I am writing a simple chess game in which I have to determine the end game conditions. My algorithm requires the piece that is putting the opponent king in check, and checks the following:
- King cannot escape
- Piece cannot be eliminated
- Path cannot be blocked
If all three conditions satisfy, then it is checkmate. However, I am wondering if there can be more than one piece simultaneously putting a king in check. It doesn't seem to be possible, but I can't come up with a proof for it. For example, is it possible for 2 rooks to put a king in check at the same time? Personally, I don't think that it's possible.