What is PIN?

Hi guys, 

               Today we are going to talk about what is pin. 

It literally means freezing the pinned chessman as moving it will allow you to capture the more valuable piece behind it. Pin can only be done by Queen, Rook Or Bishop. For pattern recognition, you will find three pieces on the same line after creating a pin. 

Basically, there are two types of pin:

>Absolute Pin:In absolute pin, the chessman of greater value behind the piece is a king. Here, it can't move as it will put the king in check

The second example of pin is from  a very famous miniature game played between GM John Nunn and GM Kiril Georgiev, Linares, 1998.

:The power of absolute pin in a more complex setting is demonstrated in the game between Edward Lasker and Avalla, in 1947.

Seeing that black is lagging behind in development with its king stranded in centre, Lasker played Qa4+.Black's forced reply was Qc6 as Kf8 would have allowed White to force mate in two, starting withBh6+.Black was now praying for exchange of queens but Lasker destroyed this hope with a harsh Rd8+!!. Forcing Kxd8. The queen's defender knight is now pinned., allowing white to win Black's queen. 
It would be more clear by the game between Espig-Knaak from the Eastern German Championship in 1973.

>Relative Pin:When the piece of greater value behind the pinned chessman is not the king, it is called Relative pin. Here the pinned chessman is free to move, at the risk of losing the chessman of greater value. 

The best example of  Relative pin is:The Legal Mate.

Thankyou guys, Hope you liked it. 

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And just write the answer if you know of example 3 if Kf8 and then Bh6+, so how there is mate in one move.