MAYBE

Problem:
 app(app(max(),0()),x) -> x
 app(app(max(),x),0()) -> x
 app(app(max(),app(s(),x)),app(s(),y)) -> app(app(max(),x),y)
 app(app(min(),0()),x) -> 0()
 app(app(min(),x),0()) -> 0()
 app(app(min(),app(s(),x)),app(s(),y)) -> app(app(min(),x),y)
 app(app(app(app(insert(),f),g),nil()),x) -> app(app(cons(),x),nil())
 app(app(app(app(insert(),f),g),app(app(cons(),h),t)),x) ->
 app(app(cons(),app(app(f,x),h)),app(app(app(app(insert(),f),g),t),app(app(g,x),h)))
 app(app(app(sort(),f),g),nil()) -> nil()
 app(app(app(sort(),f),g),app(app(cons(),h),t)) ->
 app(app(app(app(insert(),f),g),app(app(app(sort(),f),g),t)),h)
 app(ascending_sort(),l) -> app(app(app(sort(),min()),max()),l)
 app(descending_sort(),l) -> app(app(app(sort(),max()),min()),l)

Proof:
 Open