Does an open file help a cannon the way it helps a chariot?
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
Not in the same way, and sometimes not at all. A chariot's power grows directly with how clear its lines are. A cannon needs a screen to threaten anything, so a fully open file can actually leave a cannon with nothing to capture or check, while a file with exactly one well-chosen piece on it is often far more dangerous.
Where the intuition from chess misleads
Chess-trained instincts say open lines are always good for a long-range piece. For a cannon that is only half true: an open file is good for repositioning quickly along it, but the cannon's actual threats come from lines with a single screen, which an open file by definition does not have.
What a cannon actually wants
A file or rank with exactly one piece between the cannon and a valuable target, ideally a piece the opponent cannot easily remove without cost. That is a completely different shape from the wide-open lines a chariot is hunting for, even though both pieces move similarly along clear ground.
Related questions
So is an open file ever useful to a cannon?
Yes, for mobility and repositioning to a better file, just not directly for attacking down it.
Can a cannon and chariot want different things on the same file?
Yes, and reconciling that is a real part of coordinating them together.
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