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+Goal infers +Language

Succeeds if Goal succeeds. Computes the most specific generalization of all the solutions of the Goal according to the approximation Language and delays if Goal has several non comparable solutions.
+Goal
Callable Term.
+Language
One of the terms most, unique, consistent, fd, range or ac

Description

Used to do generalized propagation over Goal.

With the language 'most', Goal is bound to the most specific generalization of all its solutions. This generalisation will depend what solvers are loaded - (fd, range or both). If one of the solutions is not a variant of this answer, the goal is delayed until one of its variables is bound. Note that the Goal may have an infinity of solutions.

Using other languages, an approximation of this most specific generalization can be computed. With the 'unique' language, infers/2 instantiates the Goal only if it has a unique solution (or the first solution of Goal subsumes all the others). With the 'consistent' language, infers/2 does not bind the Goal but only checks if Goal has at least one solution. The languages 'fd' and 'range' extract the most specific generalisation expresssible using finite domains and ranges respectively. The language 'ac' implements generalised arc consistency on the table produced by computing all the (finitely) many solutions to the goal in advance.

Fail Conditions

Fails if Goal has no solution.

Resatisfiable

No.

Exceptions

(4) instantiation fault
Goal or Language is not instantiated.
(6) out of range
Language is not a correct language.
(68) calling an undefined procedure
Goal is an undefined procedure.

Examples

    Success:
	[eclipse]: member(X, [f(1), f(2)]) infers most.
        X = f(_g1)
        Delayed goals:
        member(f(_g1), [f(1), f(2)]) infers most
        yes.
	[eclipse]: [user].
	and(0, 0, 0).
        and(0, 1, 0).
	and(1, 0, 0).
	and(1, 1, 1).
	user       compiled traceable 528 bytes in 0.00 seconds
	yes.
	[eclipse]: and(0, X, Y).
	X = X
	Y = 0     More? (;)          % Prolog: two solutions
	X = 0
	Y = 0
	yes.
	[eclipse]: and(0, X, Y) infers most.
	X = X
	Y = 0
	yes.                         % Prolog + infers: one solution
	[eclipse]: [user].
	greater_than(succ(X), X).
	greater_than(succ(X), Y) :- greater_than(X, Y).
	user       compiled traceable 268 bytes in 0.00 seconds
	yes.
	[eclipse]: greater_than(X, zero).
	X = succ(zero)     More? (;) % Prolog: infinity of solutions
	...
	[eclipse]: greater_than(X, zero) infers most.
	X = succ(_g2)
	Delayed goals:
	    infers(greater_than(succ(_g2), zero), most, eclipse)
	yes.
        [eclipse]: lib(fd).
        ...
        [eclipse]: member(X, [f(1), f(2)]) infers most.
	X = f(_g3[1, 2])
	yes.
    Fail:
	[eclipse]: member(1, [2, 3]) infers consistent.
	no (more) solution.
    Error:
	Goal infers most. % Error 4
	true infers true.  % Error 6

See Also