Friday, February 7, 2014

Chess960: The Bishop Sweet Spot

Here is the start of series of posts on what I call "the bishop sweet spots" on the chessboard, which are squares that allow the bishops to come out and be active, yet avoid being exchanged off. Usually in the opening we are trying to avoid changing the strategic quality of a position by exchanging a bishop for knight before the opening has had a chance to evolve (the bishop might be needed). The bishop sweet spots are not really outposts, because they are not solid enough to be called an outpost. They are just important squares in the Chess960 opening system, that need to be considered.
From classic standard chess (SP518), a very well loved and well worn bishop sweet spot is on b5 and it's mirror on g5. As we all know, the knight gets pinned and the bishop can sit on it's sweet spot for a long time, creating some important thematic tactics:

The Classical Queenside Bishop Sweet Spot (b5)

Finding the sweet spot is really easy. Look for any SP where a bishop and knight are separated by a minimum of three squares, triangulate vertically, and the bishop sweet spot will be three ranks directly above the knight.
Triangulating to find the Bishop Sweet Spot

In summary, the general definition of the bishop sweet spot is:
Classic Bishop Sweet Spot:
  1. The start does not contain Military Knights
  2. Bishop and knight separated by at least three squares
So, what are the benefits of the bishop sweet spot?
  1. The sweet spot square allows a bishop to sit without being attacked by another knight
  2. A bishop on a sweet spot does not have to waste tempo relocating
  3. Since the bishop is actively placed, it can create tactics striking the enemies back row
  4. Finding a safe square to place pieces helps with rapid, coordinated development
  5. Gives the bishop a chance to transition to a different diagonal
  6. If the enemy tries to kick the bishop off the sweet spot, this can be at the expense of pawn structure
Here is a start that fails the bishop sweet spot test:
Military Knights mean the sweet spot can be attacked
Here are some examples of the many bishop sweet spots in Chess960!
SP007 - Classic Bishop Sweet Spot

Notice that when the bishop is in the corner, the bishop on its sweet spot (d5), attacks the position of blacks castled king (g8).
Variants of the classic bishop sweet spot:
Chivalry Knight Sweet Spot:
  1. The start contains Chivalry Knights
  2. There is still a space of three squares between bishop and furthest knight
SP007 - Chivalry Knight bishop sweet spot
Even when the chivalry knight sits in the middle, the bishop sweet spot can still not be attacked by an enemy knight.
Variants of the classic bishop sweet spot:
Monastic Knight Sweet Spot:
  1. The start contains Monastic Knights
  2. There is still a space of three squares between bishop and furthest knight
SP114 - Monastic Knight bishop sweet spot

Notice that the monastic knight variant is not as tactically strong as the classic bishop sweet spot because the bishop only ever hits a knight on the enemies back rank. However, the sweet spot might still be useful to use as a spot to temporarily locate a bishop to aid in rapid, coordinated development.
Finally, don't forget that the mirror version of the bishop sweet spot also exists and is just as powerful.
SP001 - The bishop sweet spot reflected on the queenside

Finally here is a sample game that demonstrates the bishop sweet spot quite nicely:
SP511 - White finds the bishop sweet spot!
White finds the c5 square to pin black's knight against the rook
Enjoy 960

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