(VAR x y ) (RULES cond1(true, x, y) -> cond2(gr(x, y), x, y) cond2(true, x, y) -> cond3(gr(x, 0), x, y) cond2(false, x, y) -> cond4(gr(y, 0), x, y) cond3(true, x, y) -> cond3(gr(x, 0), p(x), y) cond3(false, x, y) -> cond1(and(gr(x, 0), gr(y, 0)), x, y) cond4(true, x, y) -> cond4(gr(y, 0), x, p(y)) cond4(false, x, y) -> cond1(and(gr(x, 0), gr(y, 0)), x, y) gr(0, x) -> false gr(s(x), 0) -> true gr(s(x), s(y)) -> gr(x, y) and(true, true) -> true and(false, x) -> false and(x, false) -> false p(0) -> 0 p(s(x)) -> x )