MAYBE
0.18/0.21	MAYBE
0.18/0.21	
0.18/0.21	Problem:
0.18/0.21	 active(zeros()) -> mark(cons(0(),zeros()))
0.18/0.21	 active(U11(tt(),L)) -> mark(s(length(L)))
0.18/0.21	 active(and(tt(),X)) -> mark(X)
0.18/0.21	 active(isNat(0())) -> mark(tt())
0.18/0.21	 active(isNat(length(V1))) -> mark(isNatList(V1))
0.18/0.21	 active(isNat(s(V1))) -> mark(isNat(V1))
0.18/0.21	 active(isNatIList(V)) -> mark(isNatList(V))
0.18/0.21	 active(isNatIList(zeros())) -> mark(tt())
0.18/0.21	 active(isNatIList(cons(V1,V2))) -> mark(and(isNat(V1),isNatIList(V2)))
0.18/0.21	 active(isNatList(nil())) -> mark(tt())
0.18/0.21	 active(isNatList(cons(V1,V2))) -> mark(and(isNat(V1),isNatList(V2)))
0.18/0.21	 active(length(nil())) -> mark(0())
0.18/0.21	 active(length(cons(N,L))) -> mark(U11(and(isNatList(L),isNat(N)),L))
0.18/0.21	 active(cons(X1,X2)) -> cons(active(X1),X2)
0.18/0.21	 active(U11(X1,X2)) -> U11(active(X1),X2)
0.18/0.21	 active(s(X)) -> s(active(X))
0.18/0.21	 active(length(X)) -> length(active(X))
0.18/0.21	 active(and(X1,X2)) -> and(active(X1),X2)
0.18/0.21	 cons(mark(X1),X2) -> mark(cons(X1,X2))
0.18/0.21	 U11(mark(X1),X2) -> mark(U11(X1,X2))
0.18/0.21	 s(mark(X)) -> mark(s(X))
0.18/0.21	 length(mark(X)) -> mark(length(X))
0.18/0.21	 and(mark(X1),X2) -> mark(and(X1,X2))
0.18/0.21	 proper(zeros()) -> ok(zeros())
0.18/0.21	 proper(cons(X1,X2)) -> cons(proper(X1),proper(X2))
0.18/0.21	 proper(0()) -> ok(0())
0.18/0.21	 proper(U11(X1,X2)) -> U11(proper(X1),proper(X2))
0.18/0.21	 proper(tt()) -> ok(tt())
0.18/0.21	 proper(s(X)) -> s(proper(X))
0.18/0.21	 proper(length(X)) -> length(proper(X))
0.18/0.21	 proper(and(X1,X2)) -> and(proper(X1),proper(X2))
0.18/0.21	 proper(isNat(X)) -> isNat(proper(X))
0.18/0.21	 proper(isNatList(X)) -> isNatList(proper(X))
0.18/0.21	 proper(isNatIList(X)) -> isNatIList(proper(X))
0.18/0.21	 proper(nil()) -> ok(nil())
0.18/0.21	 cons(ok(X1),ok(X2)) -> ok(cons(X1,X2))
0.18/0.21	 U11(ok(X1),ok(X2)) -> ok(U11(X1,X2))
0.18/0.21	 s(ok(X)) -> ok(s(X))
0.18/0.21	 length(ok(X)) -> ok(length(X))
0.18/0.21	 and(ok(X1),ok(X2)) -> ok(and(X1,X2))
0.18/0.21	 isNat(ok(X)) -> ok(isNat(X))
0.18/0.21	 isNatList(ok(X)) -> ok(isNatList(X))
0.18/0.21	 isNatIList(ok(X)) -> ok(isNatIList(X))
0.18/0.21	 top(mark(X)) -> top(proper(X))
0.18/0.21	 top(ok(X)) -> top(active(X))
0.18/0.21	
0.18/0.21	Proof:
0.18/0.21	 Open
0.18/0.21	EOF