antifragility = elasticity + resilience + machine learning. models and algorithms for open system...
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Presentation for the ANTIFRAGILE 2014 workshop, https://sites.google.com/site/resilience2antifragile/ Abstract: We introduce a model of the fidelity of open systems—fidelity being interpreted here as the compliance between corresponding figures of interest in two separate but communicating domains. A special case of fidelity is given by real-timeliness and synchrony, in which the figure of interest is the physical and the system’s notion of time. Our model covers two orthogonal aspects of fidelity, the first one focusing on a system’s steady state and the second one capturing that system’s dynamic and behavioral characteristics. We discuss how the two aspects correspond respectively to elasticity and resilience and we highlight each aspect’s qualities and limitations. Finally we sketch the elements of a new model coupling both of the first model’s aspects and complementing them with machine learning. Finally, a conjecture is put forward that the new model may represent a first step towards compositional criteria for antifragile systems.TRANSCRIPT
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