5

"Pin" and "skewer" are fairly common terms in chess:

  • A pin is a situation where a piece cannot move without exposing a more valuable piece to attack. For example, the Ruy Lopez Opening features a black knight pinned (against the black king) by a white bishop after white's third move.

  • A skewer is when a piece is attacked and moving it would expose a less valuable piece to attack. An example would be a black rook attacking a white queen along a file with a white rook on the same file behind the queen.

However, I am unaware of a term applying to a similar situation in which the attacked piece is of equal value to the piece it is shielding, whether because they are two pieces of the same type (e.g. rooks) or the same value (bishop and knight, using "conventional" values of 3 pawns/points for both knights and bishops). Does such a term exist? If so, what is it? Or do we just use "pin" (or "skewer")?

This diagram shows an example with a white bishop attacking two black rooks along the same diagonal. (The black pawn is to rule out the possible responses Ra5 and Rb5, which distract from the point of the example.)

r7/1r2k3/8/1p1BK3/8/8/8/8 w - - 0 1

 

Update: In some answers and comments there seems to some confusion about what a pin is and what a skewer is. Hopefully a couple examples will help clarify things.

First, a pin:

7k/q7/n7/8/8/Q2B4/1P6/1KN5 w - - 0 1

Black's knight is pinned as moving it exposes their more valuable queen to attack by White's queen.

A skewer:

7r/k5q1/6p1/8/8/2B5/1P6/1KR5 w - - 0 1

Black's queen is skewered against their less valuable rook, as once the queen moves away from the bishop's attack, their (black's) rook can be captured.

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  • 2
    @theonlygusti in a fork you are directly attacking two pieces, in this situation right now you are only attacking the rook on B7. You would only be attacking the rook on A8 if the rook on B7 moves out of the way or is taken by the bishop
    – Darren H
    May 13, 2021 at 15:14
  • @theonlygusti I'd argue that they are wrong, those positions are not a fork. The position you stated in the FEN is a pin, not a fork. See more at en.wikipedia.org/wiki/Fork_(chess) . I have checked all the references in that article, especially the links to chess.com and lichess.org and neither mention any positions that are pins/skewers while referring to them as forks
    – Darren H
    May 16, 2021 at 14:47

5 Answers 5

11

I'm not aware of any terms. Maybe it is helpful to think instead of the purpose of the move:

  • pin: preventing a piece from moving by threatening to attack a piece behind it
  • skewer: forcing a piece to move, in order to attack the piece behind it

So whether you call a situation with a knight in front of a bishop (or rook in front of a rook like in your board) a "skewer" or a "pin" depends perhaps on what the primary intention is.

In your board position, I would say that the A8 rook is skewered and the B7 rook is pinned.

5

Simply call it a "double attack". The bishop is attacking the b7 rook directly and the a8 rook by x-ray. Of course pins & skewers involve an x-ray. But there are many double attacks ; some do & some do not involve an x-ray.

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  • 2
    How about "x-ray double attack"? This is the most specific and applies best to the description of the poster. May 7, 2021 at 7:59
3

I call it a kebab. That's the only name I can think of for it.

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  • 1
    Welcome to Chess Stack Exchange! This may be a good suggestion, but Stack Exchange is meant to provide established answers, not for inventing new terms on the spot. There's a small chance your invention may stick; if not, don't be disappointed if this answer is eventually removed.
    – Glorfindel
    Feb 6 at 20:19
  • @Glorfindel Fortunately, there is a plurality of views in SE. This is a newly identified corner case, and as such a new whimsical name is appropriate, and consistent with the boisterous nature of chess naming (fried liver, bong, etc) What would make my stomach turn is to stretch some existing term and pretend that it already covered this case. If some dull person tries to remove this answer don’t be disappointed if I take this to meta.
    – Laska
    Feb 17 at 2:19
1

In the position you have shown as part of the question, it would still be called a skewer. The white bishops skewers the black rook on b7. Pins and Skewers are decided by the value of your piece (bishop, 3 points) vs the value of the piece under threat (rook, 5 points).

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  • 1
    That's not what the terms "pin" and "skewer" mean. The value of the attacking piece is not what determines which term applies. Instead, a pin is when one side's piece attacks an opposing piece in front of a more valuable piece of the opponent; e.g. your bishop attacks a rook with a queen aligned behind it on the same diagonal. A skewer is when the more valuable piece is the one directly attacked with the less valuable piece of the same color behind it; such as a king being attacked along a file by a rook with the queen of the same color as the king is behind that king on that file.
    – GreenMatt
    Feb 5 at 18:40
0

Skewer is the term used in a very similar puzzle (bishop attacking a rook with a second rook behind the first on the same diagonal) in the Chessable Course titled "Chessable Challenge".

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  • This weakens your argument in a comment to anti - Marshall 's answer.
    – Evargalo
    Feb 16 at 7:50
  • @Evargalo: No. The point I make under anti-Marshall's answer is that his definitions of "pin" and "skewer" are wrong.
    – GreenMatt
    Feb 16 at 14:00
  • But aren't you saying in this answer that Chessable is using the same defintion of skewer as anti-Marshall ?
    – Evargalo
    Feb 16 at 15:28
  • @Evargalo: The problem with anti-Marshall's definition of a skewer is that they state that the value of the attacking piece is what makes an attack a skewer or pin, which is incorrect. It's the value of the (directly) attacked piece vs. the value of the same side's piece it is in front of.
    – GreenMatt
    Feb 16 at 17:52

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