A.8.6 Enabling monotonic CLP(B)
In the default execution mode, CLP(B) constraints are not monotonic. This means that adding constraints can yield new solutions. For example:
?- sat(X=:=1), X = 1+0. false. ?- X = 1+0, sat(X=:=1), X = 1+0. X = 1+0.
This behaviour is highly problematic from a logical point of view, and it may render declarative debugging techniques inapplicable.
Set the flag clpb_monotonic to true
to make
CLP(B) monotonic. If this mode is enabled, then you must wrap
CLP(B) variables with the functor v/1. For
example:
?- set_prolog_flag(clpb_monotonic, true). true. ?- sat(v(X)=:=1#1). X = 0.