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Summary

The action of agreeing to perform some action, possibly in the future.

Content

A tuple, consisting of an action expression denoting the action to be done, and a proposition giving the conditions of the agreement.

Description

Agree is a general-purpose agreement to a previously submitted request act (see [FIPA00056]) to perform some action. The agent sending the agreement informs the receiver that it does intend to perform the action, but not until the given precondition is true.

The proposition given as part of the agree act indicates the qualifiers, if any, that the agent is attaching to the agreement. This might be used, for example, to inform the receiver when the agent will execute the action that it is agreeing to perform.

Pragmatic note: the precondition on the action being agreed to can include the perlocutionary effect of some other CA, such as an inform act (see [FIPA00046]). When the recipient of the agreement (e.g. a contract manager) wants the agreed action to be performed, it should then bring about the precondition by performing the necessary CA. This mechanism can be used to ensure that the contractor defers performing the action until the manager is ready for the action to be done.

Formal Model

<i, agree(j, <i, act>, f))>º
  <i, inform(j, I_i Done(<i, act>, f))>
    FP: B_i aÙØB_i (Bif_j aÚ Uif_j a)
    RE: B_j a

Where:

  a = I_i Done(<i, act>, f)

Note that the formal difference between the semantics of agree and accept-proposal (see [FIPA00039]) rests on which agent is performing the action.

Example

Agent i (a job-shop scheduler) requests j (a robot) to deliver a box to a certain location. J answers that it agrees to the request but it has low priority.

(request
  :sender i
  :receiver j
  :content

    (action j (deliver box017 (location 12 19)))
  :protocol FIPA-Request
  :reply-with order567)

(agree
  :sender j
  :receiver i
  :content

    ((action j (deliver box017 (location 12 19))

      (priority order567 low)))
  :in-reply-to order567
  :protocol FIPA-Request)