The membership command is applicable to a name in a goal, where the name refers to an element or injection of a free type. It makes the membership constraint implied by the free type available as an antecedent in the sub-goal.
Given the general form of a free type,
f1 ::= h1,1 ... h1,m1 | g1,1 ![]() ![]() ![]() ![]() |
& ... & |
fr ::= hr,1 ... hr,mr | gr,1 ![]() ![]() ![]() ![]() |
the membership constraint for an element is
hi,j ![]() |
and the membership constraint for an injection is
gi,k ![]() ![]() ![]() |
"membership" e1 e2
This example applies the membership command to expressions e1 and e2.