Open Reflective Agents Sylvain Giroux LICEF, Télé-Université 1001 Sherbrooke est C.P. 5250, succ. C Montréal, P.Q. Canada H2X 3M4 sgiroux@teluq.uquebec.ca
PLAN 1- Motivation and approach 2- Adaptation 1- The viewpoint of Gregory Bateson 2- On mechanisms for adaptation 3- From real world towards software agents 3- ReActalk 1- The viewpoint embodied within ReActalk 2- An Actor Internal Behavior 3- A Generic Factory 4- Adaptive mechanisms 1- Conscious acquisition of somatic abilities 2- Removing obsolete somatic abilities and metalevels 5- Conclusion 1
Motivations The Problem • Real systems are open ---> Agents ought to be open. • When an agent is intended for open multi-agent systems, its designer can -> neither exactly predict behaviour of other agents -> nor rely on some sort of Esperanto. • Stating the problem differently, interoperability is an issue ensuing from openness. Issues raised by openness and directions towards solutions #1 how agents can interact despite of different behaviours and models of computation ? agents should at least adhere to a common ontology #2 how could agents live and act in evolving and unpredictable worlds? they must have adaptive mechanisms Long-term benefits expected from open agents • Agents will learn to interact together, so designers and users interventions are less likely to be needed. • Open agents increase the robustness of both agents and multi-agent systems. • Agents and multi-agent systems will become easier to design and maintain; for instance, to build up a system, one just has to hire pre-built open agents. 2
Our Approach 1- Definition of a minimal ontology that could set the guidelines for open adaptive agents. 2- ReActalk as a reflective platform for the study of adaptation in open multi-agent systems. ReActalk helps • viewing information systems as open agents • viewing agents as open information (eco)systems • viewing interoperabilty as an adaptive process 3- Application of ReActalk architecture and adaptive mechanisms a) to solve interoperability issues arising around Actalk actors b) to build an open agenda system c) EpiTalk, epiphyte information systems applied to advisors d) SMAVOR, volcanoes models and simulation 3
Adaptation The viewpoint of Gregory Bateson • As a starting point, we adopted the viewpoint of Bateson on adaptation “adaptation : A feature of an organism whereby it seemingly fits better into its environment and way of life. The process of achieving t hat fit. ” [Bateson, Mind and Nature] • Remarks 1- Bateson underlines the relation that links together a living being and its environment a living being and its evolution cannot really be understood unless the living being is understood as part of a larger system 2- There are merely two ways to adapt ---> to self-modify example: speeding up one's heart rate at a high altitude ---> to modify its environment example: agriculture 4
On Mechanisms for Adaptation • to assemble and modify dynamically models of computation in respect to interactions an agent has with its environment -> conscious adaptation analogy: learning from social intercourse purpose: - to solve interoperability issues requirements: - to detect situations calling for adaptive modifications - to trigger adaptive modifications - to carry out adaptive modifications incorporating new abilities -> unconscious adaptation analogy: forgetting purposes: - not to overweight needlessly the agent internal processes - to keep the sole abilities relevant in the current ecosystem of the agent requirements: - to decide between obsolete abilities and helpful ones - to trigger adaptive modifications - to remove obsolete abilities 5
From Real World towards Software Agents but Sm allt alk - 8 0 ob ject s class <=> umbilical cord - modelling passive and sequent ial object s - programming environment but Open Syst ems act ors an act or does not consider (Carl Hewit t ) it is embedded int o a syst em - concurrency - asynchronous - decent ralized cont rol Dist r ib ut e d but agent s A r t i f ic ia l laws regulat ing t he world Int elligence are kept occult - from isolat ion t owards a syst emic approach but Art if icial Life env ironment art ificial beings usually lack - how global macro-behaviors mechanism enabling t hem do emerge out of local micro-behaviors t o modify t heir behavior - ecosyst em reificat ion dynamic and t emporary Re f le ct ion adapt at ion modificat ions of oneself - t o reason and act upon oneself on a individual basis Re A c t a lk 6
The Viewpoint Embodied within ReActalk • the world is made of actors that are active and concurrent; an actor is reflective and thus can reason or act upon its own behavior; • • an actor can always be decomposed into an organisation of actors which acts as its reflective representation; • an agent is an actor, member of an organisation; • an ecosystem is reified as an organisation, that is through the vantage point of its members and relations amongst members; • interactions are performed through message passing. 7
An Actor Internal Adaptive Behavior Basis : Actalk - small kernel - already available extensions towards actor models of computation - to take advantage of Smalltalk-80 programming environment Actalk was developed by Jean-Pierre Briot Objective : to render explicit the computational behavior of an actor -> in order to modify it dynamically Observation : an actor behavior is driven by messages (external stimuli) Analogy : computational behavior <----> factory messages <----> pieces actors / agents <----> workers How : by isolating each step of the processing of a message 8
A Generic Factory Organization agents = {ArrivalManager, ... } relations ={ (ArrivalManager, Receptionist, CommunicationProtocol), ... } d e n o t a t i o n ScriptManager MailBoxRetreiver MailboxOrganizer Receptionist after execution execution of script before execution ExecutionManager ArrivalManager MetaActor meta (as an agent) arrivalOf: aMessage d e n o ta t i o n Organization ReflectiveActor meta (as an individual) meta (as an agent) m a i l b o x aMessage b e h a v i o r ReflectiveActorBehavior a s e l f 9
On Mechanisms for Adaptation • to assemble and modify dynamically models of computation in respect to interactions an agent has with its environment -> conscious adaptation analogy: learning from social intercourse purpose: - to solve interoperability issues requirements: - to detect situations calling for adaptive modifications - to trigger adaptive modifications - to carry out adaptive modifications incorporating new abilities -> unconscious adaptation analogy: forgetting purposes: - not to overweight needlessly the agent internal processes - to keep the sole abilities relevant to the agent current ecosystem requirements: - to decide between obsolete abilities and helpful ones - to trigger adaptive modifications - to remove obsolete abilities 10
Conscious Acquisition of Somatic Abilities rest ructuration t hrough hy br idiz at ion 11
On Mechanisms for Adaptation • to assemble and modify dynamically models of computation in respect to interactions an agent has with its environment -> conscious adaptation analogy: learning from social intercourse purpose: - to solve interoperability issues requirements: - to detect situations calling for adaptive modifications - to trigger adaptive modifications - to carry out adaptive modifications incorporating new abilities -> unconscious adaptation analogy: forgetting purposes: - not to overweight needlessly the agent internal processes - to keep the sole abilities relevant to the agent current ecosystem requirements: - to decide between obsolete abilities and helpful ones - to trigger adaptive modifications - to remove obsolete abilities 12
Removing Obsolete Somatic Abilities and Metalevels surveillance on the met alevel rest ruct urat ion organizat ion t hrough reif icat io n unhy bridiz at ion - behavior reif icat ion behavior reificat ion def ault hyb rid model of comput at ion model of comput at ion r e v e r se (1) (2) (3) 13
Conclusion • In order to adapt, an agent modifies itself at the mercy of interactions within its ecosystem. These interactions trigger its adaptive mechanisms. • Organizational reflection, thanks to adaptive mechanisms, allows to smoothly assemble on the fly multi-agent systems and to intertwine agent specifications, easing programs cooperation and consequently the programmer tasks. • Two identical agents inserted into different ecosystems can experience divergent evolution and may later exhibit distinct behaviors. Reflection frees an agent from its genetic behavior (defined by its class) and gives it the keys to somatic evolution. 14
Esquisse d’une ontologie A1 le monde réel est composé d’objets; A2 les systèmes du monde réel sont fondamentalement ouverts; les systèmes réels sont reliés au monde externe et communiquent avec lui; A3 le monde réel évolue en parallèle; A4 toute entité appartient à un environnement elle doit être comprise en relation avec cet environnement; A5 toute entité a besoin de s’adapter à des situations nouvelles. par conséquent, elle doit pouvoir soit se modifier dynamiquement, soit modifier dynamiquement modifier son environnement 15
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