fmod MEMBER is 
	sorts MyItem MyBool MyList InVec .
	 
	*** DT definitions (constructors)
	op t : -> MyBool [ctor] .
	op f : -> MyBool [ctor] .
	op [] : -> MyList [ctor] .
	op cons : MyItem MyList -> MyList [ctor] .
	 
	*** defined function names (to be induced, preds, bk)
	op mem : MyItem MyList -> MyBool [metadata "induce"] .
	*** input encapsulation
	op in : MyItem MyList -> InVec [ctor] .
	 
	vars U V W X Y Z : MyItem .

	eq mem(W,[]) = f .
	eq mem(W,cons(Y,[])) = f .
	eq mem(W,cons(Y,cons(Z,[]))) = f .
	eq mem(Y,cons(X,cons(Y,cons(W,[])))) = t .
endfm