Can a cannon give perpetual check in xiangqi?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws for movement, checkmate and both repetition rulings: a side that forces a repetition by perpetual check or perpetual chase loses rather than drawing. The chase half has not been validated against the official casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it before publishing.
Direct answer
Yes. A cannon can check repeatedly by moving along its lines, or by having a piece step onto its line to become the screen. Whichever mechanism produces it, if every one of a side's moves in the repeating cycle gives check, the ordinary perpetual check rule applies and the checking player must vary or lose. A move that gives no check breaks the perpetual.
Why the cannon makes this easy to fall into
Because a cannon's check depends on a screen rather than only on its own position, a player can renew a check by bringing a different piece onto the line as the screen, and it is easy not to notice that the same check keeps coming back. The rule looks past the mechanism and at the result: whether every one of your moves in the repeating cycle gives check.
What counts as varying
Genuinely changing the position, winning material, forcing the general somewhere new, or building a fresh threat, counts as variation. Switching which piece happens to be the screen while the check itself repeats does not, for the same reason discussed under whether perpetual check needs the same piece every time.
Related questions
Is this different from a cannon's perpetual chase?
Yes, chase targets an ordinary piece; this targets the general directly. See can a cannon cause a perpetual chase for the piece-chasing version.
Can I avoid this by checking with a different piece each time?
No. What matters is that the position keeps repeating while every one of your moves gives check, not which piece happens to be delivering it.
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