Find 2 chess positions in which the only move is a promotion to a knight, or bishop (1 position for each piece).
However the goal of the underpromotion must NOT be one of the following :
- Preventing a stalemate
- Achieving checkmate (or achieving checkmate faster than without underpromotion)
Additional rules :
- The promoting side may not lose the game with perfect play from both sides
- Insufficient material / 3-fold repetition / 50-move rule draws cannot happen (In order to prevent trivial king-queen forks)
Can you figure it out? The positions do not have to be reachable in a legal chess game.
Bonus questions (I haven't found an answer to these questions, so they are not required to be marked as accepted):
1) Find a position following the same principle, but with a rook promotion instead.
2) Find legal positions following the same principle with knight/bishop/rook promotion.