Re: [math-fun] underpromotions in real chess games, 50 move rule, etc

Warren D Smith: "N-underpromo games..." Here's one from the endgame tablebases: 1Q4nr/8/4K3/6b1/8/8/2P5/3k4 w Mate in 538. The claim is that 1. с4 2. с5 4. с6 11. c7 12. c8=N are white's only winning moves.