4.1 The Set-up

4.1.3 Communication and Imitation

Each agent can communicate with any of the others once a week, immediately before they all decide whether to go to the bar or not. The communication is determined by the evaluation of the talk expression and is usually either `true' or `false'. The presence of a quoting operator (quote) in the formal language of the talk expression allows subtrees of the talk expression to be the content of the message. If a quote primitive is reached in the evaluation of the talk expression then the contents of the subtree are passed down verbatim rather than evaluated. If a quoted tree is returned as the result of an evaluation of the talk expression then this is the message that is communicated.

The content of the messages can be used by agents by way of the saidBy and saidByLast primitives in the action and talk expressions. If `listening' is enabled then other agents can use the message in its evaluation of its expressions - if the message is just composed of a boolean value then the saidBy primitive is just evaluated as this value, but if it is a more complex expression (as a result of a quote primitive in the sending agents talk expression) then the whole expression will be substituted instead of the saidBy (or saidByLast) primitive and evaluated as such. The agent can use the output of its own messages by use of other primitives (IPredictedLastWeek and ISaidYesterDay).

If `imitation' is enabled then other agents can introduce any message (which is not a mere boolean value) into their own (action) gene pool, this would correspond to agents taking the message as a suggestion for an expression to determine their own action. In subsequent weeks this expression can be crossed with other expressions in its population of strategies.

Runs of the model with and without `listening' enabled are intended to contrast the effect of the communication on the embedding, and runs with and without `imitation' to investigate the effect of sharing the pool of strategies explicitly. In all runs agents can follow each others actions by reference (i.e. through the use of wentLastWeek) - this differs from `imitation' in that no transference of the content of the strategies takes place, only the results.

Capturing Social Embeddedness: a constructivist approach - Bruce Edmonds - 30 OCT 98

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