scheme :: CIRCCOMB:sch 1
MSSLambdaWeak{ F1() -> set , F2() -> set , F3() -> Function of F1(),F2(), F4( object , object ) -> object } :
ex f being ManySortedSet of F1() st
for a being set
for b being Element of F2() st a in F1() & b = F3() . a holds
f . a = F4(a,b)