
poss(?SetVariable, -Poss)

   Obtaining the still possible elements of a set (lub\glb)

Arguments
   SetVariable         A set variable.
   Poss                A set.

Type
   library(cardinal)

Description
Poss is unified with the set of still possible elements of SetVariable
		(i.e. its lub\glb).
		If SetVariable is a set of sets and a union function attribute has been set,
		then each element of Poss comes annotated with its respective length.

Fail Conditions
   Fails if Poss can not be unified with the current poss (lub\glb) of SetVariable.

Resatisfiable
   No.

Examples
   
?- S `::[c]+[a,b], poss(S,P).
P = [a,b]

?- S `::[[c]]+[[a,b]], poss(S,P).
P = [[a,b]]

?- set(S, [],[[a,b],[b,c],[a,c],[b]],[union:[a,b,c]]), poss(S,P).
P = [[a, b] : 2, [a, c] : 2, [b] : 1, [b, c] : 2]


See Also
   glb / 2, glb_poss / 3, domain / 2, domain / 3, lub / 2, lub / 4
