(from AG01 3.6) (VAR x y) (RULES le(0,y) -> true le(s(x),0) -> false le(s(x),s(y)) -> le(x,y) pred(s(x)) -> x minus(x,0) -> x minus(x,s(y)) -> pred(minus(x,y)) gcd(0,y) -> y gcd(s(x),0) -> s(x) gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y)) if_gcd(true,s(x),s(y)) -> gcd(minus(x,y),s(y)) if_gcd(false,s(x),s(y)) -> gcd(minus(y,x),s(x)))