🕸Fergus Duniho wrote on Sun, May 3, 2020 12:57 PM UTC:
I propose to change the definition of 'attack' by the following:
A piece is under attack when the opponent, would it be his turn, could *legally* capture it in the current position.
A square is under attack from a player when that player could *legally* capture an enemy piece standing on that square, given the remaining board occupation.
Colloquially, 'to attack' can also mean "play a move that creates one of the above situations".
Let me first clean up the English on this:
A piece is under attack if the opponent could, were it his turn, *legally* capture it in the current position.
A square is under attack from a player when that player could *legally* capture an enemy piece standing on that square, given the remaining board position.
Colloquially, 'to attack' can also mean "play a move that creates one of the above situations".
I disagree with the first two definitions. I'll start with the first. In Fusion Chess, for example, whether a compound piece is attacked affects whether it can split apart. This is unaffected by whether the attacking piece is unable to make the capture due to being pinned. Furthermore, this definition introduces a recursive factor into the evaluation of whether one piece is attacking another. To know whether one piece is attacking another, you would have to know how the powers of other pieces affect the movement of that piece.
I would propose the following instead:
1. One piece is attacking another when it has a capturing move that can reach its space, and it is normally allowed to capture or check that piece*. In situations where the only consequence to come from being attacked is being captured, an attack may be considered real only if a capture can actually be made. But in situations where attacking a piece can affect its powers of movement or the outcome of the game, it is normally assumed that other conditions in the game that could prevent the capture, such as being pinned, do not affect whether one piece is attacking another. For example, being pinned would not stop a piece from attacking the enemy king.
2. A space is under attack for a particular piece when moving there without any other changes to the position would expose it to attack in the first sense.**
3. Colloquially, "to attack" can also mean to play a move that creates one of the above situations.
* In most Chess variants, pieces are not allowed to capture pieces belonging to the same side, though exceptions may be made in individual variants. In Korean Chess, cannons are not allowed to capture each other even if they belong to different sides.
** In Chess, any space that is under attack for one piece will be under attack for all pieces belonging to the same side. But in other games, a space could be under attack for one piece but not for another. For example, if a black cannon were on a1, a white king on e1, a white rook on h1, and nothing else on the rank and nothing else attacking it, the spaces f1 and g1 would be under attack for the rook but not for the king. The restriction against castling through check would not stop the King from castling, though the restriction on moving into check would.
Let me first clean up the English on this:
I disagree with the first two definitions. I'll start with the first. In Fusion Chess, for example, whether a compound piece is attacked affects whether it can split apart. This is unaffected by whether the attacking piece is unable to make the capture due to being pinned. Furthermore, this definition introduces a recursive factor into the evaluation of whether one piece is attacking another. To know whether one piece is attacking another, you would have to know how the powers of other pieces affect the movement of that piece.
I would propose the following instead:
1. One piece is attacking another when it has a capturing move that can reach its space, and it is normally allowed to capture or check that piece*. In situations where the only consequence to come from being attacked is being captured, an attack may be considered real only if a capture can actually be made. But in situations where attacking a piece can affect its powers of movement or the outcome of the game, it is normally assumed that other conditions in the game that could prevent the capture, such as being pinned, do not affect whether one piece is attacking another. For example, being pinned would not stop a piece from attacking the enemy king.
2. A space is under attack for a particular piece when moving there without any other changes to the position would expose it to attack in the first sense.**
3. Colloquially, "to attack" can also mean to play a move that creates one of the above situations.
* In most Chess variants, pieces are not allowed to capture pieces belonging to the same side, though exceptions may be made in individual variants. In Korean Chess, cannons are not allowed to capture each other even if they belong to different sides.
** In Chess, any space that is under attack for one piece will be under attack for all pieces belonging to the same side. But in other games, a space could be under attack for one piece but not for another. For example, if a black cannon were on a1, a white king on e1, a white rook on h1, and nothing else on the rank and nothing else attacking it, the spaces f1 and g1 would be under attack for the rook but not for the king. The restriction against castling through check would not stop the King from castling, though the restriction on moving into check would.