What is over-protection in xiangqi, and when is it worth it?
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
Over-protection means putting more defenders on a key point than the position currently requires, so that later, when a defender is pulled away to support an attack elsewhere, the point does not become weak. It is worth doing when a specific point is both important to hold and likely to lose a defender soon.
Why more defence than necessary can still be efficient
A point defended exactly once is fine until that single defender is needed somewhere else, at which point the point becomes weak the moment it moves. A point defended twice can release one defender for other duty while remaining just as safe as before, which is the entire value of the extra investment.
When it is not worth the tempo
Over-protecting a point that is unlikely to come under real pressure, or that no piece will need to leave anytime soon, just spends moves for no practical benefit. The technique earns its keep specifically around points you expect to both need and eventually need to redeploy a defender away from.
Related questions
Is this the same idea as prophylaxis?
Related but narrower; see prophylaxis for the broader habit of anticipating a threat before it exists.
Is over-protection a beginner-level idea?
It is more useful once basic tactics and development are solid, since it requires judging future needs rather than reacting to the current position alone.
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