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Game analysis with Chess Assistant 10 02 September 2008

Buy Chess Assistant 10 In the two previous columns we examined infinite analysis with Chess Assistant 10. Infinite analysis is a very useful tool, but it is best suited for analysis of a limited number of positions. One of the drawbacks of infinite analysis is that as soon as you want to examine more than one position it turns into a manual process where you have to make the decision when a position has been analyzed deeply enough and then manually move on to the next position and so on. For the improving player it is more efficient and useful to have all phases and every move of the game analyzed automatically. Each tournament game you play should be subjected to such analysis and stored for future reference after trying to learn as much as possible from the game and its analysis. Just remember that engine analysis is not a replacement for your own analysis. Always start by entering your own thoughts about the game and only then analyze it with Chess Assistant.

Part One

Chess Assistant 10 offers a wide selection of methods for automatic analysis of complete games. This month we will examine one of them, which is simply called “Game analysis”. “Game analysis” is simple enough to be used by a beginner and at the same time offers all the fine tuning that an advanced user might need. It even allows you to select different chess engines, time settings and analysis methods for each phase of a game (opening, middlegame, endgame).

“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. This is the simplest way of using “Game analysis” and the one I would recommend to beginners. We’ll be discussing this method below.
  • Select method using levels. This method gives you access to settings that allow you to control the analysis down to the smallest details. Fortunately the user interface to all this power is designed so that even a near beginner can take advantage of this method.

Select Method Using Time

Even beginners can get impressive results from “Game analysis” by using “Select method using time”. This method doesn’t require understanding of the underlying algorithms and is reached as shown in the image above. The following dialog box is then displayed.
This screen contains everything that is needed to start “Game analysis” and, based on your choices, shows what methods of analysis will be used (red letters) for each phase of the game. Getting a full game analysis can be as simple as choosing how much time should be allocated and clicking OK. Chess Assistant 10 will take care of the rest. Let’s go through the options that are available on this screen.

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.

Player statistics

During opening analysis Chess Assistant searches the database for games played by the two players in the same opening as in the game being analyzed. The results are added as commentary to the game as shown here.

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.

Verbal commentary
Chess Assistant can add verbal commentary to moves and positions in the game. The commentary is based on the Chess Opening Encyclopedia, which is included with Chess Assistant 10. The screenshot shows an example from the Paulsen variation of the Sicilian defense.
As you can guess by reading this text it is not computer generated, but was prepared by the Russian grandmaster and opening expert Alexander Kalinin. His opening explanations can be very helpful for new and improving players. Note that not every opening line will be annotated with such commentary.

Reference games
Chess Assistant 10 searches its extensive database, appropriately called HugeBase, for games that are relevant for the opening played in the game and inserts fragments from them as annotations. The screenshot shows three game fragments that have been inserted at different points in the opening. You will probably notice that two of the fragments are from games of the players who actually played the game that is being annotated. This preference for games by the players themselves is a very nice feature, but of course Chess Assistant also uses reference games from other players as can be seen after the move 7…b5. There you see a game between Vladimir Kramnik and Josif Dorfman from the French Team Championship in 2003. The game fragment shows that instead of 7…b5, Dorfman chose the move 7…d6. Then we are shown the moves of that game up to White’s 17. a3. This move is followed by “… 1/2-1/2”. The ellipses tell us that the game did not end at this point, but we also see that eventually the game ended in a draw.
Evaluations from Chess Openings

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 evaluations

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.

Opening novelty
All chess players are interested in opening novelties and Chess Assistant will find them automatically for you during game analysis.
This screenshot shows a game fragment where White played an opening novelty on move 13. The novelty is marked with an ‘N’ as is customary.

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.

Chess engine evaluations
Chess Assistant needs only a few seconds to perform the analysis described above, but now we come to the part where most of the analysis time is spent. This is where the chess engine analyzes the moves of the game looking for mistakes and suggesting improvements. The screenshot shows an example of the results of analysis by Shredder 9.11.

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:

  • Player statistics
  • Verbal commentary
  • Reference games
  • Evaluations from Chess Openings 2007
  • CAP evaluations
  • Opening novelty
  • Chess engine evaluations

Next month we will continue the discussion of game analysis in Chess Assistant and look at some slightly more advanced methods.

Part Two

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).

In fact, advanced users can tune the analysis algorithm almost any way they like, by choosing the right settings. The key to this flexibility is “Select method using levels” which is on the “Engines” menu under “Game analysis” as shown on the screenshot.
“Select method using levels” displays the following dialog box.

This dialog box contains three group boxes, one for each phase of the game; opening, middlegame and endgame. Each group box contains a slider, currently set at its default position which is indicated in the label of the box (e.g. Opening:3). Each slider can be set to eight different positions (0-7). Setting a slider to the leftmost position (0) skips all analysis for that phase.
Moving it to the right will give more detailed and accurate analysis. The red text to the right of the slider describes the type of analysis that will be performed at the current setting, and it is updated interactively as the slider is moved.
One ChessOK column cannot describe all the possibilities offered by this analysis method, but in the following some of the more important options are summarized.

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 Opening

The following three methods are only available for the opening stage of a game:

  • Search for novelty. The move where the current game deviates from known games is noted. Moves that have previously been played in that position are shown and relevant games are referenced.
  • Annotate opening. The program will annotate the opening based on GM Kalinin’s analysis in Chess Openings 2007 and data from Convekta’s CAP analysis.
  • Insert reference games. Games that are valuable for the particular opening variation played in the game are inserted as comments.
By default opening analysis applies all three methods described above as shown in the screenshot.
The Middlegame

Middlegame analysis allows you to use CAP analysis for annotating the game. CAP is turned off by default, but you can activate it by clicking the “Use CAP” checkbox shown on the image.

For further information about the CAP project see last month’s column.

The Endgame
For the endgame analysis you can decide if so-called tablebases are used or not. Tablebases are endgame databases that store all positions with a given material balance and their results.

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.

  • Search for blunders. This is the good old blunder check, although I have more or less abandoned this method in favor of the more advanced methods described below. It will not be discussed further in this article.
  • Quick analysis. The method should be used for a quick analysis of the game (perhaps 1 second per move). The idea is to get a bird’s eye view of how the game developed. This analysis may show that the result of the game was already clear long before the game ended. In that case the final stage of the game will not be analyzed further.
  • Main analysis. This is usually the most time-consuming step in the analysis. The chess engine analyzes the moves of the game and suggests improvements. The following analysis methods concentrate on the improvements suggested in this step and no more time is spent on analyzing moves in the game where improvements are not likely to be found.
  • Checking. The chess engine checks all improvements it has found in “Main analysis.” Since it only checks the suggested improvements and not all moves in the game more time can be allocated to analyzing each position. Just like a human taking a closer look at a position, the chess engine may “change its mind” at this stage and reject earlier suggestions for improvement.
  • Prolong lines (autoplay). The chess engine analyzes the variations deeper and extends them by the number of plies (half-moves) specified by the user.
  • Alternative moves. Instead of accepting the suggested improvement you can force the engine to analyze other possibilities by using this method. When a chess engine is forced to ignore a particular move and examine others it may lead to a change in its evaluation and a replacement of the suggested improvement.

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 easiest way to tune the analysis options for each phase of the game is by using the sliders that were discussed above and shown on this screenshot. When you move the sliders the red text shows which analysis methods will be applied, and how much time (in seconds) will be allocated to analyzing each position.
In this example no engine analysis will be performed in the opening phase of the game, although it will be annotated by looking up information in HugeBase and annotations in opening trees. Engine analysis based on “Quick analysis”, “Main analysis” and “Checking” will be applied to both the middlegame and the endgame.

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.

We are looking at the “Multi-pass analysis” tab, which looks exactly the same for the opening and the endgame, too. The five analysis methods discussed above are listed down the left-hand side with a checkbox in front of each allowing you to enable or disable individual methods.
In the “Engine” column you can choose the chess engine that you think is best for each task. One idea is to use a different engine for generating alternative moves, getting a “second opinion” of the analysis. You can also choose one engine to do all the middlegame analysis and another one for endgame analysis.
The “Time” column shows the number of seconds that the engine should use for analyzing each position. In this example each position will be analyzed for 2 seconds in “Quick analysis”, for 30 seconds in “Main analysis” and for 60 seconds in “Checking”.

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.

Near the bottom of the dialog box you can select for which side moves are analyzed. The default is to analyze moves for both sides, but this screenshot shows the available options.

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”.

What do the “!” and “?” symbols mean?
These two common chess symbols, the exclamation mark ! and the question mark ?, are normally bestowed in an arbitrary way in game annotations. You will find books where they are lavishly scattered throughout the games while in other cases they are used very sparingly. Chess Assistant “Game analysis” allows you to use these symbols consistently throughout the analysis, but you can adapt their usage to your own personal preferences using the dialog box shown on this screenshot.

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.

Dadi Jonsson

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