H. G. Muller wrote on Sun, Nov 17, 2019 01:06 PM EST:
That certainly makes more sense to me. One could still wonder about the case where the first-moved Bishop does not convert, but is captured before the second moves. The situation this gives rise to is not really any different from the one where it was captured before it moved. And you would need extra game state to distinguish the two.
I guess you need extra game state anyway, because a Bishop can move and return to his starting square without converting. The other Bishop must then convert, but from the board position you cannot see which of the two is the 'other' Bishop.
Possibly the cleanest solution to everything is to implement this by piece-type changing: start both Bishops as Dragon Horses. When a Dragon Horse moves, it 'promotes' to Bishop, and as a side effect, depending on how it moves, the other Dragon Horse (which must still be on its starting square in that case if not captured), promotes, either to Wazir or to Bishop. If a Wazir moves it always promotes to Bishop. All game state is then encoded in the board position.
That certainly makes more sense to me. One could still wonder about the case where the first-moved Bishop does not convert, but is captured before the second moves. The situation this gives rise to is not really any different from the one where it was captured before it moved. And you would need extra game state to distinguish the two.
I guess you need extra game state anyway, because a Bishop can move and return to his starting square without converting. The other Bishop must then convert, but from the board position you cannot see which of the two is the 'other' Bishop.
Possibly the cleanest solution to everything is to implement this by piece-type changing: start both Bishops as Dragon Horses. When a Dragon Horse moves, it 'promotes' to Bishop, and as a side effect, depending on how it moves, the other Dragon Horse (which must still be on its starting square in that case if not captured), promotes, either to Wazir or to Bishop. If a Wazir moves it always promotes to Bishop. All game state is then encoded in the board position.