Stigmergy: a fundamental paradigm for digital ecosystems?

Transcription

1 Stigmergy: a fundamental paradigm for digital ecosystems? Francis Heylighen Evolution, Complexity and Cognition group Vrije Universiteit Brussel 1

2 Digital Ecosystem Complex, self-organizing system Agents: businesses, organizations, individuals... exchanging information, services, goods co-evolving, mutually adapting Supported by shared ICT infrastructure digital environment or medium How to design an efficient digital medium for DE? 2

3 The concept of stigmergy Introduced by the entomologist Grassé in the 1950 s to explain activity of social insects such as termites, ants and wasps. apparently complex and coordinated yet individuals very dumb effective self-organization Now popular in Multi-Agent Systems (robots, simulations) 3

4 Basic principle Greek etymology stigma = stimulus, sign ergon = work work performed by an agent leaves a trace in the environment or medium perceiving the trace stimulates another agent to perform further work thus extending or elaborating previous work 4

5 Mechanism Perceived condition function as stimulus, action as response or work Feedback loop: condition action new condition new action... action changes medium change is perceived new condition each action corrects or builds upon the previous one 5

6 Example: termite hill construction first termites drop mud randomly later termite tend to drop mud on already present mud positive feedback: mud more mud the mud heap grows into a column columns tend to grow towards each other cathedral-like structure with arches 6

7 Ant trail networks Ants coming back from food source leave pheromone trace Ants searching for food preferentially follow pheromone trail preference increases with strength of trail Strong trails get reinforced as more ants use them Trails to exhausted food sources evaporate Result: network of trails connecting food sources in most efficient way external memory of food locations adapts constantly to new circumstances 7

8 Ant trail networks 8

9 Quantitative qualitative Quantitative stigmergy: trace changes probability or amount of further action e.g. amount of mud for termite, or of pheromone for ant Qualitative stigmergy: trace elicits new type of action e.g. Wikipedia 9

10 Collaboration in Wikipedia Person A writes text on topic X action Person B reads text stimulus, perception Person B thinks text can be improved Person B then adds or corrects text qualitatively new action Positive feedback: more edits better text more readers more edits... 10

11 O u r p r e s e n t networked society o p p o r t u n i t i e s, constraints, risks O u r p r e s e n t networked society O u r po rp ep so er tn ut n i t i e s, networked constraints, society risks o p p o r t u n i t i e s, constraints, risks O u r p r e s e n t networked society o p p o r t u n i t i e s, constraints, risks O u r p r e s e n t networked society o p p o r t u n i t i e s, constraints, risks O u r p r e s e n t networked society o p p o r t u n i t i e s, constraints, risks Wikipedia O u r p r e s e n t networked society o p p o r t u n i t i e s, constraints, risks O u r p r e s e n t networked society o p p o r t u n i t i e s, constraints, risks O u r p r e s e n t networked society o p p o r t u n i t i e s, constraints, risks O u r p r e s e n t networked society o p p o r t u n i t i e s, constraints, risks O u r p r e s e n t networked society o p p o r t u n i t i e s, constraints, risks 11

12 Medium as shared memory Actions leave signs in medium information is reliably stored information is easily retrieved Signs function as external memory accessible by all agents shared between all agents Topological differentiation of space different regions accumulate different types of signs 12

13 Coordination Coordinating different actions requires knowing which action is to be done when by whom This is difficult for agents with limited memory especially when the action pattern is very complex External memory overcomes this problem This makes possible a highly organized and intelligent pattern of activity performed by agents with very incomplete knowledge 13

14 Advantages of stigmergy No need for: simultaneous presence of agents interaction can be asynchronous direct communication between agents agents can be anonymous, unaware of each other planning or prediction of activities agents can be ignorant of what happens next precise sequencing of actions (workflow) next actions are triggered by previous ones 14

15 No need for: imposed division of labour E.g. collaboratively developing Wikipedia page or opensource application People tend to check pages/modules they are interested in and therefore tend to have some expertise in Non-experts are not inclined to change page/module tasks are preferentially performed by the most expert since they are most stimulated to act and can do the job with least effort 15

16 Open Knowledge Ecosystems Agents use and produce knowledge knowledge publicly available in shared external memory e.g. Wikipedia Everybody can use the knowledge freely Everybody can contribute freely 16

17 Business Ecosystems Agents (SMEs) supply goods or services (output) but require (demand) resources (input) Agent Agents process input into output Problem: match input of one agent to output of other agent Input Output 17

18 DBE as network E c l h k j f e I a i O d g b S 18

19 Virtual Markets Demand and Supply posted on public medium need A (qualitative), am willing to pay X (quantitative) can supply B (qual.), for the price Y (quant.) Agents browse through medium to find supply that best matches their demand, or vice-versa Law of supply and demand : prices should automatically adjust to make supply match demand 19

20 Required technologies Shared digital medium: open, non-proprietary Ontology for characterizing available demand/ supply offers (qualitative) Bidding algorithms to increase/decrease price when no reaction is forthcoming (quantitative) Feedback for rewarding qualitatively best offers Software agents for finding most attractive demand/supply opportunities given knowledge of own preferences/expertise 20