Chess Tactics 1: The Absolute Pin

Here is what various sources have to say about the pin:

"Killer Chess Tactics" by Keene et al.:

"A pin is one of the most powerful weapons in all of chess. The simple pin is at the heart of many of the most complicated combinations. A piece is pinned when it cannot move off of the line on which it is attacked, if the result of moving would lead to the loss of a more important piece, which is a relative pin, or check to the king, which is an absolute pin. The basic method of exploiting a pin is to add as much pressure as possible to the pin."

"Chess Tactics from Scratch, Understanding Chess Tactics, 2nd edition" by Martin Weteschnik:

"Essentially a pin is a chain of three chess pieces. The first in this chain is the attacking piece, the second point is the pinned piece, and the third piece is the target of the pin."

"Winning Chess Combinations" by Hans Bouwmeester:

"Pins have a significant part to play at practically all stages of a game of chess. They can be set up without difficulty and just as easily parried. Nevertheless, a pin can have its dangers, and we must make it our business to recognize them in time."

In my opinion, a good way to simply pins would be to label the attacking piece (the first in the chain) as C1; the pinned piece (second or middle in the chain) as C2; and the target (the third in the chain) as C3. Keep this in mind:

C1 is always Queen, Rook, or Bishop.

Absolute Pins (C3 = K)

Absolute pins, as described above, involve pins where the target is the king. In other words, there is an attacking piece, a pinned piece, and behind the pinned piece is the king.

Let's look at what happens to the to pinned piece:

• Knight (C2: N): If the pinned piece is a knight, the knight loses all of its mobility 100% of the time.  

                    

• Bishop (C2:  B):
• File pin: The bishop loses 100% of its mobility.

                    

• Rank pin: The bishop loses 100% of its mobility.

                    

• Diagonal pin: The bishop can move between C1 (meaning he can capture the attacking piece) and C3 (which would be his own piece). From here on out, I will refer to this as "limited mobility."

                    

• Rook (C2 = R):
• File pin: Limited mobility.

                    

• Rank pin: Limited mobility.

                    

• Diagonal: The rook loses 100% of its mobility. 

                    

•  Queen (C2 = Q): The queen always has limited mobility when it is pinned.                    

                         

• Pawn (C2 = P): 
• File pin: The pawn has limited liability meaning that the pawn can move but cannot capture or promote (either due to C1 or C3). 

                      

• Rank pin: The pawn loses 100% of it mobility.     

                    

• Diagonal pin: The pawn loses 100% of its mobility when it comes to movement but 50% of its capture mobility--the pawn can only capture in the direction of C1 or C3, depending on how the king is pinned. However, it should be pointed out that there is technically no pin when there is a piece between C2 and C3.

                                                                                                                                               
Do absolute pins sound simple enough? Test how well you can see pins with the following problems: 

Puzzle #1: Bronstein - N.N., Moscow 1953
White to play


Puzzles #2: Evans - Bisguier, U.S. Championship 1957
White to play


Puzzle #3: Brundtrup - Budrich, Berlin 1954
White to play (calculate all the way through)

Puzzle #4: Ed. Lasker - Avalla, New York 1947
White to play


Puzzle #5: Kasparov - Browne, Banja Luka 1979
White to play