Can a cannon give check without a screen?
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
No. Check means the general could be captured next move, and a cannon cannot capture without exactly one screen. A cannon pointing at the general down an empty line is giving no check at all — which is precisely why a lone cannon cannot mate a bare general in an empty palace.
It cuts both ways in defence
If an enemy cannon is checking you across a screen, you have three answers instead of the usual two: capture the cannon, move the general — or remove the screen, which switches the check off without touching the cannon.
Removing the screen is the answer that gets missed, and it is often the cheapest one available.
And in attack
Conversely, dropping any piece onto an empty line between your cannon and the enemy general creates a check out of nothing. That is the basis of most discovered checks in xiangqi, and it is the opposite of the chess intuition, where you open lines rather than fill them.
Related questions
Can adding a piece create check?
Yes, if it becomes the single screen for a cannon already aimed at the general. Your own piece works as well as your opponent's.
Can two screens block a cannon's check?
Yes. Exactly one is required; a second piece on the line switches it off entirely.
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