Using the Filter Pushdown pattern, we would first match a pattern in the graph, then modify the tree at the point of the match. Here's the Filter Pushdown pattern to match

我们将首先利用FilterPushdown模式来匹配图中的某个模式，随后在匹配的点对树进行修改。

There is a very close relation between fuzzy pushdown automata and fuzzy context - free grammars.

:Fuzzy下推自动机与Fuzzy上下文无关文法有紧密的关系.

But concurrent pushdown systems simulate concurrency by global variables, which are not able to model event-drive concurrent programs.

但是并发下推系统以全局变量模拟同步，不适应于当前广泛使用的基于事件驱动的并发程序。