi nim. Trong Ontology, lp l tp

hp cc i tng, cc thuc tnh l cc c trng m cc i tng (v cc lp) c th

c, cn mi quan h l cch m cc lp, cc i tng th hin s lin kt ti cc lp

hoc cc i tng khc.

Hai quan h ph bin trong Ontology l is-a-superclass-of v is-a-subclass-of. V

d, trng is-a-superclass-of khoa, khoa is-a-subclass-of trng. Ngoi hai quan h

trn, Ontology c s dng th hin cc quan h trong min v phn loi cc quan

h, chng hn nh:

- Cc quan h gia cc lp.

- Cc quan h gia cc cc i tng.

- Cc quan h gia cc mt i tng v mt lp.

Do vy, vic thit k Ontology l cc k quan trng th hin tri thc v min

ng dng c th.

H thng hi p ting Vit da trn Ontology ca chng ti c th p dng i

vi nhiu min ng dng. Tuy nhin, trong kha lun ny, chng ti thit k mt

Ontology th nghim v mt t chc, c th l trng i hc Cng Ngh. T ,

da vo Ontology c thit k, chng ti s dng Sesame server lu tr v cn c

vo , chng ti s m t chi tit thnh phn nh x Ontology v trch chn cu tr li

(trong mc 4.4 v 4.5).

Chng ti thit k th nghim Ontology cho trng i hc Cng Ngh bng

cng c Protege 3.3.1 [68]. Vic pht trin mt Ontology, bao gm cc bc sau:

- nh ngha cc lp trong Ontology.

- Xp xp cc lp theo mt trt t lp cha lp con.

- nh ngha cc thuc tnh, miu t cc gi tr cho cc thuc tnh ny.

- in cc gi tr vo cc thuc tnh cho cc i tng.

Di y, chng ti trnh by cch thit k Ontology th nghim v trng i

hc Cng Ngh.


35

4.3.1 Thit k cc lp trong Ontology

Ty thuc vo cch thit k i vi Ontology, c th thit k cc lp mt cch

ring r hoc c th thit k phn cp. Sau khi nghin cu v phn tch cc khi nim

c th lin quan ti trng i hc Cng Ngh, chng ti a ra cc khi nim v cc

lp trong Ontology (hnh 4.3).

- Trng: lp tng quan trong Ontology.

- B_mn: is-a-subclass-of trng, c cc i tng: cng_ngh_phn_mm,

khoa_hc_my_tnh, mng_my_tnh,

- Khoa: is-a-subclass-of trng, c cc i tng: cng_ngh_thng_tin,

in_t_vin_thng,

- Lp: is-a-subclass-of trng, c cc i tng: k50_khoa_hc_my_tnh,

k50_cng_ngh_phn_mm, v l lp con ca lp trng.

- Mn: is-a-subclass-of trng, c cc i tng: hc_my, x_l_nh,

x_l_ngn_ng_t_nhin, _ha_my_tnh,

- Person: is-a-subclass-of trng, lp ny m t cc i tng v ngi, person

is-a-superclass-of ging_vin, person is-a-superclass-of sinh_vin.

- Ging_vin: is-a-subclass-of person, c i tng l cc ging vin ca trng.

- Sinh_vin: is-a-subclass-of person, c i tng l sinh vin ca trng, chng

hn: nguyn_quc_i, nguyn_quc_t, nguyn_b_t,

- Phng_th_nghim: is-a-subclass-of trng.

- which: bao gm cc khi nim v chc v, hc hm, hc v,

- Chc_v: is-a-subclass-of which, c cc i tng nh: hiu_trng,

trng_phng, lp_trng,

- Hc_hm: is-a-subclass-of which, c cc cc i tng: gio_s, ph_gio_s.

- Hc_v: is-a-subclass-of which, c hai i tng: thc_s, tin_s.

- M: is-a-subclass-of which, c cc i tng l m ca sinh vin: s0520097,

- Qu: is-a-subclass-of which, c cc i tng: h_ni, hi_dng,

bc_giang,

Hnh 4.3, chng ti m t cc lp c thit k trong Ontology bi Protege.


36

Hnh 4.3. Cc lp trong Ontology v trng i hc

4.3.2 Thit k thuc tnh trong Ontology

Trong Protege, mi quan h gia cc i tng ca cc lp c m t thng qua

cc thuc tnh. Cc thuc tnh ny c phn vo cc loi nh Functional (mt i

tng ch c th lin kt ti mt i tng khc qua thuc tnh ny), InverseFunctional

(thuc tnh ny c thuc tnh o ngc), Transitive (thuc tnh bc cu), Symmetric.

Cc thuc tnh c thit k trong Ontology bi Protege c hai trng l

domain v range. Hai trng ny dng m t cc lp trong Ontology lin quan

vi nhau thng qua thuc tnh . Mi thuc tnh s lin kt cc i tng trong cc

lp c t trong trng domain ti cc i tng trong cc lp c t trong

trng range. Lp con c tha k thuc tnh t cc lp cha ca n.


37

Trong qun trnh phn tch v nghin cu cc mi quan h lin, chng ti thit k

m t mt s quan h thng qua cc thuc tnh (hnh 4.4).

Hnh 4.4. Cc thuc tnh trong Ontology v trng i hc

Sau khi thit k xong cc lp, cc thuc tnh, cng vi cc i tng trong

mi lp. Chng ti in gi tr tng ng cho lin kt i vi mi i tng da the o

thuc tnh. Chng hn:

nguyn_quc_i hc k50_khoa_hc_my_tnh

nguyn_quc_i c_qu h_ni,

Thit k Ontology cn mt qu trnh lu di, nghin cu cc khi nim, phn tch

cc mi quan h cn chnh xc. Sau , chng ti p dng Ontology th nghim ny

cho h thng, ri nh gi hot ng ca h thng da vo cc cu hi c a ra.


38

4.4 nh x Ontology

nh x Ontology l nn tng trong h thng hi p ting Vit ca chng ti.

Cu hi u vo s c phn tch di dng b ba biu din trung gian bi thnh

phn x l cu hi [1], b ba biu din trung gian ny l u vo cho nh x Ontology.

nh x Ontology hnh thnh nn cc b ba m t cc khi nim, i tng cng vi

mi quan h tng thch vi Ontology. Thnh phn trch chn cu tr li s dng cc

b ba m t ny a ra cu tr li ng ngha tt nht c th ti ngi s dng.

to b ba m t cc khi nim, quan h v i tng tng ng vi Ontology,

trc tin, t b ba biu din trung gian thu c do [1], nh x Ontology s dng tp

t ng ngha i vi tng thnh phn ca b ba. Sau , cc thut ng c so

khp vi cc khi nim v i tng bn trong Ontology. Nu so khp khng thnh

cng, nh x Ontology s dng thut ton khong cch xu tm cc khi nim v

i tng tng t trong Ontology. Nu thut ton khong cch xu tr li nhiu hn

mt kt qu, khi y xy ra nhp nhng v ngha ca cc thut ng, th h thng a ra

tng tc vi ngi dng, yu cu la chn khi nim hoc i tng thch hp.

Sau khi tm c cc thut ng ch khi nim v i tng tng ng trong

Ontology, da vo chng, nh x Ontology tm kim cc mi quan h so khp vi

quan h u vo. Nu so khp khng c, nh x Ontology s dng thut ton

khong cch xu hoc tng tc vi ngi s dng. Khi nh x Ontology tm c

quan h tng ng trong Ontology, h thng hnh thnh cc b ba m t cc khi

nim, i tng cng mi quan h ph hp vi Ontology. Cc b ba thu u vo cho

thnh phn trch chn cu tr li a ra cu tr li ng ngha nht c th.

Thnh phn nh x Ontology x l ty theo tng trng hp c th, i vi tng

loi cu hi khc nhau c cch x l khc nhau. Cc loi cu hi c phn lm hai

dng, cu hi n gin v cu hi phc tp. Cc cu hi dng n gin c phn loi:

- sinh vin no hc lp k50 khoa hc my tnh NORMAL: (sinh vin,

hc, lp k50 khoa hc my tnh) nh x Ontology (sinh_vin, hc,

k50_khoa_hc_my_tnh).

- m ca Nguyn Quc i l g UNKN_TERM: (?, m, Nguyn Quc

i) nh x Ontology (m, c_m, nguyn_quc_i).


39

- Nguyn Quc i c a ch u UNKN_TERM: (?, a ch, Nguyn

Quc i) nh x Ontology (?, c_a_ch, nguyn_quc_i).

- lp k50 khoa hc my tnh c nhng sinh vin no UNKN_REL: (sinh

vin, ?, lp k50 khoa hc my tnh) nh x Ontology (sinh_vin, hc |

c_sinh_vin, k50_khoa_hc_my tnh).

- Nguyn Quc i c qu H ni phi khng AFFIRM_NEG:

(Nguyn Quc i, c qu, H Ni) nh x Ontology (nguyn_quc_i,

c_qu, h_ni).

i vi cc cu hi phc tp, khi chng c phn tch bi [1], th thu c b

ba biu din trung gian quan h bc ba, v c phn loi THREETERM. Ty vo

tng cu hi, b ba ny c th thiu thut ng u, hoc thiu quan h, hoc y

bn thnh phn. Sau khi nh x Ontology kt thc, h thng thu c hai b ba m t

tng ng vi Ontology. Chng hn:

sinh vin no hc lp khoa hc my tnh ca trng i hc cng ngh?

(sinh vin, hc, lp khoa hc my tnh, trng i hc cng ngh) nh x Ontology

(sinh_vin, hc, k50_khoa_hc_my_tnh) v (sinh_vin, hc,

i_hc_cng_ngh).

Di y, chng ti m t cch x l ca thnh phn nh x Ontology i vi

tng loi cu hi c th. Trc ht, chng ti gii thiu cch x l i vi cu hi n

gin, t , chng ti m t hot ng ca nh x Ontology i vi cu hi phc

tp.

4.4.1 nh x Ontology cho cu hi n gin

Cc cu hi sau khi c phn tch bi thnh phn x l cu hi ngn ng t

nhin [1], c xp vo cc loi tng ng. y, trong mc ny, chng ti m t i

vi mt s loi cu hi nh NORMAL, UNKN_TERM, UNKN_REL,

AFFIRM_NEG. Cc cu hi c biu din bi mt b ba quan h bc hai gia hai

thut ng, v b ba biu din ny l u vo cho nh x Ontology. Nhng ty vo tng

loi cu hi m nh x Ontology s c cch tm kim thut ng thch hp trong

Ontology. nh x Ontology x l i vi cc loi cu hi n gin ny c m t

nh hnh 4.5.


40

Hnh 4.5. Tng quan v nh x Ontology i vi cu hi n gin

Trong m hnh tng quan ny (hnh 4.5), c s tri thc Ontology c lu tr

trong Sesame Server. nh x Ontology ly tt c cc thng tin v cc khi nim (m t

cc lp), cc i tng, v cc thuc tnh m t quan h trong Ontology. Cc thng tin

ny c s dng so khp vi b ba u vo. Nu qu trnh so khp khng thnh

cng th nh x Ontology s dng thut ton khong cch xu tm cc khi nim

(hoc cc i tng, cc quan h trong Ontology) tng t vi cc thnh phn trong

b ba u vo. Nu thut ton khong cch xu tr li nhiu hn mt gi tr, tc l

nhp nhng xy ra, th nh x Ontology yu cu tng tc vi ngi dng la chn

thng tin thch hp tng ng vi Ontology.

Vi mt u vo l b ba biu din trung gian (quan h bc hai gia hai thut

ng) (hnh 4.5), cc thnh phn ca b ba c tin x l v s dng tp t ng ngha

so khp vi cc khi nim (cc lp), cc i tng v cc quan h trong Ontology.

nh x Ontology trc tin s so khp cc thut ng tm kim thut ng tng ng

trong Ontology. Cc thut ng c th mang ni dung ch v mt khi nim hoc mt

i tng c th no .

So khp thng tin trong Ontology

Tin x l & tp t ng ngha



Thut_ng_1

Thut_ng_2

Tp quan h


Tin x l & tp t ng ngha Quan_h

B

ba

biu

din

trung

gian

Thut ng 1

Quan h

Thut ng 2

Thut ton khong cch xu

Tng tc ngi dng

Thng tin trong Ontology


41

Nu vic so khp khng thnh cng, nh x Ontology s dng thut ton khong

cch xu tm cc khi nim (hoc cc i tng) tng t trong Ontology. Nu gi

tr so snh tng t gia hai khi nim (hoc gia hai i tng) ln hn ngng

cho trc th thut ton tr li khi nim (hoc i tng) tng ng . Hoc nu thut

ton khong cch xu tr li nhiu hn mt kt qu, khi , nhp nhng v ngha ca

cc thut ng vn xy ra. V d, khi thut ton khong cch xu so snh lp khoa hc

my tnh vi cc i tng trong Ontology. Khi y, s nhp nhng xy ra khi kt qu

ca thut ton tr li i tng k50_khoa_hc_my_tnh l thc th ca lp lp v

i tng khoa_hc_my_tnh l i tng ca lp b_mn trong Ontology. Lc

ny, nh x Ontology a ra yu cu tng tc vi ngi dng la chn thut ng

tng ng. Sau khi ngi dng phn hi li , h thng tm c thut ng cn thit ph

hp vi Ontology. Cc thut ng ny chnh l cc thut ng ch khi nim biu din

mt lp trong Ontology, hoc l cc thut ng ch i tng thuc v mt lp no

trong Ontology.

Da vo cc thut ng va tm c, nh x Ontology tm tt c cc quan h gia

hai thut ng ny. Sau , nh x Ontology nu so khp quan h khng thnh cng th

s dng thut ton khong cch xu tm quan h tng ng. Nu nhp nhng v

ngha xy ra do thut ton khong cch xu tr li nhiu hn mt kt qu, th h thng

a ra yu cu tng tc vi ngi s dng. Sau bc ny, nh x Ontology tm c

quan h thch hp gia hai thut ng trong Ontology. Nhng ty thuc vo tng loi

cu hi, chng hn nh cu hi UNKN_TERM (thiu thut ng u tin), c trng

hp tm c mi quan h thng qua thut ton khong cch xu, nhng cng c

trng hp chnh cm t miu t quan h trong cu li l thut ng ch khi nim m

t mt lp no trong Ontology.

Chng ti s a ra v d c th cho tng trng hp xem xt cch gii quyt

ca thnh phn nh x Ontology. Nh vy, kt thc qu trnh nh x Ontology, hnh

thnh b ba m t cc khi nim, i tng v quan h ph hp vi Ontology. B ba

m t ny l u vo cho thnh phn trch chn cu tr li a ra cu tr li ng ngha

tt nht c th ti ngi dng. Di y, miu t cch x l ca h thng i vi

thnh phn nh x Ontology, chng ti a ra mt s v d v tng loi cu hi v

cch x l i vi chng.


42

4.4.1.1 nh x Ontology i vi loi cu hi NORMAL

u tin, vi loi cu hi NORMAL miu t bi mt b ba c to thnh do

mt mi quan h nh phn r rng gia hai thut ng xc nh. V d vi cu hi:

thy gio no ging dy lp k50 khoa hc my tnh?

B biu din trung gian l b ba u vo cho nh x Ontology c cho di

dng (thy gio, ging dy, lp k50 khoa hc my tnh). Trc tin, nh x Ontology

tin x l v s dng tp t ng ngha i vi cc thnh phn ca b ba. Sau , nh

x Ontology nhn bit c thut ng thy gio chnh l thut ng ch khi nim

ging_vin m t lp ging_vin trong Ontology. nh x Ontology s dng thut

ton khong cch xu i vi lp k50 khoa hc my tnh th nhn c thut ng

ch i tng k50_khoa_hc_my_tnh l thc th trong lp lp trong Ontology.

Tip n, thnh phn nh x Ontology s tm cc quan h lin kt gia lp

ging_vin v lp lp trong Ontology. Sau , t tp quan h tm c, so khp

vi thut ng ging dy, nh x Ontology tm c thut ng ch quan h

ging_dy trong Ontology. nh x Ontology hnh thnh b ba m t l (ging_vin,

ging_dy, k50_khoa_hc_my_tnh) tng ng vi Ontology, t thnh phn trch

chn cu tr li a ra cu tr li ng ngha tt nht c th ti ngi dng (hnh 4.6).

Hnh 4.6. V d hi p i vi loi cu hi NORMAL


43

4.4.1.2 nh x Ontology i vi loi cu hi UNKN_REL

Tip n, hiu r hot ng ca thnh phn nh x Ontology, chng ti xem

xt loi cu hi thiu mi quan h trong cu v c phn loi UNKN_REL bi

thnh phn x l cu hi ngn ng t nhin [1]. Xt cu hi:

trng i hc cng ngh c hc sinh no?

Cu hi trch ra b ba di dng (hc sinh, ?, trng i hc cng ngh). Thut

ng hc sinh sau khi c tin x l, v s dng tp t vng ng ngha th c

nhn bit l sinh_vin biu din cho lp sinh_vin trong Ontology. Thut ng

trng i hc cng ngh c nhn bit l i tng i_hc_cng_ngh ca lp

trng trong Ontology bi vic dng thut ton khong cch xu.

Hnh 4.7. nh x Ontology tng tc vi ngi dng i vi loi cu hi UNKN_REL

Do khng c mi quan h c nhn bit trong trng hp ny, v vy h thng

xt tt c cc mi quan h gia hai lp trong Ontology l sinh_vin v trng, v

a ra la chn ti ngi dng yu cu v quan h mong mun gia sinh_vin v

i_hc_cng_ngh (hnh 4.7). Ngi dng a li phn hi ti h thng mi quan

h la chn l hc, hoc c_sinh_vin, hoc la chn c hai quan h. Khi , nh

x Ontology hnh thnh b ba (sinh_vin, hc, i_hc_cng_ngh) hoc (sinh_vin,

c_sinh_vin, i_hc_cng_ngh). Cu tr li c a ra sau khi h thng gi thnh

phn trch chn cu tr li.


44

4.4.1.3 nh x Ontology i vi loi cu hi UNKN_TERM

Vi nhng cu hi sau khi phn tch bi [1] th thiu thut ng u trong b ba,

c phn loi UNKN_TERM. y, chng ti a ra cc v d miu t r qu

trnh x l ca thnh phn nh x Ontology i vi cc cu hi ny:

- m sinh vin ca Nguyn Quc i l g?

- Nguyn Quc i c m sinh vin l g?

- sinh vin c a ch u?

- a ch ca sinh vin l g?

i vi hai cu hi u tin, thnh phn x l cu hi ngn ng t nhin phn

tch [1] v a ra b ba (?, m sinh vin, Nguyn Quc i). Sau khi b ba c tin

x l, nh x Ontology nhn bit m sinh vin l thut ng m da vo tp t

ng ngha. Da vo thut ton khong cch xu, h thng nhn bit c

nguyn_quc_i l thc th trong lp sinh_vin ca Ontology. Lc ny, nh x

Ontology s dng thut ton khong cch xu gia m v cc quan h ca lp

sinh_vin trong Ontology, v m c nhn bit khng tng t vi bt k mi

quan h no. M nh x Ontology li nhn ra l khi nim m biu din lp m

trong Ontology. Sau , h thng tm cc mi quan h gia lp m v lp

sinh_vin trong Ontology, v c mi quan h c_m gia hai lp ny. nh x

Ontology hnh thnh b ba m t (m, c_m, nguyn_quc_i). Cu tr li cho cu

hi c thnh phn trch chn cu tr li a ra ti ngi dng (hnh 4.8)

Hnh 4.8. V d hi p i vi loi cu hi UNKN_TERM


45

Hnh 4.9. V d hi p i vi loi cu hi UNKN_TERM

i vi hai cu hi sau, b ba u vo cho nh x Ontology l (?, a ch, sinh

vin). nh x Ontology nhn bit c thut ng ch khi nim sinh_vin biu din

cho lp sinh_vin trong Ontology. Lc ny, khi s dng thut ton khong cch xu

so snh a ch vi cc mi quan h ca lp sinh_vin trong Ontology, nh x

Ontology thu c thut ng ch quan h c_a_ch. nh x Ontology hnh thnh

b ba m t (?, c_a_ch, sinh_vin) tng ng vi Ontology. Thnh phn trch chn

cu tr li a ra cu tr li ti ngi dng (hnh 4.9).

Cc cu hi c x l bi thnh phn x l cu hi [1], do vy, chng ti hon

ton xem xt c cu hi mun hi v vn g, hi v ngi, v v tr Da trn

, chng ti c thm cch x l ph hp vi tng loi cu hi. Xem xt cu hi:

hc sinh ca trng i hc cng ngh l ai?

Thnh phn x l cu hi ngn ng t nhin [1] cho bit loi cu hi l

UNKN_TERM v loi t hi l QU Who, th h thng nhn bit c cu hi

s cp ti person no (c th l sinh_vin | ging_vin trong thit k

Ontology). Do u vo cho nh x Ontology l (person, hc sinh, trng i hc

cng ngh). B ba ny c tin x l v s dng tp t ng ngha. Sau khi so khp

v s dng thut ton khong cch xu, thnh phn nh x Ontology x l xong, thu

c u ra l b ba m t (person, c_sinh_vin, i_hc_cng_ngh) tng ng vi

Ontology.


46

4.4.1.4 nh x Ontology i vi loi cu hi AFFIRM_NEG

H thng m chng ti gii thiu cn x l vi cu hi dng ng sai. Chng

hn, vi cu hi:

Nguyn Quc i hc trng i hc cng ngh phi khng?

Cu hi ny c thnh phn x l cu hi ngn ng t nhin [1] phn loi vo

loi cu hi AFFIRM_NEG (loi cu hi ng sai) v b ba u vo cho nh x

Ontology l (Nguyn Quc i, hc, trng i hc cng ngh). Tng t trn, nh x

Ontology s dng thut ton khong cch xu tm thut ng thch hp, th nhn

c thut ng ch i tng nguyn_quc_i l thc th ca lp sinh_vin v

thut ng ch i tng i_hc_cng_ngh l thc th ca lp trng trong

Ontology. Tm cc mi quan h gia hai lp sinh_vin v trng trong Ontology.

Sau , h thng so khp vi quan h ca b ba u vo, nhn bit thut ng ch quan

h hc trong Ontology. nh x Ontology hnh thnh b ba m t (nguyn_quc_i,

hc, i_hc_cng_ngh), t thnh phn trch chn cu tr li a ra cu tr li

tng ng ti ngi dng (hnh 4.10).

Hnh 4.10. V d hi p i vi loi cu hi AFFIRM_NEG


47

4.4.2 nh x Ontology i vi loi cu hi THREETERM

Cc cu hi phc tp sau khi c phn tch bi thnh phn x l cu hi [1]

c phn loi THREETERM, v thu c b biu din trung gian di dng quan

h bc ba gia cc thut ng. V nh x Ontology phi x l tm cc quan h gia

cc thut ng vi nhau. Thnh phn nh x Ontology kt thc s a ra hai b ba m

t cc khi nim, i tng v quan h tng ng trong Ontolgy. V hai b ba ny

c s dng l u vo cho thnh phn trch chn cu tr li. Qu trnh x l ca nh

x Ontology c m t bi hnh 4.11.

Hnh 4.11. Tng quan nh x Ontology vi loi cu hi THREETERM

Tp quan h

Thut ton khong cch xu

Tng tc ngi dng

Thng tin trong Ontology

Quan_h_2

B

ba

biu

din

trung

gian

Thut ng 1

Quan h

Thut ng 2

Thut ng 3









Quan_h_1

Thut_ng_1

Thut_ng_2

Thut_ng_3


48

Tng t nh nh x Ontology i vi cu hi n gin, h thng lu tr c s

tri thc Ontology trong Sesame Server. T hnh 4.11, nh x Ontology ly tt c cc

thng tin v cc khi nim, cc i tng, v quan h trong Ontology. Cc thng tin

ny c s dng so khp vi b ba u vo. Nu qu trnh so khp khng thnh

cng th nh x Ontology s dng thut ton khong cch xu tm cc khi nim

(hoc cc i tng, cc quan h trong Ontology) tng t vi cc thnh phn trong

b ba u vo. Nu thut ton khong cch xu tr v nhiu hn mt gi tr, th nhp

nhng xy ra, v nh x Ontology yu cu tng tc ngi dng la chn thng tin

tng ng vi Ontology.

Cc cu hi trong cc trng hp ny c x l bi [1], c phn loi

THREETERM, v c biu din bi b ba quan h bc ba gia cc khi nim. Cc

thut ng trong b ba mang thng tin v cc khi nim hoc v cc i tng c th

no trong Ontology, cn quan h th m t lin quan gia cc thut ng ny. Ty

thuc vo tng trng hp c th, c trng hp b ba quan h bc ba thiu thut ng

u, hoc cng c trng hp thiu mt quan h gia cc thut ng.

u tin, vi cc thut ng, da vo tin x l v tp t ng ngha, nh x

Ontology s tm cc khi nim v i tng tng ng trong Ontology. Nu so khp

khng c, thnh phn nh x Ontology s dng thut ton khong cch xu tm cc

khi nim v i tng thch hp nht trong Ontology. Nu nhp nhng xy ra m nh

x Ontology khng x l c, th a ra yu cu tng tc vi ngi dng la

chn thng tin tng ng vi Ontology.

Sau khi nhn c cc thut ng tng thch, thnh phn nh x Ontology s

dng hai thut ng u tm cc mi quan h gia chng so khp vi quan h u

vo. Nu khng, nh x Ontology s dng thut ton khong cch xu tm quan h

tng ng trong Ontology, nu thut ton tr li nhiu hn mt kt qu th a ra la

chn ti ngi dng. Khi , nh x Ontology s hnh thnh b ba m t th nht t

cc thut ng v quan h tng ng va tm c gia chng.

Tip n, nh x Ontology da vo thut ng u (hoc thut ng th hai ty

thuc trng hp c th) v thut ng cui tm quan h gia chng trong Ontology.

Sau , nh x Ontology yu cu ngi dng la chn quan h thch hp. Sau khi mi

quan h mong mun c ngi s dng phn hi, thnh phn nh x Ontology hnh

thnh b ba m t th hai.


49

Thnh phn nh x Ontology kt thc a ra hai b ba m t cc khi nim, cc

i tng v cc quan h tng ng trong Ontology. V m t hot ng ca h

thng i vi cc cu hi ny, chng ti a ra cc v d thy r qu trnh m thnh

phn nh x Ontology x l ra sao ty vo tng trng hp c th.

Trc tin, vi cu hi c thnh phn x l cu hi ngn ng t nhin x l

[1] v cho u ra l mt b biu din trung gian ba thut ng v quan h, v nh x

Ontology ly chng lm u vo tm thng tin tng ng vi Ontology. Cu hi:

hc sinh no hc lp khoa hc my tnh ca trng i hc cng ngh?

B ba quan h bc ba hnh thnh bi [1] l (hc sinh, hc, lp khoa hc my tnh,

trng i hc cng ngh). B ba sau khi c tin x l v s dng tp t ng

ngha, c so khp vi cc khi nim v i tng trong Ontology. nh x Ontology

nhn bit c thut ng ch khi nim sinh_vin m t lp sinh_vin trong

Ontology. Khi s dng thut ton khong cch xu i vi lp khoa hc my tnh

tm i tng tng ng trong Ontology th c nhp nhng xy ra do thut ton tr li

hai gi tr. Lc ny, nh x Ontology a ti ngi dng hai la chn l thut ng ch

i tng k50_khoa_hc_my_tnh l thc th ca lp lp hoc thut ng

khoa_hc_my_tnh l thc th ca lp b_mn trong Ontology.

Sau khi ngi dng la chn thut ng mong mun, chng hn, la chn

k50_khoa_hc_my_tnh. Sau , tm quan h cho sinh_vin v

k50_khoa_hc_my_tnh, thnh phn nh x Ontology da vo lp sinh_vin v

lp lp trong Ontology, tm tt c cc mi quan h gia hai lp ny ri so khp vi

quan h hc c thut ng ch quan h hc trong Ontology. nh x Ontology

hnh thnh c b ba m t u tin (sinh_vin, hc, k50_khoa_hc_my_tnh).

Tip n, h thng s tm quan h cho sinh_vin v i_hc_cng_ngh da

vo lp sinh_vin v lp trng, nh x Ontology s tm cc mi quan h gia hai

lp ny trong Ontology. Sau , h thng a li cho ngi dng la chn quan h

mong mun gia sinh_vin v i_hc_cng_ngh. Chng hn l mi quan h

c chn l hc (c th la chn nhiu quan h cng lc theo ngi dng). T

, nh x Ontology a ra b ba m t th hai l (sinh_vin, hc,

i_hc_cng_ngh). Sau khi nh x Ontology kt thc, h thng gi thnh phn trch

chn cu tr li, da vo hai b ba m t ny, a ra cu tr li ti ngi s dng.


50

i vi cu hi trn, b ba m t th hai hnh thnh do thut ng u v thut

ng cui. Nhng trong trng hp di y, nh x Ontology li da vo thut ng

th hai v thut ng cui hnh thnh b ba m t th hai. Vi cu hi:

sinh vin ca lp ca trng i hc cng ngh

201_2017

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