(VAR L X X1 X2 XS Y YS )
(RULES 
        active(app(nil, YS)) -> mark(YS)
        active(app(cons(X, XS), YS)) -> mark(cons(X, app(XS, YS)))
        active(from(X)) -> mark(cons(X, from(s(X))))
        active(zWadr(nil, YS)) -> mark(nil)
        active(zWadr(XS, nil)) -> mark(nil)
        active(zWadr(cons(X, XS), cons(Y, YS))) -> mark(cons(app(Y, cons(X, nil)), zWadr(XS, YS)))
        active(prefix(L)) -> mark(cons(nil, zWadr(L, prefix(L))))
        active(app(X1, X2)) -> app(active(X1), X2)
        active(app(X1, X2)) -> app(X1, active(X2))
        active(cons(X1, X2)) -> cons(active(X1), X2)
        active(from(X)) -> from(active(X))
        active(s(X)) -> s(active(X))
        active(zWadr(X1, X2)) -> zWadr(active(X1), X2)
        active(zWadr(X1, X2)) -> zWadr(X1, active(X2))
        active(prefix(X)) -> prefix(active(X))
        app(mark(X1), X2) -> mark(app(X1, X2))
        app(X1, mark(X2)) -> mark(app(X1, X2))
        cons(mark(X1), X2) -> mark(cons(X1, X2))
        from(mark(X)) -> mark(from(X))
        s(mark(X)) -> mark(s(X))
        zWadr(mark(X1), X2) -> mark(zWadr(X1, X2))
        zWadr(X1, mark(X2)) -> mark(zWadr(X1, X2))
        prefix(mark(X)) -> mark(prefix(X))
        proper(app(X1, X2)) -> app(proper(X1), proper(X2))
        proper(nil) -> ok(nil)
        proper(cons(X1, X2)) -> cons(proper(X1), proper(X2))
        proper(from(X)) -> from(proper(X))
        proper(s(X)) -> s(proper(X))
        proper(zWadr(X1, X2)) -> zWadr(proper(X1), proper(X2))
        proper(prefix(X)) -> prefix(proper(X))
        app(ok(X1), ok(X2)) -> ok(app(X1, X2))
        cons(ok(X1), ok(X2)) -> ok(cons(X1, X2))
        from(ok(X)) -> ok(from(X))
        s(ok(X)) -> ok(s(X))
        zWadr(ok(X1), ok(X2)) -> ok(zWadr(X1, X2))
        prefix(ok(X)) -> ok(prefix(X))
        top(mark(X)) -> top(proper(X))
        top(ok(X)) -> top(active(X))
        
)