What is 雙車錯 (the two chariot mate)?
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
雙車錯 is two chariots mating with no other help at all. One chariot checks along the general's rank while the other controls the rank it would retreat to. Because a chariot sweeps a whole line in one move, two of them cover six of the palace's nine points — and the general only has three ranks.
The arithmetic
The general is locked in nine points. One chariot controls a whole rank of the palace, which is three of those nine. Two chariots on adjacent ranks control six, and the general cannot be on the remaining three and safe at the same time. That is the entire mate.
What follows for both sides
If your opponent has two chariots and your general is exposed, trading one is almost always right, even at the cost of a soldier — a single chariot cannot mate a general with any cover. If you have two, keeping both is correspondingly valuable.
Related questions
Can one chariot mate alone?
Against a bare general yes, with your own general's help. Against a general with cover, no.
Is it like a back-rank mate?
Same idea — control the lines the king cannot leave. The palace makes the net smaller and the mate faster.
.