Posts Tagged: analysis

Thinking Process / analysis / calculation — 1 Comment
15
Aug 10

Think Like a Chess Engine

In Kotov’s great book “Think Like a Grandmaster” he taught the average chess player the inner workings of how a chess master thinks about a position by creating a tree of candidates and then proceeding along the tree. While there is much to learn from Kotov’s work, I have always been facinated how computers can evaluate positions and how their positional play is derived from these material evaluation algorithms. I believe that the way chess engines derive material evaluations might help the lower rated amateur improve their evaluation skills.

Below is a combination of the Crafty chess engine algorithms as well as Larry Kaufman’s material evaluation processes which is used by the Rybka engine.

Pawns

Pawn = 1

isolated pawn penalty based on file:
a-pawn : -.12
b-pawn : -.14
c-pawn : -.16
d-pawn : -.20
e-pawn : -.20
f-pawn : -.16
g-pawn : -.14
h-pawn : -.12

Doubled pawn (and not also isolated) penalty of -.12 plus add isolated pawn penalty

Backward pawns -.06 penalty +.04 bonus for attack on backward pawn on semi-open file.

Pawn advance in center +.04 / rank increasing to about +.08 / rank in the endgame
Development

Rook pawn is worth 15% less than a regular pawn (.85 of a pawn) (L.Kaufman)

Knights

Knights = 3.25
Centralized knight: +.30
In outpost : +.08

Unpaired knight is worth approximately 3.14 pawns (worth less) (L.Kaufman)

Bishops

Bishops = 3.25
Bishop in endgame +.10
Bad bishop : -.04
Corner bishop : 0.0
Center bishop: +.3
Attacking / good bishop: +.18
Attack against King: +.05

The Bishop Pair

Bishop pair: +.50  Bishop pair is worth .50 more if not pieces exist to exchange them (L.Kaufman)

Bishop pair is worth less than .50 a pawn when most or all of the pawns are on the board, and more than .50 pawns when half or more of the pawns are gone (L.Kaufman)

If you have the bishop pair, and your opponent’s single bishop is a bad bishop (hemmed in by his own pawns), you already have full compensation for 1 pawn (L.Kaufman)

Unpaired bishop is worth approximately 3.14 pawns (worth less) (L.Kaufman)

Rooks

Rooks = 5
Attacking on open-file: +.20
One semi-open file: +.10
On open-file: +.14

Rook and Bishop is better than the Rook and Knight. (L.Kaufman)

Queen

Queen = 9.75

Queen and Knight is slightly better than Queen and Bishop

King
Centralized in opening: -.24
Centralized in endgame: +.36
On open file in opening: -.23
No adjacent pawns: -.08

Special Cases

Hanging pieces: -.10

Exchanges favor the side with a material advantage

Minor pieces lose their value as the endgame approaches

In endgames with no other piece the bishop is worth about 2.5 and the knight 2.25 with other pieces the minors are worth about 3.25

Rooks gain value as the endgame approaches

Note: I have modified the Crafty point values to reflect the Kaufman values.

Resources

Evaluation of Material Imbalances in Chess

GNU Chess Positional Heuristics

http://chessprogramming.wikispaces.com/Evaluation

http://www.chessvariants.com/d.betza/pieceval/index.html

Chess / Chess Puzzles / Improvement / Tactics / Thinking Process / analysis / calculation — 3 Comments
6
Jun 10

Connecting the Dots in Chess

I have made an observation while solving puzzles, that I feel will improve my tactical puzzle solving skills, and might have direct application during actual games.

When solving a tactical puzzle of intermediate to advanced level I either:

1. Have no clue how to go about solving it and get it wrong.

2. Have multiple ideas that look promising, but after further analysis don’t win {usually end up playing one of the two and get the answer wrong}.

3. Solve the puzzle correctly.

This post is going to focus on solving the 2nd category above. I have found that you will get many more puzzles correct by combining ideas that arise by analyzing different candidate moves. Unfortunately, by not making a link between the two, or forgetting about your first idea when looking at the second, I mainly fail to connect the dots and only after reviewing the correct answer do I see that I had been on the right track and would have answered correctly  if I had combined my candidates.

You might want to solve this puzzles on your own before reading the answers below taking into account your thought process while doing so and then see if you encountered the same issues as I did.

Here’s the first position we will look at:


White to move and win

The first candidate that came to mind was 1.Bb6 attacking the Queen. I analyzed the response 1…Nxb6 2.axb6 Qxb6 which loses a pawn for White and the Black Queen lives on. So I abandoned this candidate and looked for a better move.

I then found that Qh6 looked promising and I began to analyze 1.Bh5 with the idea of Bh8 and then getting my Queen to h6. But I soon found that 1.Bh5 was a slow since it allows 1…Kh7 and White is out of gas. What I missed, and where I think there is room for improvement, is if I would have combined both moves. Attacking the Black Queen with 1.Bb6 with the idea of freeing the diagonal for my Queen to get to h6 with mate was the winning combination and one I failed to see by not connecting the dots.

Let’s look at another example, and one which occurred right after I had attempted to solve example #1 above.

White to move and win

In this position quickly saw that both the White rook and Queen were attacking the Black d8 rook, and that there might be a tactical opportunity if the Queen were deflected from its defense. The candidate that came to mind was 1. b4 but after further analysis I saw that the Queen could seek shelter by moving to 1…Qc7.  The other candidate that stood out was 1.Qf6+ but the King can easily get out of the way with 1…Kg8 and there aren’t enough White pieces in the vicinity to force the issue. The third candidate I analyzed was attacking the undefended bishop with 1.Qe7 but I found that the bishop can get out of harms way via 1…Bc8. If I would have combined the two ideas or even looked a few ply deeper  I would have found the answer 1.Qe7 attacking the bishop and preventing the Queen from seeking shelter at c7 after deflecting her with b4. 1…Bc8 2.b4! and Black resigned.

Thinking Process / analysis — No Comments
1
Jun 10

Critical Moments in Chess

GM Dorfman, has suggested that every game has 5 or 6 critical junctures “forks” at which important decisions need to be made. By understanding that the game has reached a critical moment, you can take extra time in analyzing and evaluating your moves. These critical moments are where games are won or lost, and identifying these milestones in a game are the key to improving your game. Critical moments are characterized by the presence of 2 to 4 different possibilities. Below is Dorfman’s list of critical moments:

Critical Moments (Dorfman)

  • Positions where there are possible exchanges.
  • Change in pawn structure (especially central pawns).
  • At the end of a  series of forced moves (combination).
  • Transposition into an endgame.
Annotated Games / Training / analysis — 2 Comments
21
Jan 10

Analyzing Your Games

According to Mark Dvoretsky the analysis of one’s own games is the main means of self-improvement.  In Secrets of Chess Training Dvoretsky offers the following guidelines:

  1. Find the turning points – Decide where mistakes were made, where the evaluation of the position changed or an opportunity was missed.
  2. Seek the reasons for your own mistakes – The objective realization of your own weaknesses is a necessary first step in the work of correcting them.
  3. Seek new possibilities, which you did not notice during the game.
  4. Ponder over the opening stage – Approach the problems you faced during the opening to increase your knowledge and outline new plans.
Chess / Improvement / Training — No Comments
31
May 08

Developing Chess Skill

According to Johnathan Rowson in his book Chess for Zebras we can develop chess skill through a combination of playing combined with chess training, where ‘training’ means working things out by ourselves. The main skill a chess player needs is skill in making decisions so making decisions is what you need to do over and over when training (learning by doing).

The best training is the kind that pushes you up against the edges of your comfort zone, where you force yourself to take responsibility for difficult decisions.

- Johnathan Rowson in Chess for Zebras

So here’s what you can do to put his advice into practice:

  • Playing and then analyzing your games afterwards
  • Solving complex chess problems
  • Trying to win won positions against strong analysis engines
  • Blitz games (comparing your first impression of positions with the way they actually developed)
Chess / Thinking Process / analysis — No Comments
24
May 08

Analysis Exercise #1


Black to move (Stefanova – Shirov 2005)
r3rq1k/8/p2p3p/P1pPnp1P/1p3Q2/5PNR/1PP2K2/R7 b – - 0 29
Download game

Evaluation
The first thing I did was to evaluate this position, and I gave it the following evaluation: Material =, King Safety +/=, Activity =/+, Pawn Structure =. So the game in my opinon is even. (When I gave it to Fritz 10 he sees it as -+ (- 1.61 with Black winning) and Rybka sees it as -1.19).

Threats and Opportunities
I then looked for threats and opportunities in this position, and I found that White was threatening to win Black’s f5 pawn with Qxf5.

Candidate Move Selection
After performing the threat analysis I looked for candidate moves, and this is the order in which I found my 4 candidates: 1…Re7, 1…Kh7, 1…b3, 1…Ng4+. The first two candidates are defensive, trying to deal with the potential threat of Qxf5, and the last two are aggressive candidates.

Analysis
I then began analyzing the most aggressive candidate based on CCT (checks, captures and threats), in this case …Ng4 would be the most aggressive since it starts with check, below is my analysis:

Candidate 1 …Ng4+

29…Ng4+ 30.fxg4 30…fxg4 31.Qxf8+ Rxf8+ 32.Kg2 gxh3+ 33.Kxh3 This line is good for black since he wins the exchange, so taking with 2.cxb3 is not good for White so I analyzed another line in which White does not take to see if …Ng4+ stands up. [30.Kg2 Not taking keeps White in the game. 30...Ne5 coming back to the same position is not good for Black, since White's King is now safer on g2. At this point I figured that if White didn't take I would wind up in this position, and I stoped analyzing this line, and I jumped to the ...b3 line which was the 2nd most aggressive candidate I had selected. The problem is that 30...Ne3+ should have been considered as a mainline, and I did not see this knight check, with the rook defending it. (30...Ne3+ I did not analyze this subvariation, but it was much better than 30...Ne5 which I did analyze and caused me to jump to another line. 31.Kh1 Nxc2 32.Rc1 Nd4 Black wins a pawn, and defends g5.) ; Rybka 2.3.1 32-bit : 30.Kg1 Ne3 31.Re1 Nxd5 32.Rxe8 Nxf4 33.Rxf8+ Rxf8 34.Rh2 d5 35.Kf2 Kg7 -0.91/12 ]

Candidate # 2 …b3

[29...b3 This is the second line I analyzed. 30.Qxf5 So, I analyzed another line other than 30. cxb3, the problem is that this line is not the best line for White. (30.cxb3 Nd3+ Taking my b3 pawn is bad because of this fork.) 30...Qxf5 31.Nxf5 bxc2 32.Rc1 (32.Ne3 Nd3+ At this point I decided to chose this line.) 32...Nd3+ ; Rybka 2.3.1 32-bit : 29...b3 30.Qd2 bxc2 31.Qxc2 Ng4+ 32.Kg1 Ne3 33.Qd2 f4 34.Ne4 Re5 -1.27/11 ]

Lessons Learned
My evaluation was off by a pawn, Rybka and Fritz think that Black is at least ahead one pawn, while I thought the position was even, so I need to work on my evaluation skills. I was happy with my candidate move selection, and the order in which I began analyzing (the most aggressive moves first). Out of the 4 candidates I only had to analyze 2 and both were the best moves. In the analysis department, I am missing the best response when I calculate variations or I am not analyzing all possible oppnent candidate moves. I need to use the same candidate move criteria fwhen looking for or my opponent responses, but I have a feeling it also has to do with board visualization. Even though I picked an appropriate candidate, the logic for selecting it was flawed and incomplete. The analysis for …b3 did not take into account White’s best responses and much was left to chance by selecting it. I need to be more thorough when analyzing and I also have to attempt to evaluate the position at the end of the my analysis (which I did not do). The line played in the game was …Ng4+!, while Fritz 10 and Rybka prefer …b3.

Chess / Thinking Process — 2 Comments
13
Mar 08

Faulty Thought Process: Wishful Thinking

A frequent issue confronted by amateurs is wishful thinking when calculating combinations. This propensity to fabricate beneficial scenarios in our analysis is very typical throughout an amateur’s game, but it is most dangerous when calculating combinations.

You see a pretty combination worthy of Tal, and you analyze it over and over, after you have finished your analysis you are sure that the move is a winner. You make the move and you lose a piece, or it initiates a series of exchanges that cause you to lose your initiative and perhaps the game. Unfortunately, you have failed to see the refutation or you simply missed a defending piece that you have conveniently kept out of your analysis. This very common oversight causes you to lose material and / or the game.

If only you had realized that there was a defending piece all you usually need to do is to combine that information along with the combinational theme to make the winning move. In most cases by adding the bothersome piece to your analysis you can easily spot a sacrifice or deflection that will get the piece out of the way and lead to a winning combination.

Getting rid of this faulty thought process will lead to more accurate analysis and an improved ability to calculate. Here are a few ways you can improve by eliminating this error in your thinking process:

  • Play long games with a standard time control greater than 30 minutes
  • Pick interesting middlegame positions and spend > 15 minutes analyzing
  • Try to visualize the position before making your move
  • Double and triple check your analysis