(VAR x xs y z )
(RULES 
        times(x, y) -> sum(generate(x, y))
        generate(x, y) -> gen(x, y, 0)
        gen(x, y, z) -> if(ge(z, x), x, y, z)
        if(true, x, y, z) -> nil
        if(false, x, y, z) -> cons(y, gen(x, y, s(z)))
        sum(nil) -> 0
        sum(cons(0, xs)) -> sum(xs)
        sum(cons(s(x), xs)) -> s(sum(cons(x, xs)))
        ge(x, 0) -> true
        ge(0, s(y)) -> false
        ge(s(x), s(y)) -> ge(x, y)
        
)