We prove that king chasing problem in Chinese Chess is NP-hard when generalized to $n\times n$ boards. `King chasing' is a frequently-used strategy in Chinese Chess, which means that the player has to continuously check the opponent in every move until finally checkmating the opponent's king. The problem is to determine which player has a winning strategy in generalized Chinese Chess, under the constraints of king chasing. Obviously, it is a sub-problem of generalized Chinese Chess problem. We prove that king chasing problem in Chinese Chess is NP-hard by reducing from the classic NP-complete problem 3-SAT.

翻译：我们证明，当推广至$n\times n$棋盘时，中国象棋中的“长将”问题为NP难问题。“长将”是中国象棋中一种常用策略，指棋手必须每一步连续将军对方，直至最终将杀对方将（帅）。该问题旨在判定在长将约束下，广义中国象棋中哪一方具有必胜策略。显然，它是广义中国象棋问题的子问题。我们通过将经典NP完全问题3-SAT归约至该问题，证明了中国象棋中的长将问题为NP难的。