Mate in 7 — Problem #2997247
Black to move — find the mate
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9
8
7
6
5
4
3
2
1
一
二
三
四
五
六
七
八
九
☗
Show solution
▲３一角成 △５一玉 ▲４二角 △６二玉 ▲５三角不成 △５一玉 ▲４二馬
Why this move works
The answer is ▲３一角成 △５一玉 ▲４二角 △６二玉 ▲５三角不成 △５一玉 ▲４二馬, a seven-move mate using two bishops in tandem. ▲３一角成 first makes a horse, the second bishop is deployed with ▲４二角 → ▲５三角不成, and finally ▲４二馬 mates, anchored by the bishop on 5三.
One bishop becomes the attacking horse while the other turns into its support — a two-bishop combination. Checking with the horse while the bishop’s diagonal pre-emptively seals the king’s escape is the backbone.