What is prophylaxis in xiangqi, meaning preventing a combination before it exists?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws and is regression-tested against the official 110-diagram repetition casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it against the engine before publishing.
Direct answer
Prophylaxis means making a move that removes an opponent's future tactical resource before it becomes a real threat, rather than waiting to react once it actually appears on the board. It is preventive rather than responsive: the point is that the tactic you are stopping never quite gets the chance to happen.
What this looks like in practice
Noticing that a piece could, a few moves from now, reach a square that would fork two of your pieces, and quietly occupying or covering that square yourself before it becomes urgent, is prophylaxis. Nothing forces the move right now; it simply removes a problem while it is still cheap to remove.
Why it is a harder skill than reacting to threats
Reacting to an existing threat has an obvious trigger; preventing one requires noticing a danger that has not happened yet, which takes the same kind of forward-looking attention as a quiet move tactic, but pointed defensively rather than offensively. It is easy to under-value because a well-timed prophylactic move often looks, from the outside, like it did nothing at all.
Related questions
How do I train this specifically?
After finding your own best move in a position, ask what your opponent's best response would have created if you had played something else, and whether a small adjustment removes it in advance.
Is this the same as just being cautious?
No, caution is a general disposition; prophylaxis is a specific move aimed at a specific future resource you have identified.
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