LiChess puzzle 87510 has the following position:
[FEN "r1b1k3/pp4R1/2q3RQ/4p3/5P2/bP2P3/2P1K2P/8 b - - 0 1"]
The solution is 1...Bg4+
, after which white has 6 legal moves:
1...Bg4+ 2. Rxg4 Qxh6
, which is the computer solution (possibly followed by3. Rg8+ Bf8
),2. Kd3
, which is mate in 7,2. Kd2
, which is mate in 8,2. Ke1
, which is mate in 5,2. Kf1
, which is mate in 4, and2. Kf2
, which is mate in 4.
I feel like a human player in a tournament would not calculate the whole decision tree, and probably just intuit that 1...Bg4+
is going to win since black can continue with a range of powerful moves Qf3
, Qc2
, Rd8
, and Bb4
, and at least one of them is with check, depending on white's response.
Question: How much calculation would a strong player (say an FM+) perform before playing 1...Bg4+
?
It's a dangerous move: black begins with an exposed king (with mate threats and a possible rook skewer) and queen attacked, and black responds by creating an undefended bishop. If the checks ended, black would probably lose.