Nope, unless your gonna count x-ray vision from the second doubled rook
Only one check can be given by moving a piece
Only one check can be given by a piece through where the last piece was.
Only one check can be given by moving a piece
Only one check can be given by a piece through where the last piece was.
Impossible in standard chess, but possible with the addition a fairy piece: en.m.wikipedia.org/wiki/Nightrider_(chess)
An en passant capture could trigger a double discovered check by a nightrider and a rook while also attacking the king with the pawn.
An en passant capture could trigger a double discovered check by a nightrider and a rook while also attacking the king with the pawn.
Never ever, except for illegal moves.
The "3rd" check could only be an existing one.Hypothetically.Add a discovered double-check...et voila! Pretty much what @Sarg0n said.
In addition to #2, you can actually give a double "discovered" check by taking en passant. But still no triple check.
It's a great question, and difficult to explain why not. One can see how a N+ can discover a R+ or a B+, yet it seems it can't discover both at the same time. It's impossible to place a rook and bishop attacking the same square with another single square in the line of fire of both (where one could have placed the N to move away and discover two checks). The reason is that a diagonal and a vertical/horizontal can intersect only once. If that intersecting square is the king's square, no other single square can block them both. If a single square blocks them both, then there is no second square that they would both attack if the blocking piece were removed.
First, we must start from a definition of "number of pieces checking". That would be defined as the number of pieces that could, had it hypothetically been their turn to move, captured the king with a legal move.
Let's start from a position where a king would be in triple check and work backward.
Before the previous move, the side that is not to move must not be in check, otherwise their previous move must have been illegal, as it would have resulted in the king being in check (neither king is in check in the initial position).
Thus, for there to be a triple check, the last move must have increased the amount of pieces checking from zero to three.
Now a piece can go from not checking to checking the opposing king during a move of its camp in two different ways:
(1) That piece moves to a new position (and/or promotes or otherwise changes its movement rules) to where it is placing the opposing king in check.
(2) Movements of other pieces cause a piece that was previously not checking to now be checking.
The first way is limited to one piece, as only one piece actually moves (as opposed to being captured) during any legal move.
For the second way, we note that no piece in chess gains additional movements from the presence of other pieces, but some (specifically the bishop, rook, and queen) do lose movements when they are impeded by other pieces.
Thus, squares that were occupied before the last move but are empty after could result in the creation of additional checks.
However, in all possible moves except en passant captures, only one previously occupied square is made empty.
Now we can make another observation, and that is that vacating one square cannot cause two pieces to attack the enemy king that did not previously do so, as neither the orthogonal moves of the rook nor the diagonal moves of the bishop (nor any moves of the queen) are curved, so they cannot intersect first at one point, and then at the enemy king, unless they are both on the same ray of the line passing through the enemy king and the square vacated, and continued from the vacated square away from the king. In that case, one of the two must be closer to the vacated square, and it would inevitably prevent the other from attacking the king. This is an important property of the rules that those pieces move by, which is that they can make repeated steps of equal size along a straight line, and can go no further whenever they meet an obstacle.
Thus, for all moves except en passant, only one piece moves to a new square, and only one can be unblocked, so triple check is impossible.
In the case of an en passant capture, two squares are vacated, and one piece is moved to a new square. For this to result in a triple check, the capturing pawn must be giving check from its new position, and both vacated squares must unblock attacks by other pieces.
However, this is impossible because given an en passant capture, the squares that are attacked by the capturing pawn are a knight's move from the square vacated by the captured pawn, so for a triple check one of the pieces must be unblocked by the opening of a square a knight's move from its target. This is impossible for normal chess pieces, but as @RapidVariants mentioned would be possible given a piece that can make repeated knight's moves until it encounters an obstacle, and can proceed no further, such a piece is known as a Nightrider.
Thus, triple checks are impossible in standard chess, but could be possible in variants with Nightriders, pieces that move along curved trajectories and are obstructed by obstacles, pieces that make uneven steps and are obstructed by obstacles, or other movement rules.
I hope you find this proof sufficiently clear to understand, if you are confused by it, feel free to ask me for clarification.
Let's start from a position where a king would be in triple check and work backward.
Before the previous move, the side that is not to move must not be in check, otherwise their previous move must have been illegal, as it would have resulted in the king being in check (neither king is in check in the initial position).
Thus, for there to be a triple check, the last move must have increased the amount of pieces checking from zero to three.
Now a piece can go from not checking to checking the opposing king during a move of its camp in two different ways:
(1) That piece moves to a new position (and/or promotes or otherwise changes its movement rules) to where it is placing the opposing king in check.
(2) Movements of other pieces cause a piece that was previously not checking to now be checking.
The first way is limited to one piece, as only one piece actually moves (as opposed to being captured) during any legal move.
For the second way, we note that no piece in chess gains additional movements from the presence of other pieces, but some (specifically the bishop, rook, and queen) do lose movements when they are impeded by other pieces.
Thus, squares that were occupied before the last move but are empty after could result in the creation of additional checks.
However, in all possible moves except en passant captures, only one previously occupied square is made empty.
Now we can make another observation, and that is that vacating one square cannot cause two pieces to attack the enemy king that did not previously do so, as neither the orthogonal moves of the rook nor the diagonal moves of the bishop (nor any moves of the queen) are curved, so they cannot intersect first at one point, and then at the enemy king, unless they are both on the same ray of the line passing through the enemy king and the square vacated, and continued from the vacated square away from the king. In that case, one of the two must be closer to the vacated square, and it would inevitably prevent the other from attacking the king. This is an important property of the rules that those pieces move by, which is that they can make repeated steps of equal size along a straight line, and can go no further whenever they meet an obstacle.
Thus, for all moves except en passant, only one piece moves to a new square, and only one can be unblocked, so triple check is impossible.
In the case of an en passant capture, two squares are vacated, and one piece is moved to a new square. For this to result in a triple check, the capturing pawn must be giving check from its new position, and both vacated squares must unblock attacks by other pieces.
However, this is impossible because given an en passant capture, the squares that are attacked by the capturing pawn are a knight's move from the square vacated by the captured pawn, so for a triple check one of the pieces must be unblocked by the opening of a square a knight's move from its target. This is impossible for normal chess pieces, but as @RapidVariants mentioned would be possible given a piece that can make repeated knight's moves until it encounters an obstacle, and can proceed no further, such a piece is known as a Nightrider.
Thus, triple checks are impossible in standard chess, but could be possible in variants with Nightriders, pieces that move along curved trajectories and are obstructed by obstacles, pieces that make uneven steps and are obstructed by obstacles, or other movement rules.
I hope you find this proof sufficiently clear to understand, if you are confused by it, feel free to ask me for clarification.
It's not a great question at all..it's a spam thread
@bunyip
I agree that for a proven moron with a 1200 rating, a question that forces one to think is not great at all.
I agree that for a proven moron with a 1200 rating, a question that forces one to think is not great at all.
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