(VAR fun x xs y )
(RULES 
        app(f,app(s,x)) -> app(f,x)
        app(g,app(app(cons,0),y)) -> app(g,y)
        app(g,app(app(cons,app(s,x)),y)) -> app(s,x)
        app(h,app(app(cons,x),y)) -> app(h,app(g,app(app(cons,x),y)))
        app(app(map,fun),nil) -> nil
        app(app(map,fun),app(app(cons,x),xs)) -> app(app(cons,app(fun,x)),app(app(map,fun),xs))
        app(app(filter,fun),nil) -> nil
        app(app(filter,fun),app(app(cons,x),xs)) -> app(app(app(app(filter2,app(fun,x)),fun),x),xs)
        app(app(app(app(filter2,true),fun),x),xs) -> app(app(cons,x),app(app(filter,fun),xs))
        app(app(app(app(filter2,false),fun),x),xs) -> app(app(filter,fun),xs)
        
)