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81 votes

Why is this a checkmate?

To get out of check, the king needs to move to a square that isn't attacked by any opposing pieces, or you need to capture/block attacking pieces such that the king is no longer under attack on its ...
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  • 1,022
36 votes
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When capturing en passant, is a position possible such that there is a pin over the square of the taken pawn, rather than the taking pawn?

Really interesting question. I think the following shows that such a situation is sort of possible, depending on how you define the pin. [StartFlipped "0"] [FEN "7k/4p3/8/2KP3r/8/8/8/8 ...
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  • 7,398
26 votes

Why is this a checkmate?

Rook at d2 is pinned by the bishop at g5 and hence the rook can not capture the black queen at c2 checkmating the white king at c1.
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  • 620
26 votes

Why is this a checkmate?

Since you are a beginner in chess first you need to understand the term pin in chess. In chess, a pin is a situation brought on by an attacking piece in which a defending piece cannot move without ...
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  • 1,371
21 votes

Is this considered checkmate if I touch a piece which can't make a legal move?

No. The touch-move rule can't force you to make an illegal move, and it is not legal to put yourself in check. Here's what the FIDE laws of chess say: 4.5 If none of the pieces touched in ...
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  • 10.3k
15 votes

Why is exposing my queen for capture better in this position (According to computer analysis)?

Your description of the computer's suggestions doesn't quite match the position, but if you mean the computer suggests Nxe5, that is correct, as Bxd1 leads to a variation of Legal's Mate. Nxe5 Bxd1 ...
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12 votes
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Why don't masters prevent the pin after Bg4 in the modern Italian game?

You're referring to ...Bc8-g4 as a threat. The only threat it makes is ...Bg4xf3, losing time and the bishop pair. While White has d4 under wraps with a pawn at c3, theere's no ...Nc6-d4 coming to ...
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12 votes

Why is this a checkmate?

The original goal of chess was to capture the opponent’s king. The idea of “checkmate” follows this: you may as well call the game won/lost once capture next turn is inevitable. So you’re checkmated ...
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11 votes

Bizarre pin rule: pinned pieces do not attack

To answer the subquestion: "Does anyone know if this is some kind of known chess variant?" Yes, it is a known chess variant. It goes under several names including PMDNC (Pinned Men Do Not Check), Pin ...
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11 votes
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Failing to understand a pin from a tactics book

To me one move was clear - Nxd5 But after 1...cxd5 2.Rc7, although the knight is pinned for a move, Black can easily unpin it by moving the queen to d6, d8, e6, or e8. In fact, the knight ...
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  • 15.6k
10 votes
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How do you deal with the pinned knight on f3 in the Ruy Lopez (as white)?

Black cannot exploit the pin with ...Nd4: not at once because the Nc6 itself is pinned, not later because c2-c3 is on your plan anyway. This means that you should not panic and can concentrate on ...
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  • 12.9k
9 votes

When capturing en passant, is a position possible such that there is a pin over the square of the taken pawn, rather than the taking pawn?

On a related note, enjoy a chess problem that demonstrates the weird mechanism of the pawn being pinned by the taken pawn. I pulled this from Yet Another Chess Problem Database. [Title "Erich ...
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9 votes
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Why is Bd6 better than Be7, Bc5 and Bb4?

Part of the problem with Bc5 is that they can respond with Na4, which threatens the bishop and grabs the tempo. Be7 isn't great because its range is inhibited by the knight and it impedes the ...
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8 votes

How to handle the standard Bb4 (or Bg4 / Bg5 / Bb5) pin?

I realize that it's hard to give general guidelines here, since every chess position has unique considerations. Still, any rules of thumb would be appreciated. I would rather be right 80% of the time ...
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7 votes
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How to decide when is a3/h3 needed?

Let's stick to one color, white here, and everything we'll say will generally hold true for black as well. Rule of thumb: On the one hand, you generally don't want to move your king-side pawns (such ...
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  • 11.8k
7 votes

Is this considered checkmate if I touch a piece which can't make a legal move?

No, that's not a checkmate. The white bishop is currently pinned (in absolute pin because it protects the king from check by Black's rook), so there's no legal move can be made by that bishop. In ...
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7 votes

Pinned Vs. Checkmate

Think of it this way: Check mate is where nothing the opponent can do will save them from having you take their king on the next turn, so even if by putting their king in checkmate, you expose your ...
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7 votes
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Why pin knights early in the opening?

One of the key principles of opening play is that control of the center is vitally important. If one of the players has complete control of the center then they can much more easily launch an attack ...
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  • 77.4k
7 votes
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Why does White play Nc4?

it still seems to me that White wins more material playing Qb1 instead of what appeared to be the solution No, if you compare the two final positions the only difference is that in the Nc4 line white ...
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  • 77.4k
7 votes

Why is this a checkmate?

White can't move their rook from d2 as your bishop at g5 will capture the white's king.
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  • 87
7 votes
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Why is it a blunder to capture this pawn even if its defender is pinned?

Because you have opposite-colored bishops and it's nearly impossible to win in the endgame. You can, however, take advantage of the weak white king. After 20... Bxc3 the game will most likely continue:...
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  • 3,511
6 votes
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Capturing (almost) free piece by King

No, absolutely not. You are putting your king in check first from the Qd5. If you think about this way: Who could take the other king first since that really is what checkmate is? In this case, Kxg2 ...
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  • 32.1k
6 votes
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Chess Engine: Generate a Bitboard of Pinned Pieces

This task is nontrivial and cannot be obtained easily or setwise from the available bitboards. The following solution is an example for how such a task might be done for a generic slider - only ...
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  • 3,003
6 votes

An Interesting Idea: Pinned Pieces Stalemate

Bonus question : 4 pins stalemate without promoted piece. Here is a maximal solution with all 32 units : White's Rc2, Bd5, Nf2 and Ng6 are pinned. The king has no move and all the other white pieces ...
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  • 12.9k
6 votes

Pinned Vs. Checkmate

The rules are clear. A move that puts your king in check is an illegal move (I'll leave it to you to find the reference; you might find the other rules helpful to review once you get there). You ...
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  • 3,237
6 votes

Which opening contains this trap?

Adding to Philip's answer, I more remember it from the Scandinavian, because there the bQ gets out early anyway and it takes much less patzer moves to irreversibly trap it this way. Example: [FEN &...
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6 votes

Why is it a blunder to capture this pawn even if its defender is pinned?

Positions with opposite color bishops and heavy pieces are known to be very complicated and double-edged. The tension between two sides can last for a long time because of continuous maneouvering of ...
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5 votes

How to decide when is a3/h3 needed?

NEVER say never. Rules of thumb are just that. White very commonly plays h3 at an early stage in many variations of the Ruy Lopez, even before Black has committed his K. What often makes this safe is ...
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  • 7,518
5 votes

Failing to understand a pin from a tactics book

Regarding the question - how to deal with very hard tactics? I'd suggest moving to an easier tactics book, where everything will be clear for you. After you will finish that book, move to a more ...
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  • 1,010
5 votes
Accepted

Detect pinned pieces code

A: Let's use bishop for our example. xrayBishopAttacks works if we have the following position: but it doesn't work if you have this: The f3 knight is not pinned because there is something else ...
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  • 21.5k

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