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Infinite Analysis with Chess Assistant 10 12 August 2008

Buy Chess Assistant 10 Chess Assistant 10 is a fast and powerful chess database that is equipped with an array of tools to assist active and improving players.
This month I’ll look at some of the methods offered by Chess Assistant for infinite analysis and examine two of them in detail.
Many readers probably think of infinite analysis as pushing a button and watching a chess engine search for the best line of play, but as you will see Chess Assistant has taken this simple concept and turned it into a powerful tool for analyzing and understanding a position.

Part One

As noted last month, infinite analysis means that the chess engine will analyze the current position until you direct it to stop; however, this definition barely touches the surface of the available options in Chess Assistant 10. To access these options, click on the arrow to the right of the infinite analysis button:

Some of these same options were discussed last month; here we’ll take a closer look at the “Infinite analysis…” option. It displays the “Start analysis” dialog box:

As you can see, even for this most basic type of analysis, there is an amazing choice of options. If you just press the OK button without changing any of the parameters, you will get the usual kind of infinite analysis, where a single engine analyzes all the legal moves available. I will not describe every parameter displayed on this screen, but hopefully enough to get you started to experiment on your own.
The drop-down list at the top (“Scheme”) is a shortcut for selecting the most common analysis options. This is a good way to experiment with the different types of analysis. Of course, you can also change the options manually and try out your own ideas.
The options are divided into two panels, “Panel 1” at the top and “Panel 2” at the bottom.

The second panel is used for advanced analysis with more than one chess engine analyzing the position. It can be turned on manually by selecting “Panel 2 is on for analysis”.

The “Type of analysis” radio buttons in “Panel 1” offer normal infinite analysis (“Chronological”), two types of multi-variation analysis ( “Multivariation (1 panel)” and “Multivariation (2 panels)” ) and finally allows analysis using any number of chess engines simultaneously (“Several engines”). Note that this allows you to analyze with more than two engines at the same time.

The “Ignore moves” radio buttons allows you to let the chess engine examine all possible moves (“Consider all moves”) or select moves based on their existence in an opening database or “tree” (“Ignore moves in tree panel” and “Consider moves only in tree panel”). This can be useful, for instance, when you are analyzing a well-known opening, but you want to analyze unexplored moves for a novelty to spring on your opponent.

The “Engine” parameter in the “Parameter” box allows you to select one of the installed chess engines for analysis. Note that Chess Assistant supports many types of chess engines (UCI, WinBoard etc.), so there are literally hundreds of chess engines to choose from. Of course, Rybka can be used, but it must be purchased separately. Here, I have selected Shredder 9.11, an excellent engine that is included with Chess Assistant 10.

Only Analyze Interesting Moves

Many times you may only be interested in analyzing particular moves rather than all the legal moves in a position. In that case Chess Assistant allows you to click on the “Select moves to be analyzed” button in the “Parameter” box to bring up the following screen:

It is White’s move, as indicated by the white triangle below the diagram, and the 53 legal moves in this position are listed to the right of the diagram. However, I’m only interested in two of them: either the straightforward Bxf8 or the more daring Rxh7. The ability to analyze just two moves, instead of all 53, will clearly save plenty of time. In order to select the two moves I wish to analyze, I first clicked “Exclude all moves” and then I clicked the two moves in the list. The analysis starts when the OK button is pressed.

Understanding Threats

Next let’s look at an analysis scheme that can show what is happening beneath the surface in a game and take the mystery out of moves that would otherwise be difficult to understand. From the drop-down list (“Scheme”) at the top of the “Start analysis” dialog box, select “Invert side (2 engines)”.

When you choose a scheme the options for “Panel 1” and “Panel 2” are set automatically. In this case Panel 1 would not change from what you see above, but the options on Panel 2 are automatically set as follows.

I have selected Crafty as the second engine and it will analyze in single variation mode (“Chronological”). The most interesting setting in this panel is “Opponent’s moves.” With this setting selected, Crafty will analyze the moves of the side that is not to move. This is best explained with a simple example:

It is White’s move. Black has just moved his knight from f6 to d7. Analyzing this position in a normal way with infinite analysis would show you a variation that may not be of much help in understanding the position. Let’s start the analysis and see what the scheme, “Invert side (2 engines),” tells us about the position. Here we see the two analysis panels that were defined on the “Start analysis” screen. The upper panel contains analysis by Shredder 9.11 (in “Chronological” mode) and the lower panel shows Crafty’s analysis of Black’s threats. Last month we had a close look at how to read the analysis output.


Here we see the two analysis panels that were defined on the “Start analysis” screen. The upper panel contains analysis by Shredder 9.11 (in “Chronological” mode) and the lower panel shows Crafty’s analysis of Black’s threats. Last month we had a close look at how to read the analysis output.

Shredder is analyzing the position in “normal” infinite mode and it evaluates the position as much better for White (+1.90). The second panel with Crafty’s analysis gives a deeper insight into what is happening, because it is analyzing the position as if it were Black’s move. It shows us that if Black was allowed to move again, he could easily achieve a winning position (-3.62) by capturing the white knight on e5. In other words: With its last move, Nf6-d7, you could say that Black set a trap for White and threatened to win the game. Let’s take a closer look at Black’s threat. The variation given by Crafty leads to this position after 1…Nxe5 2. fxe5 Bd3:
The elimination of the knight on e5 left the d3-square wide open for the black bishop and White can’t defend the bishop on c2. It is pinned by the black rook on c8 and Black will win a piece.

This mode is especially helpful when watching games on the Internet or when studying a new opening. Next month, I plan to discuss multi-variation mode and multi-program analysis (two or more chess engines analyzing the position at the same time). I will also show how you can insert this analysis into a game.

Part Two

Last month I discussed using infinite analysis with Chess Assistant and this month I will discuss multi-variation mode and multi-program analysis (two or more chess engines analyzing the position at the same time). I will also show how you can insert this analysis into a game. Most players do not utilize the assistance of a coach and for these players in particular, a judicious use of chess engines can deepen their understanding of the game.

Multi-Program Analysis

A thorough analysis of a complicated position can be difficult, and selecting reasonable candidate moves requires imagination and understanding of the game. Many improving players will have difficulty with such analysis and that’s where a few good chess engines can come to the rescue.

Chess Assistant allows you to have several chess engines analyze a position simultaneously. Multi-program analysis is a useful feature and as computers become more powerful this type of analysis becomes more practical. Of course multi-processor/multi-core computers are ideal for multi-program analysis.
To begin, click the arrow to the right of the infinite analysis button and select “Infinite analysis…”

As you can see from the menu, the keyboard shortcut Ctrl+Space can also be used to access this function. Either way, the “Start analysis” dialog box will be displayed (see last month’s article). To access the multi-program analysis, select “Multi program (several engines)” from the “Scheme” drop-down list:
Since only “Panel 1” is used for multi-program analysis, just the relevant part of the dialog box is shown in the image. The “Type of analysis” is automatically set to “Several engines” and the usage of “Ignore moves” and “Opponent’s moves” was described last month.

What is different here is the list of installed chess engines displayed in the “Parameters” box. Shredder 9.11, Crafty, Dragon, Delfi and Ruffian all come preinstalled with Chess Assistant 10. In addition, I have installed Rybka v2.3.1, which is not included with Chess Assistant.
As shown by the checkmarks to the left of the engine list, I have selected Shredder, Crafty, Ruffian and Rybka to analyze the position. Given that these are four very different engines, they are likely to vary in their choice of moves, which is exactly what we want. When you are ready, click the OK button and the analysis will begin. Here I chose a position from Mark Dvoretsky’s February Instructor column.

The analysis pane will show the best line found by each of the four engines and after a few minutes of analysis, this is how it looked:
Shredder and Rybka prefer 18 Qc3, while Crafty recommends 18 Qe2, and Ruffian likes 18 b4. All four engines evaluate the position as favorable for White, although their evaluation varies from +0.34 (Rybka) to +0.98 (Shredder).

However, the exact evaluations are not important at this point. The key result is that by using multi-program analysis, we succeeded in finding three different moves that warrant a closer look. For the record, White actually played 18 b4!?, a move that Dvoretsky called “an outstanding counterstroke.” The other two engine moves are not analyzed by Dvoretsky, but this is a complicated position and analyzing these alternatives would be an instructive task for improving players.

The quickest way to stop the analysis is to hit the ESC button on the keyboard.

Each engine has its own strengths and weaknesses and no single engine is best for analyzing every position. Therefore, multi-program analysis can be very useful as a first step in analyzing an important position, so long as you remember that there is little benefit to letting the engines do all the analysis if you want to improve. You must first analyze the position and make your own list of candidate moves and variations. Then compare your variations with those of the chess engines and analyze the differences.

Multi-Variation Analysis
Now let’s look at multi-variation analysis. As before, we start by clicking the arrow to the right of the infinite analysis button (or Ctrl+Space) and select “Infinite analysis…” This time we select “Multivariation (1 engine)” from the “Scheme” drop-down list.

Here I have selected Rybka as the analysis engine and I set “Variations” to four in the “Parameters” pane.

The advantage of multi-variation analysis over multi-program analysis is that we are guaranteed to get four different move suggestions. Rybka will show us the move it considers best, second best and so on, up to the number specified in “Variations.” After setting the parameters, click the OK button to start the analysis. After analyzing for the same length of time as in our multi-program analysis above, Rybka displays the following results:

All the moves that were suggested in our multi-program analysis are among Rybka’s top four choices, with the addition of 18 Bd6.

As always, hitting the ESC key stops the analysis engine. If you want to save the analysis as a variation in the game, use the “Insert analysis in game” toolbar button on the “Engines” toolbar tab shown here.

The leftmost button on the “Engines” toolbar tab serves the same function as the ESC key on the keyboard. The second button (with the green arrow pointing up) saves the analysis in the game and stops the analysis.

The third button is a quick way to switch to multi-variation mode and the fourth one (“Freeze analysis”) instructs Chess Assistant to continue analyzing the current position even though you move to a different position in the game. You can even start viewing a different game from another database and the chess engine will continue its analysis of the original position.
When you save the analysis it is inserted as a variation:

The above image shows that the variation suggested by the chess engine is formatted differently from the actual game score. The engine evaluates White’s position as preferable (+0.30), it analyzed to a depth of 24 plies (d24), and it was analyzed by Rybka 2.3.1, the 64 bit version.

Advanced Example of Infinite Analysis

These two columns on infinite analysis have covered some of the most common analysis schemes, but there are many other possibilities. A good example of advanced application of infinite analysis can be found in Robert Pawlak’s article “Comparative Analysis.” It discusses a very interesting method for comparing the strength of the moves played in a game and the moves suggested by the analysis engines.


Chess Assistant offers more methods for analyzing chess games and positions than any other software. In these two columns we have limited our discussion to infinite analysis, but in the future we will discuss full game analysis and other options that are available in Chess Assistant.

Dadi Jonsson

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