(from AG01 3.8a) (VAR x y) (RULES pred(s(x)) -> x minus(x,0) -> x minus(x,s(y)) -> pred(minus(x,y)) quot(0,s(y)) -> 0 quot(s(x),s(y)) -> s(quot(minus(x,y),s(y))) log(s(0)) -> 0 log(s(s(x))) -> s(log(s(quot(x,s(s(0)))))) )