MAYBE MAYBE TRS: { 0() -> n__0(), p(0()) -> 0(), p(s(X)) -> X, s(X) -> n__s(X), leq(0(), Y) -> true(), leq(s(X), 0()) -> false(), leq(s(X), s(Y)) -> leq(X, Y), activate(X) -> X, activate(n__0()) -> 0(), activate(n__s(X)) -> s(X), if(true(), X, Y) -> activate(X), if(false(), X, Y) -> activate(Y), diff(X, Y) -> if(leq(X, Y), n__0(), n__s(diff(p(X), Y))) } DUP: We consider a duplicating system. Trs: { 0() -> n__0(), p(0()) -> 0(), p(s(X)) -> X, s(X) -> n__s(X), leq(0(), Y) -> true(), leq(s(X), 0()) -> false(), leq(s(X), s(Y)) -> leq(X, Y), activate(X) -> X, activate(n__0()) -> 0(), activate(n__s(X)) -> s(X), if(true(), X, Y) -> activate(X), if(false(), X, Y) -> activate(Y), diff(X, Y) -> if(leq(X, Y), n__0(), n__s(diff(p(X), Y))) } Fail