bai giang tri tuen han tao
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TS. Nguyn nh ThunKhoa Cng nghThng tin
i hc Nha TrangEmail: thuanvinh122@gmail.com
TR TUNHN TO
Artificial Intelligence
Nha Trang 8-2007
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Slide 2
Noi dung mon hoc
Chng 1: Gii thiu
Mu Lnh vc nghin cu ca AI
ng dng ca AI
Cc vn t ra
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Slide 3
Noi dung mon hoc (tip)
Chng 2:Tm kim trn khng gian trng thi
Bi ton tm kim Gii thut tng qut Depth first search (DFS) Breath first search (BFS)
Chng 3:Tm kim theo Heuristic Gii thiu vHeuristic
Tm kim theo heuristic Gii thut Best first search (BFS), Gii thut AT, AKT, A* Chin lc Minimax, Alpha Beta
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Slide 4
Noi dung mon hoc (tip)
Chng 4:Biu din tri thc
Bba i tng Thuc tnh Gi tr Cc lut dn Mng ngngha Frame
Logic mnh , Logic vt Thut gii Vng Ho, Thut gii Robinson
Chng 5: My hc
Cc hnh thc hc Thut gii Quinland Hc theo bt nh
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Slide 5
Thc hnh &Ti liu tham kho
Thc hnh Prolog / C++ / Pascal
Cc gii thut tm kim Biu din tri thc
Bi tp ln
Ti liu tham kho Bi ging Tr tunhn to TS Nguyn nh Thun
Gio trnh Tr tunhn to - GS Hong KimHQGTPHCM
Tr tunhn toPGS Nguyn Thanh ThyH Bch Khoa HNi Artificial Inteligent George F. Luget & Cilliam A. Stubblefied
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TS. Nguyn nh ThunKhoa Cng nghThng tin
i hc Nha TrangEmail: thuanvinh122@gmail.com
Chng 1: GII THIEU
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Slide 7
1.1 Mu
Tr tul g:
Theo tin Bch khoa ton thWebster: Tr tul khnng:
Phn ng mt cch thch hp li nhng tnh hung
mi thng qua iu chnh hnh vi mt cch thchhp.
Hiu r mi lin hgia cc skin ca thgii bn
ngoi nhm a ra nhng hnh vi ph hp tc mc ch.
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Slide 8
SThng Minh
Khi nim vtnh thng minh ca mt i
tng thng biu hin qua cc hot ng:Shiu bit v nhn thc c tri thc
Sl lun to ra tri thc mi da trn tri thc c
Hnh ng theo kt quca cc l lun
Knng (Skill)
TRI THC ???
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Slide 9
Tri thc (Knowledge)
Tri thc l nhng thng tin cha ng 2 thnh phn Cc khi nim:
Cc khi nim cbn: l cc khi nim mang tnh quy c Cc khi nim pht trin: c hnh thnh tcc khc nim cbn
thnh cc khi nim phc hp phc tp hn.
Cc phng php nhn thc: Cc qui lut, cc thtc Phng php suy din, l lun,..
Tri thc l iu kin tin quyt ca cc hnh xthng minh haySthng minh
Tri thc c c qua sthu thp tri thc v sn sinh tri thc
Qu trnh thu thp v sn sinh tri thc l hai qu trnh song song vni tip vi nhau khng bao gichm dt trong mt thc th
Thng Minh
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Slide 10
Tri thc Thu thp v sn sinh
Thu thp tri thc: Tri thc c thu thp tthng tin, l kt quca mt qu
trnh thu nhn dliu, xl v lu tr. Thng thng qutrnh thu thp tri thc gm cc bc sau: Xc nh lnh vc/phm vi tri thc cn quan tm
Thu thp dliu lin quan di dng cc trng hp cth.
Hthng ha, rt ra nhng thng tin tng qut, i din cho cctrng hp bit Tng qut ha.
Xem xt v gili nhng thng tin lin quan n vn cn quantm , ta c cc tri thc vvn .
Sn sinh tri thc: Tri thc sau khi c thu thp sc a vo mng tri thc c.
Trn cs thc hin cc lin kt, suy din, kim chng sn sinh ra
cc tri thc mi.
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Slide 11
Tri thc Tri thc siu cp
Tr thc siu cp (meta knowledge) hay Tri thc vTri thc L cc tri thc dng :
nh gi tri thc khc
nh gi kt quca qu trnh suy din
Kim chng cc tri thc mi
Phng tin truyn tri thc: ngn ngtnhin
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Slide 12
Hanh x thong minh Ket luan
Hnh xthng minh khng n thun l cc hnh ng nhl ktquca qu trnh thu thp tri thc v suy lun trn tri thc.
Hnh xthng minh cn bao hm Stng tc vi mi trng nhn cc phn hi Stip nhn cc phn hi iu chnh hnh ng - Skill Stip nhn cc phn hi hiu chnh v cp nht tri thc
Tnh cht thng minh ca mt i tng l stng hp ca c3yu t: thu thp tri thc, suy lun v hnh xca i tng trn trithc thu thp c. Chng ha quyn vo nhau thnh mt ththng nht SThng Minh
Khng thnh gi ring lbt kmt kha cnh no ni vtnh thng minh. THNG MINH CN TRI THC
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Slide 13
1.2 i tng nghien cu cua AI
AI l lnh vc ca Cng nghthng tin, c chc nng nghincu v to ra cc chng trnh m phng hot ng tduy ca
con ngi. Tr tunhn to nhm to ra My ngi?
Mc tiu
Xy dng l thuyt vthng minh gii thch cc hot ngthng minh
Tm hiu cchsthng minh ca con ngi Cchlu trtri thc
Cchkhai thc tri thc Xy dng cchhin thc sthng minh
p dng cc hiu bit ny vo cc my mc phc vcon
ngi.
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Slide 14
1.2 i tng nghien cu cua AI(tip)
AI l ngnh nghin cu vcch hnh x thng minh(intellgent behaviour) bao gm: thu thp, lu tr tri
thc, suy lun, hot ng v knng.i tng nghin cu l cc hnh x thng minh
chkhng phi l sthng minh.
Gii quyt bi ton bng AI l tm cch biu din trithc, tm cch vn dng tri thcgii quyt vn v tm cch bsung tri thc bng cch pht hin tri
thc tnhng thng tin sn c (my hc)
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Slide 15
1.3 Lch spht trin ca AI :Giai on cin
Giai on cin (1950 1965)C 2 kthut tm kim cbn:
Kthut generate and test : chtm c 1 p n/ chachc ti u.
Kthut Exhaustive search (vt cn): Tm tt cccnghim, chn la phng n tt nht.
(Bng nthp m(Bng nthp mnn vi m>=10)vi m>=10)
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Slide 16
Lch spht trin ca AI :Giai on vin vng
Giai on vin vng (1965 1975) y l giai on pht trin vi tham vng lm cho my hiu c
con ngi qua ngn ngtnhin. Cc cng trnh nghin cu tp trung vo vic biu din tri thc v
phng thc giao tip gia ngi v my bng ngn ngtnhin.
Kt qukhng my khquan nhng cng tm ra c cc phngthc biu din tri thc vn cn c dng n ngy nay tuy chatht tt nh: Semantic Network (mng ngngha)
Conceptial graph (thkhi nim) Frame (khung)
Script (kch bn)Vp phi trngi vnng lcVp phi trngi vnng lc
ca my tnhca my tnh
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Slide 17
Lch spht trin ca AI :Giai on hin i
Giai on hin i (t1975) Xc nh li mc tiu mang tnh thc tin hn ca AI:
Tm ra li gii tt nht trong khong thi gian chp nhn c. Khng cu ton tm ra li gii ti u
Tinh thn HEURISTIC ra i v c p dng mnh mkhcphc bng nthp.
Khng nh vai tr ca tri thc ng thi xc nh 2 trngi ln lbiu din tri thc v bng nthp.
Nu cao vai tr ca Heuristic nhng cng khng nh tnh kh khn
trong nh gi heuristic.
Better than nothingBetter than nothingPht trin ng dng mnh m: Hchuyn gia,Hchun on,..
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Slide 18
1.4 Cc lnh vc ng dng
Game Playing: Tm kim / Heuristic
Automatic reasoning & Theorem proving: Tm kim / Heuristic Expert System: l hng pht trin mnh mnht v c gi trng
dng cao nht.
Planning & Robotic: cc hthng dbo, tng ha
Machine learning: Trang bkhnng hc tp gii quyt vn khotri thc:
Supervised : Kim sot c tri thc hc c. Khng tm ra ci mi.
UnSupervised:Thc, khng kim sot. C thto ra tri thc minhng cngnguy him v c thhc nhng iu khng mong mun.
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Slide 19
1.4 Cc lnh vc ng dng(tip)
Natural Language Understanding & Semantic modelling:Khngc pht trin mnh do mc phc tp ca biton cvtri thc & khnng suy lun.
Modeling Human perfromance: Nghin cu cchtchctr tuca con ngi p dng cho my.
Language and Environment for AI:Pht trin cng cv mitrng xy dng cc ng dng AI.
Neural network / Parallel Distributed processing: gii quytvn nng lc tnh ton v tc tnh ton bng kthutsong song v m phng mng thn kinh ca con ngi.
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Slide 20
ng dung AI
M hnh ng dng AI hin ti:
AI = Presentation & SearchAI = Presentation & Search Mc d mc tiu ti thng ca ngnh TTNT l xy dng mt chic my c
nng lc tduy tng tnhcon ngi nhng khnng hin ti ca tt ccc sn phm TTNT vn cn rt khim tn so vi mc tiu ra. Tuyvy, ngnh khoa hc mi mny vn ang tin bmi ngy v ang tra
ngy cng hu dng trong mt scng vic i hi tr thng minh ca conngi. Hnh nh sau sgip bn hnh dung c tnh hnh ca ngnh tr tunhn to.
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Slide 21
Cc bi ton
Xt cc bi ton sau:
1. i tin (Vt cn v Heuristic)
2. Tm kim chiu rng v su3. Tic tac toe.
4. ong du.
5. Bi ton TSP6. 8 puzzle.
7. Cvua
8. Ctng9. Ngi nng dn qua sng.
10. Con thv con co
11.
Con khv ni chui
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TS. Nguyn nh ThunKhoa Cng nghThng tin
i hc Nha TrangEmail: thuanvinh122@gmail.com
Chng 2: TM KIM TRN KHNGGIAN TRNG THI
(State Space Search)
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Slide 23
Bi ton tm kim
Tm kim ci g?
Biu din v tm kim l kthut phbin gii cc biton trong lnh vc AI
Cc vn kh khn trong tm kim vi cc bi tonAI c tvn phc tp
Khng gian tm kim ln
c tnh i tng tm kim thay i
p ng thi gian thc Meta knowledge v kt quti u
Kh khn vkthut
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Slide 24
Cu trc chung ca bi ton tm kim
Mt cch chung nht, nhiu vn -bi ton phc tp uc dng "tm ng i trong th" hay ni mt cch
hnh thc hn l "xut pht tmt nh ca mt th,tm ng i hiu qunht n mt nh no ".
Mt pht biu khc thng gp ca dng bi ton ny l:
Cho trc hai trng thi T0 v TG hy xy dng chui trng thiT0, T1, T2, ..., Tn-1, Tn = TG sao cho :
tha mn mt iu kin cho trc (thng l nhnht).
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Slide 25
2.2 Gii thut tng qut
K hiu:s nh xut pht
g:nh chn:nh ang xt
(n): tp cc nh c th i trc tip t nh n
Open: tp cc nh c th xt bc k tipClose: tp cc nh xt
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Slide 26
2.2 Gii thut tng qut (tip)
Begin
Open := {s};
Close := ;While (Open ) do
begin
n:=Retrieve(Open);if (n=g) then Return True;
Open := Open (n); // ((n) Close)
Close := Close {n};
end;
Return False;
End;
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Slide 27
V d:
Xt graph sau:
A
B C D
E F G
H I J
s = A l nh bt ug= G l nh ch
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Slide 28
2.3 Breath First Search V d
Xt graph sau:
A
B C D
E F G
H I J
{A}
{A, B}{A, B, C}
{A, B, C, D}
{A, B, C, D, E}
{A, B, C, D, E, F}
{A}
{B, C, D}
{C, D, E, F}{D, E, F, G}
{E, F, G}
{F, G, H, I}
{G, H, I, J}
{B, C, D}
{E, F}{F, G}
{H, I}
{J}
True
A
BC
D
E
FG
0
1
23
4
5
67
CloseOpen(n)nLn lp
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Slide 29
2.3 Breath First Search V d1
Xt graph sau:A->U
A
B C D
E F G
H I J
{A}
{A, B}{A, B, C}
{A, B, C, D}
{A, B, C, D, E}
{A, B, C, D, E, F}{A, B, C, D, E, F,G}
{A,B,C, D, E, F,G,H}
{A,B,C, D, E,F,G,H,I}
{A,B,C, D, E,F,G,H,I,J}
{A}
{B,C,D}
{C,D, E,F}{D,E, F,G}
{E, F, G}
{F, G, H, I}
{G, H, I, J}{H, I, J}
{I, J}
{J}
{B, C, D}
{E, F}{F, G}
{H, I}
{J}
FALSE
A
BC
D
E
FG
H
I
J
0
1
23
4
5
67
8
9
10
CloseOpen(n)nLn lp
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Slide 30
V d:
Xt graph sau:
A
B C D
E F G
H I J
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Slide 31
2.4 Depth First Search V d
Xt graph sau:
A
B C D
E F G
H I J
{A}
{A, B}
{A, B, E}
{A, B, E, H}
{A, B, E, H, I}
{A, B, E, H, I, F}{A, B, E, H, I, F,J}
{A,B,E,H,I, F,J,C}
{A}
{B, C, D}
{E, F, C, D}
{H, I, F, C, D}
{I, F, C, D}
{F, C, D}
{J, C, D}
{C, D}
{G, D}
{B, C, D}
{E, F}
{H, I}
{J}
{F, G}
True
A
B
E
H
I
F
J
C
G
0
1
2
3
4
5
6
7
8
9
CloseOpen(n)nLn lp
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Slide 32
Breath First vs Depth First
Breath First: openc tchc dng FIFO
Depth First: open c tchc dng LIFO
Hiu qu Breath First lun tm ra nghim c scung nhnht
Depth First thng cho kt qunhanh hn.
Kt qu BFS, DFS chc chn tm ra kt qunu c.
Bng nthp l kh khn ln nht cho cc gii thutny.Gii Php cho bng nthp??
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Slide 33
Tm Kim Rng
1. Open = [A]; closed = []2. Open = [B,C,D];
closed = [A]
2. Open = [C,D,E,F];closed = [B,A]3. Open = [D,E,F,G,H]; closed = [C,B,A]4. Open = [E,F,G,H,I,J]; closed = [D,C,B,A]5. Open = [F,G,H,I,J,K,L];closed = [E,D,C,B,A]
6. Open = [G,H,I,J,K,L,M];(v L c trong open);
closed = [F,E,D,C,B,A]
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Slide 34
Tm kim Su
1. Open = [A]; closed = []2. Open = [B,C,D]; closed = [A]3. Open = [E,F,C,D];closed = [B,A]
4. Open = [K,L,F,C,D];closed = [E,B,A]5. Open = [S,L,F,C,D];
closed = [K,E,B,A]6. Open = [L,F,C,D];
closed = [S,K,E,B,A]7. Open = [T,F,C,D];
closed = [L,S,K,E,B,A]8. Open = [F,C,D];
closed = [T,L,S,K,E,B,A]
9.
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Slide 35
Depth first search c gii hn
Depth first search c khnng lp v tn do cc trngthi con sinh ra lin tc. su tng v tn.
Khc phc bng cch gii hn su ca gii thut. Su bao nhiu th va?
Chin lc gii hn: Cnh mt su MAX, nhcc danh thchi ctnh
trc c snc nht nh
Theo cu hnh resource ca my tnh
Meta knowledge trong vic nh gii hn su.
Gii hn su => co hp khng gian trng thi => cthmt nghim.
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TS. Nguyn nh ThunKhoa Cng nghThng tin
i hc Nha TrangEmail: thuanvinh122@gmail.com
Chng 3: HEURISTIC SEARCH
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Slide 37
3.1 Gii thiu vHeuristic
Heuristic l g? Heuristic l nhng tri thc c rt ta tnhng kinh
nghim, trc gic ca con ngi. Heuristic c thl nhng tri thc ng hay sai.
Heuristic l nhng meta knowledge v thng ng.
Heuristic dng lm g? Trong nhng bi ton tm kim trn khng gian trng thi, c
2 trng hp cn n heuristic: Vn c thkhng c nghim chnh xc do cc mnh khng pht
biu cht chhay thiu dliu khng nh kt qu. Vn c nghim chnh xc nhng ph tn tnh ton tm ra nghim
l qu ln (hquca bng nthp)
Heuristic gip tm kim t kt quvi chi ph thp hn
H i i ( i )
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Slide 38
Heuristic (tip)
Thut gii Heuristic l mt s m rng khinim thut ton. N thhin cch gii bi ton
vi cc c tnh sau: Thng tm c li gii tt (nhng khng chc l
li gii tt nht)
Gii bi ton theo thut gii Heuristic thng ddng v nhanh chng a ra kt quhn so vi giithut ti u, v vy chi ph thp hn.
Thut gii Heuristic thng th hin kh t nhin,gn gi vi cch suy ngh v hnh ng ca conngi.
H i i ( i )
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Slide 39
Heuristic (tip)
C nhiu phng php xy dng mt thut gii Heuristic, trongngi ta thng da vo mt snguyn l cbn nhsau:
Nguyn l vt cn thng minh: Trong mt bi ton tm kim no , khi khnggian tm kim ln, ta thng tm cch gii hn li khng gian tm kim hocthc hin mt kiu d tm c bit da vo c th ca bi ton nhanh chngtm ra mc tiu.
Nguyn l tham lam (Greedy): Ly tiu chun ti u (trn phm vi ton cc)
ca bi ton lm tiu chun chn la hnh ng cho phm vi cc bca tngbc (hay tng giai on) trong qu trnh tm kim li gii.
Nguyn l tht: Thc hin hnh ng da trn mt cu trc ththp l cakhng gian kho st nhm nhanh chng t c mt li gii tt.
Hm Heuristic: Trong vic xy dng cc thut gii Heuristic, ngi ta thngdng cc hm Heuristic. l cc hm nh gi th, gi trca hm phthucvo trng thi hin ti ca bi ton ti mi bc gii. Nhgi trny, ta c thchn c cch hnh ng tng i hp l trong tng bc ca thut gii.
H i ti G d
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Slide 40
Heuristic Greedy
Bi ton i tin: i stin n thnh cc loi tin chotrc sao cho stl t nht
Bi ton hnh trnh ngn nht (TSP): Hy tm mt hnhtrnh cho mt ngi giao hng i qua n im khc nhau,mi im i qua mt ln v trvim xut pht sao cho
tng chiu di on ng cn i l ngn nht. Gisrng c con ng ni trc tip tgia hai im bt k. Vt cn: (n-1)! (Vi n ln ???)
Greedy 1: Mi bc chn i j sao cho j gn i nht trong nhngnh ni vi i cn li
Greedy 2: Mi bc chn i j sao cho i gn j nht trong nhngnh ni vi j cn li
V d TSP i 8
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Slide 41
V d: TSP vi n=8
0660690200900116047010108
66003904605709205403807
69039005209506003004306
2004605200740105050080059005709507400142010408404
11609206001050142007106403
470540300500104071007302
101038043080084064073001
87654321
V d TSP i 8
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Slide 42
V d: TSP vi n=8
*Vi Greedy 1:
1 7 6 2 8 5 4 3 1
Tng chi ph: 4540*Vi Greedy 2:
1 7 4 5 8 2 6 3 1
Tng chi ph: 3900
Bi ton 3: Bi ton t mu bn
Heuristic (tt)
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Slide 43
Heuristic (tt)
Heuristic dng nhthno trong tm kim? Tm kim trn khng gian trng thi theo chiu no? Su
hay rng? Tm theo Heuristic : Heuristic nh hng qu trnh tm
kim theo hng m n cho rng khnng t ti nghiml cao nht. Khng su cng khng rng
Kt quca tm kim vi Heuristic Vic tm kim theo nh hng ca heuristic c kt qutt
hay xu ty theo heuristic ng hay sai.
Heuristic c khnng bst nghim
Heuristic cng tt cng dn n kt qunhanh v tt.
Lm sao tm c Heuristic tt???Lm sao tm c Heuristic tt???
3 2 T ki ti (B t Fi t S h)
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Slide 44
3.2 Tm kim ti u (Best First Search)
OPEN : tp cha cc trng thi c sinh ra nhng cha c xt n (v ta chn mt trng thi khc). Thc ra, OPEN l mt loi hng i u tin(priority queue) m trong , phn tc u tin cao nht l phn ttt nht.
CLOSE : tp cha cc trng thi c xt n. Chng ta cn lu trnhngtrng thi ny trong bnhphng trng hp khi mt trng thi mi cto ra li trng vi mt trng thi m ta xt n trc .
Thut gii BEST-FIRST SEARCH
1.t OPEN cha trng thi khi u.2. Cho n khi tm c trng thi ch hoc khng cn nt no trong OPEN, thchin :
2.a. Chn trng thi tt nht (Tmax) trong OPEN (v xa Tmax khi OPEN)
2.b. Nu Tmax l trng thi kt thc th thot.2.c. Ngc li, to ra cc trng thi ktip Tk c thc ttrng thi Tmax.i vi mi trng thi ktip Tk thc hin : Tnh f(Tk); Thm Tk vo OPEN
3 2 Tm kim ti u (tip)
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Slide 45
3.2 Tm kim ti u (tip)
Thut gii BEST-FIRST SEARCH
Beginopen:={s};
While (open ) dobeginn:= Retrieve(Open) //Chn trng thi tt nht tOpen.if(n=g) then return Trueelse begin
To (n)for mi nt con m ca (n) do
Gn gi trchi ph cho mOpen:=Open{m};
end;Return False;
End;
Begin
Open := {s};
Close := ;
While (Open ) do
begin n:=Retrieve(Open);
if (n=g) then Return True;
Open := Open (n); // ((n) Close)
Close := Close {n};
end; Return False;
End;
3 2 Tm kim ti (tip)
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Slide 46
3.2 Tm kim ti u (tip)
- BFS kh n gin. Tuy vy, trn thc t, cng nh tm kimchiu su v chiu rng, him khi ta dng BFS mt cch trctip. Thng thng, ngi ta thng dng cc phin bn caBFS l AT, AKT v A*Thng tin vqu khv tng lai
-Thng thng, trong cc phng n tm kim theo kiu BFS,
tt fca mt trng thi c tnh da theo 2 hai gi trm tagi l l g v h. h chng ta bit, l mt c lng vchiph t trng thi hin hnh cho n trng thi ch (thng tintng lai). Cn g l "chiu di qung ng" i ttrng thi
ban u cho n trng thi hin ti (thng tin qu kh). Lu rng g l chi ph thc s(khng phi chi ph c lng).
3 3 Thut gii AT
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Slide 47
3.3 Thut gii AT
Phn bit khi nim g v h
3 3 Thut gii AT
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Slide 48
3.3 Thut gii AT
Thut gii AT l mt phng php tm kim theo kiu BFS vitt ca nt l gi trhm g tng chiu di con ng ittrng thi bt u n trng thi hin ti.
Beginopen:={s};While (open ) do
beginn:= Retrieve(Open) //Chn n sao cho g(n) nh nht tOpen.if(n=g) then return Trueelse begin
To (n)for mi nt con m ca (n) do
if (mOpen) thenBegin
g(m):=g(n)+Cost(n,m)Open:=Open{m};
endelse So snh g(m) va gNew (m) v cp nht
end;Return False;
3 3 Thut gii CMS (Cost Minimazation Search)
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Slide 49
3.3 Thut gii CMS (Cost Minimazation Search)
Thut gii CMS l mt phng php tm kim theo kiu BFS vi tt cant l gi trhm g v bsung tp Close: tp nh xt).Begin
open:={s}; close :=
While (open ) dobeginn:= Retrieve(Open) //Chn n sao cho g(n) nh nht tOpen.if(n=g) then return Trueelse begin
To (n)for mi nt con m ca (n) doif (mOpen) and (mClose) then
Beging(m):=g(n)+Cost(n,m)
Open:=Open{m};endelse So snh g(m) va gNew (m) v cp nht
close = close {n}end;
Return False;End
V d:
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Slide 50
V d:
Xt graph sau:
A
B C D
E F G
H I J
s = A l nh bt ug= J l nh ch
3520 30
1545
30
40
25 10
10
20
V d:
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Slide 51
V d:
Xt graph sau:
(E,60),(J,60)(J}F
(C,35), (D,30),(E,60),(F,65){E,F}B
(C,35),(E,60),(F,65)D
(E,60),(F,50),(G,45){F,G}C
(E,60),(F,50),(J,65){J}G
J
{(B,20), (C,35), (D,30)}{B,C,D}A1
{(A,0)}0
Open(n)nLn lp
s = A l nh bt ug= J l nh ch
DA
EBFC
GC
JF
CABA
A*
SauTrc
3 4 Thut gii AKT
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Slide 52
3.4 Thut gii A
(Algorithm for Knowlegeable Tree Search)
Thut gii AKT mrng AT bng cch sdng thm thng tin c lng h. ttca mt trng thi f l tng ca hai hm g v h.
Begin
open:={s};While (open ) do
beginn:= Retrieve(Open) //Chn n sao cho f(n) nh nht tOpen.if(n=g) then return True
else beginTo (n)for mi nt con m ca (n) do
Beging(m):=g(n)+Cost(n,m)
f(m):= g(m)+h(m);Open:=Open{m};
end;end;
Return False;
End;
3 5 Thut gii A*
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Slide 53
3.5 Thut gii A
Thut gii A*A* l mt phin bn c bit ca AKT p dng cho trng hp th.Thut gii A* c s dng thm tp hp CLOSE lu tr nhngtrng hp c xt n. A* mrng AKT bng cch bsung cchgii quyt trng hp khi "m" mt nt m nt ny c sn trongOPEN hoc CLOSE.
3.5 Thut gii A* (tip)
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Slide 54
3.5 Thut gii A (tip)
Beginopen:={s}; close:=;
While (open ) do
beginn:= Retrieve(Open) //sao cho f(n) min.if(n=g) then return path ts n gelse begin
To (n)for mi nt con m ca (n) do
case m ofm Open v m Close:
beginGn gi trheuristic cho mOpen:=Open{m};
end;
m Open:ifn c m bng mt path ngn hnthen Cp nht li m trong Open.
m Closeifn c m bng mt path ngn hnthen begin
Close:=Close-{m}
Open:=Open{m}end;
end; /*end case*/
Close:=Close{n}
end; / while/return false;End;
Hm lng gi Heuristic
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Slide 55
g g eu st c
Hm lng gi Heuristic l hm c lng ph tn i ttrng thihin ti n trng thi goal.
Csxc nh hm lng gi l da vo tri thc/kinh nghim thuthp c.
Hm lng gi cho kt qung (gn thc th) hay sai (xa gi trthc) sdn n kt qutm c tt hay xu.
Khng c chun mc cho vic nh gi mt hm lng giHeuristic. L do:
Khng c cu trc chung cho hm lng gi
Tnh ng/sai thay i lin tc theo tng vn cth Tnh ng/sai thay i theo tng tnh hung cthtrong mt vn
C thdng nhiu hm lng gi khc nhau theo tnh hung cn hm lng gi vcc hm lng gi.
Tr8 hay 15
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Slide 56
y
Trng thi ban u Trng thi ch Tr
15
Tr8
Cn biu din KGTT cho bi ton ny nhthno?
78910
615115141312
4321
567
48
321
38129
1513215610
741411
126
753
82
C 3 Tm kim khng gian trng thi
Thut gii A* V d
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Slide 57
g
l Xt bi ton 8 pusslevi goal l:
567
48
321
Heuristic 1: Tng sming sai vtrHeuristic 2: Tngkhong cch sai v tr
ca tng ming.
65
43
6557
461
382
567
41
382
57
461
382
Vic chn la hm Heuristic l kh khn v c ngha quyt nh i vi tc ca gii thut
Hm lng gi Heuristic Cu trc
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Slide 58
g g
Xt li hot ng ca gii thut Best First Search: Khi c 2 nt cng c gi trkvng t n mc tiu bng nhau th nt c
path tnt bt u n nt ngn hn sc chn trc nhvy nt ny
c gi trHeuristic tt hn. Hay ni cch khc hm lng gi Heuristic cho nt gn start hn l tt hn
nu kvng n goal l bng nhau.
Vy chn nt no nu kvng ca 2 nt khc nhau? Nt kvng tt hn
nhng xa start hay nt kvng xu hn nhng gn rootHm lng gi bao gm c2 v c cu trc:
F(n) := G(n) + H(n)
G(n): ph tn thc troot n nH(n): ph tn c lung heuristic tn n goal.
Thut gii A* V d
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Slide 59
g
l Xt v dl bi ton 8 puzzle vi:
57461
382
Bt u
56748
321
ch
Hm lng gi: F(n) = G(n) + H(n)Vi G(n): sln chuyn vtr thc hin
H(n): Sming nm sai vtrNt X c gi trheuristic tt hn nt Y nu F(x) < F(y).
Ta c hot ng ca gii thut Best First search trn nhhnh sau:
3.5 Thut gii A* (tip)
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Slide 60
Beginopen:={s}; close:=;
While (open ) dobegin
n:= Retrieve(Open) //sao cho f(n) min.if(n=g) then return path ts n gelse begin
To (n)for mi nt con m ca (n) do
case m ofm Open v m Close:
beginGn gi trheuristic cho mOpen:=Open{m};
end;
m Open:ifn c m bng mt path ngn hnthen Cp nht li m trong Open.
m Closeifn c m bng mt path ngn hnthen begin
Close:=Close-{m}
Open:=Open{m}end;
end; /*end case*/
Close:=Close{n}end; / while/return false;
End;
V d
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Slide 61
57
461
3821 State A
F(a) =0+4=4
57
461
382x State B
F(b) =1+5=6 56741
3822 State C
F(c) =1+3=4 57461
382x State D
F(D) =1+5=6
567
41
3823 State E
F(e) =2+3=5 567481
324 State F
F(f) =2+3=5 56741
382x State G
F(g) =2+4=6
567
412
38x State H
F(h) =3+3=6 56417
382x State I
F(i) =3+4=7
57
461
382
567
41
382
V d
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Slide 62
567
481
324 State F
F(f) =2+3=5
567
481
325 State J
F(j) =3+2=5 567481
32x State K
F(k) =3+4=7 56741
382y State Close
567
481
32y Close567
48
3216 State L
F(l) =4+1=5
567
481
32y State Close
567
48
3217 State M
F(m) =5+0=5 56487
321x State N
F(n) =5+1=7
The 8-puzzle searched by a production system with
l d t ti d d th b d 5
C3T
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Tr
chi
8-puzzle
loop detection and depth bound 5Tm
kim
khnggia
ntrngthi
Hot ng theo gii thut A*
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Slide 64
{}
{A4}{A4,C4}
{A4,C4,E5}
{A4,C4,E5,F5}{A4,C4,E5,F5,J5}
{A4,C4,E5,F5,J5,L5}
{A4}
{C4,B6,D6}{E5,F5,G6,B6,D6}
{F5,H6,G6,B6,D6,I7}
{J5,H6,G6,B6,D6,K7,I7}{L5,H6,G6,B6,D6,K7,I7}
{M5,H6,G6,B6,D6,K7,I7,N7}
A4C4
E5
F5J5
l5
m5m5
0
12
3
45
6
7
CloseOpennLn
nh gi gii thut Heuristic
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Slide 65
Admissibility Tnh chp nhn Mt gii thut Best first search vi hm nh gi
F(n) = G(n) + H(n) vi N : Trng thi bt k
G(n) : Ph tn i tnt bt u n nt n
H(n) : Ph tn c lng heuristic i tnt nn goal
c gi l gii thut A Mt gii thut tm kim c xem l admissible nu i
vi mt thbt kn lun dng path nghim tt nht
(nu c). Gii thut A*: L gii thut A vi hm heuristic H(n)lun
lun gi trthc i tn n goal.
Gii thut A* l admissible
nh gi gii thut Heuristic
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Slide 66
Monotonicity n iu Mt hm heuristic H(n)c gi lmonotone (n iu) nu:
ni, nj : nj l nt con chu ca ni ta cH(ni)-H(nj) ph tn tht i t ni n nj
nh gi heuristic ca ch l 0 : H(goal) = 0.
Gii thut A c hm H(n) monotone l gii thut A* vAdmissible
Informedness
Xt 2 hm heuristic H1(n) v H2(n) nu ta c H1(n)H2(n) vi mi trng thi n th H2(n)c cho linformed hn H1(n).
Heuristic trong tr chi i khng
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Slide 67
g g Gii thut minimax:
Hai u thtrong tr chi c gi l MIN v MAX.
Mi nt l c gi tr: 1 nu l MAX thng,
0 nu l MIN thng.
Minimax struyn cc gi trny ln cao dn trn th, qua cc
nt cha mktip theo cc lut sau: Nu trng thi cha ml MAX, gn cho n gi trln nht c trong cc trng
thi con.
Nu trng thi b, ml MIN, gn cho n gi trnhnht c trong cc trng
thi con.
C 4 Tm kim Heuristic
Hy p dng GT Minimax vo Tr Chi NIM
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Slide 68C 4 Tm kim Heuristic
Minimax vi su lp cnh
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Slide 69
Minimax i vi mt KGTT ginh.
Cc nt l c gn cc gi trheuristic
Cn gi trti cc nt trong l cc gi trnhn c da trngii thut Minimax
C 4 Tm kim Heuristic
Heuristic trong tr chi tic-tac-toe
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Slide 70
Hm Heuristic
: E(n) = M(n) O(n)Trong : M(n) l tng sng thng c thca tiO(n) l tng sng thng c thca i thE(n) l trsnh gi tng cng cho trng thi n
C 4 Tm kim Heuristic
Minimax 2 lp trong tic-tac-toe
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Slide 71
Trch tNilsson (1971).C 4 Tm kim Heuristic
Gii thut ct ta -
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Slide 72
Tm kim theo kiu depth-first.
Nt MAX c 1 gi tr (lun tng)
Nt MIN c 1 gi tr (lun gim) TK c thkt thc di bt k:
Nt MIN no c ca bt k nt cha MAX no.
Nt MAX no c ca bt k nt cha MIN no.
Gii thut ct ta - th hin mi quan h gia ccnt lp n v n+2, m ti ton b cy c gc ti
lp n+1 c th ct b.
C 4 Tm kim Heuristic
Ct ta
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Slide 73
S
A Z
MAX
MIN
= z
=
z
- cut
=
C 4 Tm kim Heuristic
Ct ta
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Slide 74
S
A Z
MIN
MAX
= z
=
z
- cut
=
C 4 Tm kim Heuristic
GT Ct Ta - p dng cho KGTT gi nh
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Slide 75C 4 Tm kim Heuristic
Cc nt khng c gi trlcc nt khng c duytqua
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TS. Nguyn nh ThunKhoa Cng nghThng tini hc Nha TrangEmail: thuanvinh122@gmail.com
Chng 4: Biu din v suy lun tri thc
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Slide 77
4.1. Mu tri thc, lnh vc v biu din tri thc.
4.2. Cc loi tri thc: c chia thnh 5 loi1. Tri thc th tc: m t cch thc gii quyt mt vn. Loi
tri thc nya ra gii php thc hin mt cng vic no. Cc dng tri thc th tc tiu biu thng l cc lut,chin lc, lch trnh v th tc.
2. Tri thc khai bo: cho bit mt vn c thy nh th no.Loi tri thc ny bao gm cc pht biun gin, di dngcc khngnh logic ng hoc sai. Tri thc khai bo cng cth l mt danh sch cc khngnh nhm m t y hnv i tng hay mt khi nim no.
4.2. Cc loi tri thc (tip)
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Slide 78
3. Siu tri thc: m t tri thc v tri thc. Loi tri thc ny gip lachn tri thc thch hp nht trong s cc tri thc khi gii quyt mt vn.Cc chuyn gia s dng tri thc ny iu chnh hiu qu gii quyt vn bng cch hng cc lp lun v min tri thcckh nng hn c.
4. Tri thc heuristic: m t cc "mo" dn dt tin trnh lp lun.Tri thc heuristic l tri thc khng bmm hon ton 100% chnh xc vkt qu gii quyt vn. Cc chuyn gia thng dng cc tri thc khoahc nh s kin, lut, sau chuyn chng thnh cc tri thc heuristic thun tin hn trong vic gii quyt mt s bi ton.
5. Tri thc c cu trc: m t tri thc theo cu trc. Loi tri thc nym t m hnh tng quan h thng theo quanim ca chuyn gia, baogm khi nim, khi nim con, v cci tng; din t chc nn g v milin h gia cc tri thc da theo cu trc xcnh.
V d: Hy phn loi cc tri thc sau
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Slide 79
1. Nha Trang l thnh ph p.
2. Bn Lan thchc sch.
3. Thut ton tm kim BFS, DFS4. Thut gii Greedy
5. Mt scch chiu tng trong vic chi ctng.
6. Hthng cc khi nim trong hnh hc.
7. Cch tp vit chp.
8. Tm tt quyn sch vTr tunhn to.
9. Chn loi cphiu mua cphiu.
4.3. CC KTHUT BIU DIN TRI THC
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Slide 80
4.3.1 B bai tng-Thuc tnh-Gi tr
4.3.2 Cc lut dn
4.3.3 Mng ng ngha4.3.4 Frames
4.3.5 Logic
4.3.1 B bai tng-Thuc tnh-Gi tr
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Slide 81
Mt s kin c th c dng xc nhn gi tr ca mt thuc tnh xcnh ca mt vii tng. V d, mnh "qu bng mu" xc nhn"" l gi tr thuc tnh "mu" cai tng "qu bng". Kiu s kin ny
c gi l b bai tng-Thuc tnh-Gi tr (O-A-V Object-Attribute-Value).
Hnh 2.1. Biu din tri thc theo bba O-A-V
4.3.1 B bai tng-Thuc tnh-Gi tr (tip)
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Slide 82
Trong cc s kin O-A-V, mti tng c th c nhiu thuc tnhvi cc kiu gi tr khc nhau. Hn na mt thuc tnh cng c thc mt hay nhiu gi tr. Chng c gi l cc s kin n tr
(single-valued) hoc a tr (multi-valued). iu ny cho php cch tri thc linhng trong vic biu din cc tri thc cn thit.
Cc s kin khng phi lc no cng bom lng hay sai vi chc chn hon ton. V th, khi xem xt cc s kin, ngi ta
cn s dng thm mt khi nim l tin cy. Phng php truynthng qun l thng tin khng chc chn l s dng nhn t chcchn CF (certainly factor). Khi nim ny bt u t h thngMYCIN (khong nm 1975), dng tr li cho cc thng tin suylun. Khi, trong s kin O-A-V s c thm mt gi tr xcnh tin cy ca n l CF.
4.3.2 Cc lut dn
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Slide 83
Lut l cu trc tri thc dng lin kt thng tin bit vi cc thng tin khc gipa ra cc suy lun,
kt lun t nhng thng tin bit. Trong h thng da trn cc lut, ngi ta thu thp cc
tri thc lnh vc trong mt tp v lu chng trong c
s tri thc ca h thng. H thng dng cc lut nycng vi cc thng tin trong b nh gii bi ton.Vic x l cc lut trong h thng da trn cc lutc qun l bng mt module gi l b suy din.
4.3.2 Cc lut dn(tip)
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Slide 84
Cc dng lut cbn: 7 dng1. Quan h:
IF Bnhin hngTHEN Xe s khng khingc
2. Li khuyn:
IF Xe khng khingcTHENi b
3. Hng dnIF Xe khng khingc AND H thng nhin liu tt
THEN Kimtrah thngin
4.3.2 Cc lut dn(tip)
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Slide 85
4. Chin lcIF Xe khng khingcTHEN u tin hy kim tra h thng nhin liu, sau kim tra hthngin
5. Din giiIFXen AND ting ginTHENng chotng bnh thng
6. ChnonIF St cao AND hay ho AND HngTHEN Vim hng
7. Thit kIFLnAND Da sng
THEN Nn chn Xe Spacy AND Chn mu sng
4.3.3 Mng ng ngha
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Slide 86
Mng ngngha l mt phng php biu din tri thc dng th trong nt biu din i tng v cung biu dinquan h gia cci tng.
Hnh 2.3. "Sl Chim" thhin trn mng ngngha
4.3.3 Mng ng ngha(tip)
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Slide 87
Hnh 4.4. Pht trin mng ngngha
V d: Gii bi ton tam gic tng qut
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Slide 88
C 22 yu tca tam gic. Nhvy c C322 -1 cch xy dng hayxc nh mt tam gic.Theo thng k, c khong 200 cng thc lin quan n cnh v gc 1tam gic.gii bi ton ny bng cng cmng ngngha, sdng khong200 nh cha cng thc v khong 22 nh cha cc yu tcatam gic. Mng ngngha cho bi ton ny c cu trc nhsau :
nh ca thbao gm hai loi :
nh cha cng thc (k hiu bng hnh chnht)nh cha yu tca tam gic (k hiu bng hnh trn)
Cung : chni tnh hnh trn n nh hnh chnht cho bit yuttam gic xut hin trong cng thc no
* L
u : trong mt cng th
c lin h
gi
a n yu t
ca tam gic, ta gi
nh rng nu bit gi trca n-1 yu t th s tnh c gi trca
yu tcn li. Chng hn nhtrong cng thc tng 3 gc ca tam gicbng 1800 th khi bit c hai gc, ta stnh c gc cn li.
V d: Gii bt tam gic tng qut (tt)
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Slide 89
B1 : Kch hot nhng nh hnh trn cho banu (nhng yu t c gi tr)B2 : Lp li bc sau cho n khi kch hot ctt c nhng nh ng vi nhng yu t cn tnhhoc khng th kch hot c bt k nh nona.
Nu mt nh hnh chnht c cung ni vi nnhhnh trn m n-1nh hnh trn c kch hotth kch hot nh hnh trn cn li (v tnh gi tr
nh cn li ny thng qua cng thc nh hnhchnht).
V d: Gii bt tam gic tng qut (tt)
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Slide 90
V d: "Cho hai gc , v chiu di cnh a ca tamgic. Tnh chiu di ng cao hC".
p
p=(a+b+c)/2
4.3.4 Frame
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Slide 91
Hnh 2.6. Cu trc frame
Hnh 2.7. Nhiu mc ca frame m tquan hphc tp hn
4.3.5 Logic
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Slide 92
1. Logic mnhIF Xe khng khingc (A)
AND Khong cch t nhn ch lm l xa (B)
THEN S tr gilm (C)
Lut trn c th biu din li nh sau:AB C
2. Logic v t Logic v t, cng ging nh logic mnh, dng cc k hiu
th hin tri thc. Nhng k hiun ygm hng s, v t, binv hm.
4.4 SUY DIN DLIU
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Slide 93
1. Modus ponens1. E1
2. E1 E2
3. E2
Nu c tin khc, c dng E2 E3 th E3c a vo danh sch.
2. Modus tollens1. E2
2. E1 E2
3. E1
4.5 Chng minh mnh
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Slide 94
Mt trong nhng vn kh quan trng ca logic mnh l chng minhtnh ng n ca php suy din (a b). y cng chnh l bi ton chng
minh thng gp trong ton hc. Vi hai php suy lun cbn ca logic mnh (Modus Ponens, Modus
Tollens) cng vi cc php bin i hnh thc, ta cng c thchng minhc php suy din. Tuy nhin, thao tc bin i hnh thc l rt kh ci tc trn my tnh. Thm ch iu ny cn kh khn vi ccon ngi!
Vi cng cmy tnh, c thcho rng ta sddng chng minh c mibi ton bng mt phng php bit l lp bng chn tr. Tuy vlthuyt, phng php lp bng chn trlun cho c kt qucui cngnhng phc tp ca phng php ny l qu ln, O(2n) vi n l sbin
mnh . Sau y chng ta snghin cu hai phng php chng minhmnh vi phc tp chc O(n).
4.5 Chng minh mnh
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Slide 95
Mt trong nhng vn kh quan trng ca logic mnh l chng minhtnh ng n ca php suy din (a b). y cng chnh l bi ton chng
minh thng gp trong ton hc. Vi hai php suy lun cbn ca logic mnh (Modus Ponens, Modus
Tollens) cng vi cc php bin i hnh thc, ta cng c thchng minhc php suy din. Tuy nhin, thao tc bin i hnh thc l rt kh ci tc trn my tnh. Thm ch iu ny cn kh khn vi ccon ngi!
Vi cng cmy tnh, c thcho rng ta sddng chng minh c mibi ton bng mt phng php bit l lp bng chn tr. Tuy vlthuyt, phng php lp bng chn trlun cho c kt qucui cngnhng phc tp ca phng php ny l qu ln, O(2n) vi n l sbin
mnh . Sau y chng ta snghin cu hai phng php chng minhmnh vi phc tp chc O(n).
4.5.1 Thut gii Vng Ho
B1 Ph bi l i i hi k l h d h
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Slide 96
B1 : Pht biu li githit v kt lun ca vn theo dng chun sau :GT1, GT2, ..., GTn KL1, KL2, ..., KLm
Trong cc GTi v KLi l cc mnh c xy dng tcc bin mnh v 3php ni cbn : , ,
B2 : Chuyn vcc GTi v KLi c dng phnh.V d:
p q, (r s), g, p r s, p p q, p r , p (r s), g, s
B3 : Nu GTi c php th thay thphp bng du ","Nu KLi c php th thay thphp bng du ","V d:
p q , r ( p s) q, s p, q, r, p s q, s
4.5.1 Thut gii Vng Ho
B4 N GT h th t h th h h i d
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Slide 97
B4 : Nu GTi c php th tch thnh hai dng con.Nu KLi c php th tch thnh hai dng con.V d:
p, p q q
p, p qv p, q q
B5 : Mt dng c chng minh nu tn ti chung mt mnh chai pha.V d:
p, q qc chng minhp, p q p p, qB6 :a) Nu mt dng khng cn php ni v php ni chai vv 2 v
khng c chung mt bin mnh th dng khng c chng minh.
b) Mt vn c chng minh nu tt cdng dn xut tdng chun ban uu c chng minh.V d: i) p ( p q) q
ii) (p q) ( p r) q r
4.5.2 Thut gii Robinson
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Slide 98
Thut gii ny hot ng da trn phng php chng minhphn chng v php hp gii Robinson.
Phng php chng minh phn chng: Chng minh php suy lun (a b) l ng (vi a l githit, b l kt
lun).
Phn chng : gisb sai suy ra b l ng.
Php hp gii Robinson:i) p ( p q) q
ii) (p q) ( p r) q r
Bi ton c chng minh nu a ng v b ng sinh ra mt muthun.
4.5.2 Thut gii Robinson (tip)
1 h bi l i i hi k l d i d h
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Slide 99
B1 : Pht biu li githit v kt lun ca vn di dng chunnhsau :
GT1, GT2, ..., GTn KL1, KL2, ..., KLm
Trong : GTi v KLjc xy dng tcc bin mnh v ccphp ton : , , B2 : Nu GTi c php th thay bng du ","
Nu KLi c php th thay bng du ","
B3 : Bin i dng chun B1 vthnh danh sch mnh nhsau :{ GT1, GT2, ..., GTn , KL1, KL2, ..., KLm }
B4 : Nu trong danh sch mnh bc 2 c 2 mnh i ngunhau th bi ton c chng minh. Ngc li th chuyn sangB5. (a v a gi l hai mnh i ngu nhau)
4.5.2 Thut gii Robinson (tip)
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Slide 100
B6 : p dng php hp gii
i) p ( p q) q
ii) (p q) ( p r) q rB7 : Nu khng xy dng c thm mt mnh mi no v
trong danh sch mnh khng c 2 mnh no i ngunhau th vn khng c chng minh.
V d: Chng minh rng( p q) ( q r) ( r s) ( u s) p u
Chng 5 My hc
5 1 M U
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Slide 101
5.1 MU Cc chng trc tho lun v biu din v suy lun tri
thc. Trong trng hp ny gi nh c sn tri thc v c t h
biu din tng minh tri thc. Tuy vy trong nhiu tinh hung, s khng c sn tri thc nh:
K s tri thc cn thu nhn tri thc t chuyn gia lnh vc. Cn bit cc lut m t lnh vc c th.
Bi ton khngc biu din tng minh theo lut, s kin hay ccquan h.
C hai tip cn c h o h thng hc: Hc t k hiu: bao gm vic hnh thc ha, sa cha cc lut tng
minh, s kin v cc quan h.
Hc t d liu s: c p dng cho nhng h thngc m hnh didng s lin quann cc k thut nhm tiu cc tham s. Hc theodng s bao gm mng Neural nhn to, thut gii di truyn, bi ton tiu truyn thng. Cc k thut hc theo s khng to ra CSTT tngminh.
5.2 CC HNH THC HC
1 Hc vt: H tip nhn cc khng nh ca cc quyt nh
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Slide 102
1. Hc vt: H tip nhn cc khngnh ca cc quytnhng. Khi h to r a mt quytnh khngng, h s a racc lut hay quan h ng m h s dng. Hnh thc hc
vt nhm cho php chuyn gia cung cp tri thc theo kiutng tc.
2. Hc bng cch ch dn: Thay va r a mt lut c th cnp dng vo tnh hung cho trc, h thng s c cungcp bng cc ch dn tng qut. V d: "gas hu nh b thotra t van thay v thot ra t ng dn". H thng phi t mnh ra cch bini t tru tngn cc lut kh dng.
3. Hc bng qui np: H thngc cung cp mt tp cc v d v kt lunc rt ra t tng v d. H lin tc lc cclut v quan h nhm x l tn g v d mi.
5.2 CC HNH THC HC (Tip)
4. Hc bng tng t: H thngc cung cppngng cho cc tc
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Slide103
g g g g p p g gv tng t nhng khng ging nhau. H thng cn lm thchngpng trc nhm to ra mt lut mi c kh nng p dng cho tnhhung mi.
5. Hc da trn gii thch: H thng phn tch tp cc li gii v d (v ktqu) nhmnnh kh nngng hoc sai v to ra cc gii thch dng hng dn cch gii bi ton trong tng lai.
6. Hc da trn tnh hung: Bt k tnh hung noc h thng lp lunuc lu tr cng vi kt qu cho dng hay sai. Khi gp tnh
hng mi, h thng s lm thch nghi hnh vi lu tr vi tnh hungmi.
7. Khm ph hay hc khng gim st: Thay v c mc tiu tng minh, hkhm ph lin tc tm kim cc mu v quan h trong d liu nhp. Ccv d v hc khng gim st bao gm gom cm d liu, hc nhndng ccc tnh cbn nh cnh t ccimnh.
V d v CC HNH THC HC
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Slide 104
V d:
- H MYCIN- Mng Neural nhn to
- Thut ton hc Quinland
- Bi ton nhn dng- My chi ccar, ctng
5.3 THUT GII Quinlan
L thut ton hc theo quy np dng lut a mc tiu
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Slide 105
- L thut ton hc theo quy np dng lut, a mc tiu.
- Do Quinlan a r a nm 1979.
- tng: Chn thuc tnh quan trng nht to cyquytnh.
- Thuc tnh quan trng nht l thuc tnh phn loi
Bng quan st thnh cc bng con sao cho t mi bngcon ny d phn tch tm quy lut chung.
5.3.1 THUT GII A. Quinlan
ConclusionFamilyNationalitySizeSTT
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Slide 106
ASingleGermanLarge3
BMarriedGermanSmall8
BMarriedItalianLarge7
BSingleItalianLarge6
BMarriedGermanLarge5
BSingleItalianSmall4
ASingleFrenchLarge2
ASingleGermanSmall1
yy
Vi mi thuc tnh ca bng quan st:
Xt vector V: c s chiu bng s phn loi
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Slide 107
V(Size=Small) = (ASmall, BSmall)
ASmall=S quan st A c Size l Small / Tng s quan st c Size=Small
BSmall= S quan st B c Size l Small / Tng s quan st c Size=SmallV(Size=Small) = (1/3 , 2/3)
V(Size=Large) = (2/5 , 3/5)
Vi thuc tnh NationalityV(Nat = German)= (2/4 , 2/4)
V(Nat = French) = (1 , 0)V(Nat = Italian) = (0 , 1)
Thuc tnh Family:V(Family=Single) = (3/5 ,2/5)
V(Family = Married)
= (0, 1)
Vi mi thuc tnh ca bng quan st:
Ch cn xt German ConclusionFamilySizeSTT
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Slide 108
Thuc tnh Size:V(Size=Small) = (1/2 , 1/2)V(Size=Large) = (1/2 , 1/2)
Thuc tnh Family:V(Family=Single) = (1, 0)V(Family=Married) = (0,1)
ConclusionFamilySizeSTT
BMarriedSmall4
BMarriedLarge3
ASingleLarge2
ASingleSmall1
Nationality
Italian French German
Single Married
Vi mi thuc tnh ca bng quan st(tip)
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Slide 109
Nationality
Italian French German
Single Married
Rule 1: If (Nationality IS Italian) then (Conclusion IS B)
Rule 2: If (Nationality IS French) then (Conclusion IS A)
Rule 3: If (Nationality IS German) AND (Family IS Single)
then (Conclusion IS A)
Rule 4: If (Nationality IS German) AND (Family IS Married)then (Conclusion IS B)
5.3.2 Thut gii Hc theo btnh
ProfitTypeCompetitionAgeStt
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Slide 110
DownHardwareYesOld10
DownHardwareYesMidle9
UpSoftwareYesNew8
UpSoftwareNoMidle7
UpSoftwareNoNew6
UpHardwareNoNew5
DownHardwareNoOld4
UpHardwareNoMidle3
DownSoftwareYesMidle2
DownSoftwareNoOld1
yppg
Hc theo btnh(tip)
b h X k
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Slide 111
btnh ca X:
Tnh Entropy cho mi thuc tnh v chn thuc tnh c Entropynh nht.
=
=k
1i2log-)( ii ppXE
=+=
==
==
=
=
=
=
8752.0811.0*4.0918.0*6.0)/(
811.043log
43-
41log
41-)/(
918.06
2log
6
2-
6
4log
6
4-)/(
),(log),(-)/(
22
22
k
1i
2
nCompetitioCE
CE
CE
acpacpACE
YesnCompetitio
NonCompetitio
iiii
Hc theo btnh(tip)
Tng t:
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Slide 112
E(C/Age) = 0.4
E(C/Type) = 1
Age cho nhiu thng tinnht
ProfitTypeCompetitionSTT
DownHardwareYes4
UpSoftwareNo3
UpHardwareNo2
DownSoftwareYes1
Age
Old Milde New
Down Competition Up
No Yes
Up Down
Hc theo btnh(tip)
Age
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Slide 113
Age
Old Milde New
Down Competition Up
No Yes
Up Down
Rule 1: If (Age IS Old) then (Profit IS Down)
Rule 2: If (Age IS New) then (Profit IS Up)
Rule 3: If (Age IS Midle) And (Competition IS No)
then (Profit IS Up)Rule 4: If (Age IS Midle) And (Competition IS Yes)
then (Profit IS Down)
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