Def deq-member(eq;x;L) == reduce(a,b. eqof(eq)(a,x)  b;false;L)

is mentioned by

Thm* eq:EqDecider(A), L:A List, x:A. deq-member(eq;x;L)  (x  L)

[assert-deq-member]

Try larger context: EventSystems IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html