(VAR fun x xs y z )
(RULES 
        app(app(app(f,0),1),x) -> app(app(app(f,app(s,x)),x),x)
        app(app(app(f,x),y),app(s,z)) -> app(s,app(app(app(f,0),1),z))
        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)
        
)