We present a way to lift up the tower lowerbound of the reachability problem for Petri nets to match the Ackermannian upperbound closing a long standing open problem. We also prove that the reachability problem in fix dimension is not elementary.

翻译：我们提出一种方法来提升Petri网可达性问题的低端塔塔,以配合阿克曼人顶端的Ackermannian上层封闭一个长期存在的未决问题。 我们还证明固定层面的可达性问题不是最基本的问题。