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Game analysis with Chess Assistant 10 02 September 2008
“Game analysis” is on the “Engines” menu as shown in the screenshot.
We are interested in the two items at the top of the submenu under “Game analysis”:
Select Method Using Time
Time. The “Time” panel has seven predefined time intervals, ranging from 1 minute and up to 12 hours. This defines how much time Chess Assistant 10 should spend on analyzing a single game. I have set this parameter to 16 min. - 1 hour. You may wonder why the time is specified as an interval and not a fixed number. The reason is that the same depth of analysis for two separate games may require widely different lengths of time. Even games with the same number of moves can be very different in this respect and there is no way to calculate beforehand exactly how long the analysis will take. Therefore, it can even happen that the analysis for some games will exceed the upper bound of the specified interval. When deciding how much time is spent on the analysis, remember that longer is always better. This gives the chess engine time to analyze the game more deeply and returns more reliable results. For analysis of tournament games I recommend at least 1-3 hours.
Time (%). This parameter acts as a percentage multiplier for the interval selected in the “Time” panel. In the screenshot above it is set to 100% which means that the “Time” interval is not affected and you can expect the analysis of a game to take the time specified there (16. minutes – 1 hour in this case). If I change the percentage to 200% the time would be doubled (32 min.- 2 hours) and if I set it to 50% the time would be halved (8 min. - 30 min.). So, by combining “Time” and “Time (%)”, you have great flexibility in choosing a time schedule for the analysis.
Engine. You can choose any of the installed engines for the analysis. The screenshot shows that I have selected Shredder 9.11, which is one of the standard engines in Chess Assistant.
Insert annotations from tree. Opening trees in Chess Assistant can contain verbal comments. This feature is used extensively in Rybka and Chess Openings. When you select “Insert annotations from tree”, as I have done in the screenshot, Chess Assistant will insert commentary from the tree into the game annotations. We’ll see an example later in this article.
After selecting the time taken to analyze the game and setting other parameters just click OK and Chess Assistant will start its analysis.
The Results of “Game analysis”
The results from “Game analysis”, both “Select method using time” and the more powerful “Select method using levels” contain the same elements, so the following description of the analysis results applies to both methods.
The first line tells us that the opening of the game is the Paulsen variation of the Sicilian defense, which is identified by the ECO opening code B43. The ECO opening codes are a widely used system of chess opening classification using the codes A00-E99. The next line shows that Jon Viktor Gunnarsson had the white pieces in this game. Chess Assistant found 10 games in its database where he played this opening. He won 3 games, drew 5 and lost 2. The last line shows similar information about Aloyzas Kveinys who had the black pieces in this game. The three capital letters in parenthesis after each player’s name is his country’s abbreviation. The county codes are the same as those used in the FIDE rating list.
Besides the commentary discussed above, Chess Assistant also uses grandmaster evaluations from Chess Openings 2007 for annotating the opening. The evaluations are in the customary Informant style. An example can be seen in the screenshot above after 7.f4 where, according to GM Kalinin, White has a minimal advantage.
CAP is short for the Computer Analysis Project, an effort started by Dann Corbit. CAP has been run as a distributed computing project by Convekta for several years with the participation of volunteers. Tens of millions of positions have been evaluated and Chess Assistant comes with a large database of such precomputed positions. Chess Assistant can take advantage of this treasure of evaluated positions during game analysis and insert CAP evaluations at selected points in the game. As you can see in the image, these are presented as numeric evaluations (centipawns), although there is an option in Chess Assistant that allows you to display Informant symbols instead. Positive numbers mean a White advantage and vice versa for negative numbers. In this case the CAP evaluation of the position after 9.g4 is -0.22. All evaluations from the CAP database are followed by the text ‘CAP’ so they will not be confused with evaluations computed by the chess engine during game analysis.
Since this move is a novelty it means that one or more games have been played with a different move in this position. Chess Assistant will find those games for you in the database and insert them as reference games after the novelty. In this case Chess Assistant tries to give an overview of other moves tried in this position and may insert several games by players of varying ability. The reason is that some of the alternatives have only been played by non-masters. In other cases reference games are limited to games played by higher rated players.
Let’s first look at White’s 15th move, 15.cxd3. Shredder’s evaluation of the position after this move is +0.22, which means that it is almost even and just slightly in White’s favor. Chess Assistant sees, however, that this was a dubious move and White could have played a better move. As a result the move 15.cxd3 gets the “dubious move” symbol “?!”. Shredder’s suggested variation is displayed in square brackets after the move. It starts with the move 15.Rxd3 which is decorated with “!?”, meaning a move deserving attention. At the end of the variation we see Shredder’s evaluation, +0.85, which is quite a bit higher than the evaluation of the move actually played. We see another suggestion from Shredder after Black’s 15…f6. In this case the move is clearly a blunder as White’s advantage increases to +1.33 instead of staying at +0.22 had Black played the move 15…d4 as suggested by Shredder. Note the sign in front of the first move in the variation suggested by Shredder. It stands for “better is” and is yet another Informant sign commonly used when annotating games.
As we have seen in this article full game analysis can be quite simple in Chess Assistant 10. By using the “Select method using time” of the “Game analysis” function, users only have to choose the time allowed for the analysis and click the OK button. As a result Chess Assistant will produce the following analysis of the game:
Next month we will continue the discussion of game analysis in Chess Assistant and look at some slightly more advanced methods.
This month we continue the examination of the “Game analysis” function in Chess Assistant 10. Last month we saw how easily even a beginner can perform advanced game analysis and the wealth of useful information that such analysis returns. The average user will normally settle for the default parameters, and only change the time setting and perhaps the analysis engine. But as was mentioned last month, one can also fine tune the analysis by selecting different chess engines, time settings and analysis methods for each phase of a game (opening, middlegame, and endgame).
We start by describing options that are specific to each phase of the game and then we examine analysis methods that are available for all three phases.
The following three methods are only available for the opening stage of a game:
For further information about the CAP project see last month’s column.
For example, there is a tablebase file (normally named something like KQK) that covers positions where one side has a king and queen, while the other side has a lone king. If such a position arises in a game (or somewhere in the analysis) Chess Assistant 10 will consult the tablebases and immediately know what the result would be with best play. Tablebases for positions with 3, 4 and 5 pieces (including the kings) are commonly used, but 6-piece tablebases are also available now. The construction of endgame databases was pioneered by Ken Thompson, but these days the tablebase format designed by Eugene Nalimov is the most common. Chess Assistant 10 Mega Package comes with a DVD with Nalimov endgame tablebases (all 3-4-5 pieces) and 2 DVDs with selected 6-piece tablebases. They can also be bought separately or even downloaded from the Internet, although their size may not make it an attractive option for some users. Provided that you have installed the tablebases you can select the option “Use tablebases” in the Endgame group box shown on the image.
Options available for all phases
In addition to the specific analysis methods for each of the three stages of the game, there are 6 methods that are available for all three stages.
If you look at the last 5 analysis methods in the bullet list you will see that the methods used by Chess Assistant are quite similar to those that might be used by a human player manually analyzing and annotating his games.
Setting the analysis options
The only difference is that “Checking” will use 60 seconds for each position in the middlegame and half that time in the endgame. In addition “Prolong lines” will be applied to the middlegame.
So far we have seen two ways to choose the time and analysis methods used for analyzing games, starting with last month’s discussion of simply choosing the duration of the analysis and letting Chess Assistant automatically choose the analysis methods based on that. The sliders offer you more control, but if you really want to take things into your own hands, click one of the “Advanced…” buttons. The next image shows what the “Analysis properties” dialog box looks like for the middlegame.
There is one more parameter that you can set for the “Checking” method. In this example it will not analyze moves where the evaluation of the suggested improvement differs less than 30 centipawns from the evaluation of the move played. You can, of course, set this parameter to any value you like. Setting it to zero will let the engine check all the improvements suggested by “Main analysis”.
“Prolong lines” has the additional parameters “Half-moves” and “Positions”. Using them you can define how many half-moves the suggested variation is extended and the total number of positions analyzed by this method.
“Alternative moves” allow you to set the number of alternative moves (”Moves”) that are generated and a limit (”Delta”) similar to the one in the “Checking” method.
Finally, you have the option to decide what constitutes a decisive advantage (”Decisive advantage value (centipawns)”). On the “Analysis properties” screenshot above it is set to 200, meaning that a 2 pawn advantage is considered decisive which is a bit on the low side. I often set it to 300 or even 400. The only downside to a higher value is that the analysis will take slightly longer time as this is the cut-off value used in “Quick analysis”.
To reach this function click the “Commenting options” button on the “Select method using levels” dialog box (shown on the second screenshot in this article).
The Excel-like table in this dialog box defines how the exclamation and question marks are awarded. Suppose you want to adjust how the engine determines when it has found a blunder (see the second line from the bottom in the table on the screenshot). Currently, if the difference in the engine’s evaluation of the position is between 1.01 pawns and 3 pawns, then the move suggested by the engine will be awarded a question mark. If you want to change that the lower limit to say 0.81 pawns, just modify the value in the “>=” column. Remember that for consistency you should also change the “< " column in the "Dubious (?!)" line to 0.8.
This concludes the discussion of “Game analysis” in Chess Assistant. Some of the analysis options have been described in detail while we have barely touched upon others. Still, it should be clear from last month’s column that this powerful function is easily used even by beginners. This month’s column shows how advanced users can fine tune the analysis methods.
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