What is the palace corner cannon (士角炮) opening?
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
士角炮, the palace corner cannon, is a first move like 炮二平四 (C2=4): the cannon slides onto the rib file, landing on the front corner of its own palace. It is a quieter alternative to the Central Cannon, keeping the cannon close to home and flexible rather than aiming straight down the centre.
Where the cannon ends up
Cannons start on the third rank, which is also the front rank of the palace. Moving one to file 4 or 6 puts it on the palace's front corner point, two points up the file from an advisor's starting square. From there it watches the rib file, supports the centre, and can later swing to the centre or out to a wing. It is different from the Cannon Across the Palace, where the cannon moves past the centre to the rib on the other side.
What the choice means
Like other non-central first moves, it gives up the immediate pressure of the Central Cannon in exchange for flexibility, so the opponent has more freedom in the first few moves. It is a matter of style rather than a trick, and specific lines matter more than the name. Choosing an opening discusses how to pick between central and non-central starts.
A practical warning
A cannon on the palace corner can get in the way of your own horse or advisor if you develop carelessly, since it is standing right at the palace edge. Plan which way the horse on that side will go before playing it. See the rib for why that file matters.
Related questions
Is 士角炮 the same as 過宮炮?
No. The palace corner cannon moves to the rib on its own side (C2=4); the Cannon Across the Palace moves across to the far rib (C2=6).
Can Black play it too?
Yes, as a first reply or later in development; the idea is the same from either side.
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