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Plans in JaKtA

Plans in JaKtA define how an agent achieves its goals by executing a sequence of actions. Plans react to events, such as new goals to achieve or changes in beliefs.

Understanding Plans​

Inheriting the successful model of Jason, in JaKtA, plans are composed of a triggering event deciding whether the plan is relevant, an optional context restricting its applicability, and a body listing the operations to be performed whenever the plan is executed.

The triggering event can be a goal/belief invocation/addition (+) or failure/deletion (-), in the form:

[+|-] <triggering event> onlyIf {<context>} then {<body>}.

We inherit from Jason the usage of a prefix unary + to indicate invocation or additions, and a prefix unary - to indicate failures or deletions.

If a logical expression is present in the context block (prefixed by onlyIf), it is then used to vet the relevant plan. The condition therein expressed should be a logic formula to be tested against the belief base via logic resolution. Finally, if the plan is selected for execution, the sequence of operations and actions contained in its body (prefixed by then) is performed by the agent. There, actions may consist of edits (additions or deletions) to the belief base, as well as additions of further achievement or test goals, or invocations of external or internal actions (see next paragraphs).

Defining Plans in JaKtA DSL​

In JaKtA, plans are declared within an agent’s configuration, specifying what to do when a goal is pursued.

agent("Robot") {            
    plans {
        +/-achieve("goal"(X)) onlyIf { "guard"(X) } then { 
            achieve("goal"(X))
            test("goal"(Y))
            spawn("goal"(Z))
            +/-"belief"(A)
            update("belief"(C))
            execute("action"(X, Y, Z)) 
        }
        +/-test("goal"(Y)) onlyIf { "guard"(Y) } 
            then { /*...*/ }
        +/-"belief"(Z) onlyIf { "guard"(Z) } 
            then { /*...*/ }
    }
}