(VAR x y) (RULES app(app(plus, x), 0) -> x app(app(plus, x), app(s, y)) -> app(s, app(app(plus, x), y)) app(app(app(f, 0), app(s, 0)), x) -> app(app(app(f, x), app(app(plus, x), x)), x) app(app(g, x), y) -> x app(app(g, x), y) -> y ) (STRATEGY INNERMOST)