Friday, June 20, 2014

Rook Endings 4: Rook Versus Two Isolated Pawns.

We considered the fascinated case of rook versus two connected pawns in the previous post in our rook endgame series. This time the focus is on the rook versus two isolated pawns ending. Let's get right to it.

Second Case: Rook Versus Two Isolated Pawns.

In most rook versus two isolated pawn positions the side with the pawns is defending. The further separated the pawns the more difficult it is for the player with the pawns. This is illustrated clearly by the fact that pawns separated by four or more files can't defeat a rook on the 8th rank.

Monday, June 16, 2014

Rook Endings 3: Rook Versus Two Connected Pawns.

Endings in which a rook faces two pawns are more common and difficult than rook versus single pawn endings. There are 420 games in my mega database from the beginning of 2013 through mid-June 2014 in which this ending is played for four or more moves. 57 or 13.6% of those 420 games did not reach the result expected by the tablebases (meaning that there was a result-changing error). Some of those errors were, as we shall, by very high rated players.

There are basically two types of rook versus two pawn endings:
  1. Where the pawns are connected.
  2. Where they are isolated.
We will cover the case of connected pawns in this post.

Sunday, June 15, 2014

Rook Endings 2: Rook Versus Pawn Continued

In a prior post we examined the key ideas in rook versus lone pawn endings. In this post we will look at some special and complicated cases of this ending. Specifically, we will be looking at the following:
  1. A non-trivial case where the side with the pawn is winning. 
  2. A case in which the rook is between the pawn and its queening square and the attacking king on the other side of the pawn.
  3. The special case of the rook pawn.

Friday, June 13, 2014

Rook Endings 1: Rook versus Pawn

Rook endings are among the most common endings and playing them well is one of the most important and subtle endgame skills. To improve my chess (and hopefully yours as well) I am beginning a series of blog postings on rook endings. We are going to begin with the most basic rook ending: rook versus a lone pawn. These seemingly simple endings can actually be quite tricky and are mishandled more often then you might expect. Since the beginning of 2012 through mid-May 2014, 523 games in Chessbase's mega database reached a rook versus pawn ending that was played out for four or move moves. 47 or 9.2% of those 523 games did not reach the result expected by the tablebases at the moment the rook versus pawn ending began. To be sure, many of the poorly handled endings were by weak players who made silly mistakes, but not all of them. Even grandmasters erred. Clearly, this endgame is not trivial. Its key ideas need to be mastered. They are the following:

Attacking ideas:

1. Cutting the enemy king off at his fourth rank.
2. Gaining or losing tempi with rook moves.
3. Avoiding stalemate.
4. Getting the king in the game.
5. Moving the king to the side of the pawn opposite the enemy king.

Defending ideas:

1. Shouldering away the enemy king.
2. Promoting to a knight.

Let's look at them one by one, and then we will examine a few cases in which more than one idea is used.

Thursday, June 5, 2014

Mate in 549!

Mate in 549 is the latest discovery of the position-crunching supercomputers that calculate tablebases. Tablebases are databases of chess endings that have calculated the optimal moves until a draw or checkmate results. They can be purchased to put on your personal computer. Chessbase, for example, sells a product called "Endgame Turbo" which gives you the solution to all endings with five or fewer pieces and some endings with six pieces on the board. The data for this comes on nine DVDs and occupy 43 gigabytes on your hard drive when fully installed. That may sound like a lot of memory, but the full six piece endgame tablebase requires 1,200 gigabytes. Don't want to pay or clutter your computer with chess moves? You can also plug positions into online tablebase tools to find the chess truth that you seek.

Recently, seven piece tablebases were calculated by a supercomputer at Moscow State University and occupy 130,000 gigabytes. Among the nuggets of chess knowledge uncovered was that the longest forced mate with seven or fewer piece on the board is in 549 moves. Want to try to solve it? The position is as follows:

White to Mate in 549

Can't visualize it to the end? Give up? The solution is here.

After seeing this, I can't help but conclude that chess will never be solved. No computer will every play it perfectly, and the royal game will never be exhausted.

Monday, June 2, 2014

Beating Inferior Openings: Meeting 4.Bc4 in the Four Knights (part II).

In the first part the Four Knights after 4.Bc4 Nxe4 5.Bxf7+ was analyzed. In all lines black is much better. The lines analyzed here start with 4.Bc4 Nxe4 5.Nxe4 d5 (fig 1), which forks white's pieces, regaining the lost material.

Fig 1. Position after 4.Bc4 Nxe4 5.Nxe4 d5.
What is the best way for white to give back the material?

In this position, white has a number of options, only one of which does not hand the opening advantage to black. The main moves are 6. Bxd5, 6.Bb5?, and 6.Bd3. Other moves are, of course, possible, but these are the most commonly played ones. Let's consider each of them.