YES 1: f(x1) -> g(f(x1)) 2: h(x1) -> p(h(x1)) 3: f(x1) -> h(f(x1)) 4: g(x1) -> p(p(h(x1))) @Rule Labeling --- R 1: f(x1) -> g(f(x1)) 2: h(x1) -> p(h(x1)) 3: f(x1) -> h(f(x1)) 4: g(x1) -> p(p(h(x1))) --- S 1: f(x1) -> g(f(x1)) 2: h(x1) -> p(h(x1)) 3: f(x1) -> h(f(x1)) 4: g(x1) -> p(p(h(x1)))