Can a cannon cause a perpetual chase 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 that keeps renewing a threat on the same undefended enemy piece, on every one of its side's moves while the position repeats, is committing a perpetual chase, and under the repetition rules the side doing the chasing is the one required to vary, or it loses.
Switching the threat on and off
Because a cannon's threat can be turned on or off just by adding or removing a screen, it is tempting to think that each new threat counts as a fresh one. Repetition rules look past the mechanism: a chase has to be renewed on every one of the chasing side's moves, and a move that switches the threat off is a move that did not chase.
How it is normally resolved
The chasing side has to vary: capture the piece if it can, or turn to a genuinely different plan. If it keeps repeating the chase while the other side breaks no rule, the chaser loses. See perpetual check and chase for how arbiters and engines judge exactly what counts as chasing.
Related questions
Does chasing a defended piece with a cannon count the same way?
Usually not: a threat on a properly defended piece is generally not a prohibited chase. The exception that matters for a cannon is a chariot. A cannon for a chariot is a good trade anyway, so chasing a defended chariot still counts.
Is this specific to cannons?
No, any piece except the general and the soldiers can be the chasing piece; the cannon's on-off screen trick just makes it a particularly common source of borderline cases.
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