08 November 2011

The Bridge, the Diversion, and the Best Defense

One of the quirks of blogging is that you don't have to follow an idea from start to finish, in chronological order, whether as writer or reader. Earlier this year I started a series on Levenfish's Rook Endings, the well known endgame book by Levenfish and Smyslov. After a few related posts using tablebases I dropped the topic to move onto other subjects, but recently returned to it for a deeper insight into a couple of Rook & Pawn endings I'm currently playing.

At the end of that initial post I listed the general conclusions from the last chapter of Rook Endings and am just now starting to appreciate how helpful they can be in a practical context. One of the conclusions, however, baffled me...

11. With two disconnected Pawns against one passed Pawn important roles are played by the bridge and diversion.

...because I didn't take the time to study the text of the book:-

In no.11, I'm not sure what is meant by 'bridge and diversion', so I'll come back to this and other points in a future post.

Ten months later, I'm coming back to it. As you would expect, both terms are illustrated in the position accompanying that 11th point.

Levenfish & Smyslov no.314
After 2.e6-e7

The 'bridge' is illustrated in the continuation: 2...Re6 3.Rf7 (bridge) 3...Kb4 4.g4 a3 5.Rf4+ Kb5 6.Rf3 a2 7.Ra3. White uses his own Rook to shield his King from checks by the opponent's Rook. The maneuver is best known in the 'Lucena position', a technical procedure for winning with Rook & Pawn vs. Rook.

The 'diversion' is illustrated in the continuation 2...Rf6+ 3.Ke3 Re6+ 4.Kd3 Rd6+ 5.Kc3 Re6 6.Rg5+ Kb6 7.Rg6 (diversion). White's Rook pins the opponent's Rook against its King, eliminating the attack on the White Pawn and allowing it to promote.

Black avoids both of these attacks by playing 2...Rc8! 3.Rg5+ Kb4 4.Re5 Re8 5.g4 a3. When behind in material, a passed Pawn rushing to promote is the weak side's best defense in Rook endgames. I don't know if this concept also has a term to describe it, but it should.


Later: This post appeared in Happy Birthday, Carnival!, the last of the blog carnivals organized by Confessions of a Chess Novice [chessconfessions.blogspot.com].

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