Function

Summary

Return the first match of a backward chaining goal.

Signature

any pattern-to-instantiate goal-to-prove => result, successp

Arguments

pattern-to-instantiate

A list or symbol.

goal-to-prove

Any backward chaining goal.

Values

result

nil or a value matching pattern-to-instantiate

successp

A boolean.

Description

The backward chaining inference engine is started to look for any set of bindings which satisfy goal-to-prove. Using those bindings, pattern-to-instantiate is instantiated and returned.

Two values are returned. The second value indicates with t that a proof was found, or with nil that no proof exists. In the former case, the first value is the instantiated version of pattern-to-instantiate, in the latter case, the first value is nil.

Any subgoals that match the object base will only find objects from the current inferencing state.

Examples

returns (1 IS IN (1 2 3)), T

returns (#<TRUCK TRUCK5> IS A TRUCK), T

See also

findall