antifragility = elasticity + resilience + machine learning. models and algorithms for open system...

Vincenzo De Florio

MOSAIC group, Universiteit Antwerpen & iMinds

vincenzo.deflorio@uantwerpen.be

What is computational antifragility?

Is it different from, e.g.,

dependability, resilience, elasticity,

robustness, safety?

WHY?

A system's ability to

preserve its identity

through an active behavior

Aristotle’s entelechy

“being at work (active behavior)

staying the same” (preserving identity) [Sachs, Aristotle’s Physics: A Guided Study. 1995]

What do we mean by Identity?

Voice-over-IP system; call b/w two

endpoints

The identity of the system is

the fact that the system works!

Communication is possible b/w the

endpoints

the experienced QUALITY of the

communication matches the

expectations of the two endpoints!

Throughout the call!

If the experienced quality of the

communication matches the

expected quality,

the system is resilient

If the system is not able to

compensate for disturbances and

the qualities drift away,

the system is not resilient.

Thus resilience calls for a property: fidelity

Fidelity: quality of representation & control between a reference domain and an execution domain

Physical world Cyberworld

Fidelity must preserve concepts! Delay, Echo, Jitter, Latency…

Time!

Fidelity: A property of open systems.

Leibniz!

Open system: systems that “interact

with other systems outside of

themselves” [Heylighen ‘98]

The interaction may involve n

aspects, corresponding to n context

variables

Luminosity; jitter; sound; time…

n-open systems.

One such aspect can be time

time-open systems

aka Real-time systems!

Systems that have a “social notion” of

time

Systems that base their action on the

accuracy of an internal representation

of time.

Quality = a measure of the drift

between the internal representation and

the measured context variable.

RTS: cybertime physical time

The fidelity of a time-open system

depends on the quality of RTS

1. Perfect correspondence: reference

point

No drift

2. Strong correspondence: hard RT

Known and fixed drifts.

3. Statistical correspondence: soft RT

Known average / stdev values

Active behaviors

4. Practical correspondence: best-

effort

“Usually drifts are tolerated by the

users”

Passive behaviors

5. No guarantee: as-is.

[RT]1 … [RT]5 : Five classes

(just an example!)

Resilience =

perform intended function

(“being at work”)

Staying in the same class

(“staying the same”)

Being at work: different ways to do so!

Behavior! “any change of an entity

with respect to its surroundings”

[RWB’43]

Here: Any change an entity enacts

in order to sustain its system

identity.

Different classes of behaviors.

Passive: inert systems

As-is, best-effort !

No guarantees!

Purposeful: servo-mechanisms

Guarantees through elasticity / fault

masking

Redundancy is predefined and statically

defined as a result of Worst-case

Analyses

Sitting ducks!

Teleologic / extrapolatory: action is

f (goal) / f (predicted goal)

Resilience!

Boulding’s “Animals”: models of the

“self” and of the “world”

Auto-predictive: learning systems

the action of the environment and of

the system leaves a footprint in the

system

System “learns” by ranking strategies

with obtained results (cf. EGT…).

Auto-predictive systems:

open to their own system-

environment fit!

SEF-open systems!

wisdom is developed as a result of the

match between strategy and obtained

results.

Elasticity + Resilience + Machine

Learning!

Use elasticity if identity is not

jeopardized

Requires: monitoring the drift!

If identity is jeopardized:

Use resilience (both individual and

collective); and learn!

Measure effectiveness of current

solutions

Rank current solution with respect to

past ones

Derive and persist conclusions

Update resilience models accordingly.

Computational antifragility does

make sense

It is an urgent need! (cf. keynote

speech & today’s papers!)

A lot needs to be done yet PANEL

How do we move from ideas to an

engineering practice?

Antifragility vs autonomic behaviors?

Shall we begin??

Thanks for your

attention!

Autoresilience

Quality indicators

Perception &

apperception

System-Environ-

ment Fit