(no dependencies on other entities)
Sets a constraint that is true iff the two terms are different.
Delays the execution of a goal until a variable is bound.
Unifies Goal with the goal delayed by Variable. When no goals are frozen on Variable, Goal is unified with true.
Calls Goal when Condition becomes true. The portable conditions are: nonvar/1, ground/1, (,)/2, and (;)/2.
Supported backend Prolog systems: ECLiPSe, SICStus Prolog, SWI-Prolog, and YAP.