(VAR x y )
(RULES 
        f(true,x,y) -> f(gt(x,y),double(x),s(y))
        gt(s(x),0) -> true
        gt(0,y) -> false
        gt(s(x),s(y)) -> gt(x,y)
        double(x) -> plus(x,x)
        plus(0,y) -> y
        plus(s(x),y) -> plus(x,s(y))
        
)