SkylarKnight wrote:
Minor detail, but I was doing a puzzle today with 2 solutions, but it gave me the incorrect mark (transposes into the same position).
This was the position (white to move)
White: Kh2, Ra1, a4
Black: Kb2, a5, b5
Both Ra2+ and Ra3 win for White, but chess.com only accepts Ra3.
Sample line:
1. Ra3, Kxa3 2. axb5, Kb2 3. b6, a4 4. b7, a3 5. b8Q+ Kc1
1. Ra2+ Kxa2 2. axb5, a4 3. b6, a3 4. b7, Kb2 5. b8Q, Kc1
As shown, it transposes to the exact same position, it’s just a known winning endgame for white if the pawn isn’t on a2
This was the position (white to move)
White: Kh2, Ra1, a4
Black: Kb2, a5, b5
Both Ra2+ and Ra3 win for White, but chess.com only accepts Ra3.
Sample line:
1. Ra3, Kxa3 2. axb5, Kb2 3. b6, a4 4. b7, a3 5. b8Q+ Kc1
1. Ra2+ Kxa2 2. axb5, a4 3. b6, a3 4. b7, Kb2 5. b8Q, Kc1
As shown, it transposes to the exact same position, it’s just a known winning endgame for white if the pawn isn’t on a2
For this puzzle, only Ra3 wins: https://www.chess.com/puzzles/problem/39368
Ra2+ is a draw
This was the position (white to move)
White: Kh2, Ra1, a4
Black: Kb2, a5, b5
Both Ra2+ and Ra3 win for White, but chess.com only accepts Ra3.
Sample line:
1. Ra3, Kxa3 2. axb5, Kb2 3. b6, a4 4. b7, a3 5. b8Q+ Kc1
1. Ra2+ Kxa2 2. axb5, a4 3. b6, a3 4. b7, Kb2 5. b8Q, Kc1
As shown, it transposes to the exact same position, it’s just a known winning endgame for white if the pawn isn’t on a2