(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))))))
        
)