We have heard from the developers of both Rybka 3 (see last month’s column) and Rybka Aquarium, the new Rybka user interface (see the April column). Now it’s time to get a sneak preview of what Aquarium is capable of. We’ll only examine one of it’s many interesting features, but it’s a feature that will be of great help for the serious chess player.

What is Interactive Deep Analysis?

Aquarium is in a class of its own when it comes to advanced analysis. It offers comprehensive game analysis and of course infinite analysis – both with features not found in other chess software – and then there is Interactive Deep Analysis (IDeA) which is the subject of this article. As Rybka Aquarium will not be released until later this summer and some of the implementation details may still change, I will concentrate only on some of the major features of IDeA instead of giving a detailed step by step description.

The purpose of IDeA is to dig deeply into a position and return as much information about it as possible. IDeA keeps its analysis in a tree structure which is unlimited in size and the user can browse at will, even while the analysis is in progress.

Besides having a live view of how the analysis is evolving the user can also direct the analysis into the most interesting positions by excluding or adding positions and variations to the analysis queue.

In short IDeA is is highly selective search controlled by Aquarium (and by the Aquarium user). Interesting lines are analyzed deeply but weak moves are only considered briefly or not at all.

There is no doubt that Interactive Deep Analysis is a very powerful tool in the hands of the serious chess player. Let’s start by seeing what IDeA looks like in action:

Interactive Deep Analysis in progress.

When IDeA is running it displays four windows:

• The familiar board window, showing the current position.
• The tree window. No, this is not the opening book window! Instead, the tree window allows you to monitor the progress of the analysis and browse the variations.
• The status window shows basic information and statistics about the analysis, such as the name of the engine, how many positions have been analyzed and how long it has been running.
• The notation window allows you to examine the position and the analysis results while it is running.

The above description of the IDeA windows only tells half the story. It is pretty accurate if you run IDeA unattended, for instance in overnight analysis, and in fact IDeA will produce very valuable analysis when running on “auto-pilot.” I expect that this simple use of IDeA will be preferred by many users, but if you are a serious chess player you may have your own views about which moves and variations are important and should be emphasized in the analysis. If you are that type of a player then you’ll appreciate the interactive part of IDeA which is described later in this article.

Stopping and Resuming an Analysis Session

IDeA stores all its analysis on disk. When the analysis starts Aquarium checks if the position has been analyzed before. If it has, then the existing analysis is loaded into the IDeA tree and instead of starting from scratch, the analysis continues where the previous analysis left off. This means that you can stop the analysis at any time, exit Aquarium and continue at a later time. The same applies even if your computer crashes (as long as the hard disk is OK) or the power goes off. The reason is that the analysis is written to disk regularly throughout the analysis process.

Note that you don’t have to restart your analysis from the same position to take advantage of this feature. As long as the position you analyze exists in the analysis tree this feature kicks in. This is a great feature for those who work on analysis over a longer period of time and gradually want to expand and deepen their analysis.

Here is an example which shows how this works. The example I used was from the famous Nolot test suite which is a collection of 11 positions. At one time it was considered unsolvable by chess engines and it is still one of the toughest test suites available. One of the hardest problems in the Nolot test suite is position number 6, which comes from the game Melaniuk-Ivanchuk, USSR 1988. It is actually the position shown in the screenshot above. Here is what I did: I started IDeA from the Nolot 6 position and then exited Aquarium after about 20 minutes, while it still considered 1…O-O to be the best move but the correct move, 1…axb5, was at that time evaluated as worse. I started Aquarium again and resumed the analysis. The image below shows how the old analysis has been loaded into the tree window after the analysis was restarted. About 9 minutes later 1…axb5 took the top spot but only after about 50 minutes it became the clear favorite with evaluation approaching equality. I should mention that for this experiment I only gave IDeA 15 seconds/position as you can see in the status window in the screenshot. This is quite a bit shorter than I would normally recommend for analysis.

Analysis can be stopped and restarted.

Control the Focus of Analysis

The tree window doesn’t only show the the moves that have been evaluated in the root position. This is an interactive tree which you can browse while analysis is running to examine all variations and positions that have been considered. Additionally you can use the tree to control which positions are analyzed. The above image shows the tree window while IDeA is running. The “Move” column shows the moves that have been evaluated. The number of positions following each move that have been analyzed is displayed in the “Positions” column. Finally the “DA” column shows the move evaluation. When you click on a move in the tree window it is highlighted like 1…axb5 in the image above. You can browse the tree using the arrow keys or the mouse.

Analyzed moves in the tree with evaluations.

If you run into a position where you want to concentrate the analysis on a particular move or moves, then you can mark them so that no other moves will be considered in that position. Here is an example. I think that 1…axb5 is the only interesting move in the current position and I don’t want IDeA to waste time analyzing other moves. To tell that to IDeA I color the move green as shown in the following image. Note that you mark the moves while IDeA is running.

Only 1…axb5 will be analyzed.

In some cases I may not be sure what the best move is, but I know that a certain move or moves are not good and I want to eliminate them from further analysis to make better use of the analysis time. What I need to do is color such moves red in the tree. The image below shows an example where I have excluded 1…O-O from further analysis. All other moves displayed in the tree will continue to be analyzed and new moves may be added to the analysis in this position.

1…O-O will not be analyzed further.

I can color as many positions in the tree as I like and thereby focus the analysis on the positions that I think are most important. Requesting Analysis of Additional Positions The move coloring method only allows you to mark moves that are already in the tree. But what if you want to request analysis of positions that are not in the there? Can you add your own moves to the tree and get them analyzed? Yes, that’s also very easy. When you browse the tree in the tree window the moves are automatically added to the notation window. If you run into a position which you find interesting you can start experimenting with it by making moves on the board. Those moves are also added to the notation window. After a while it may look like this:

Requesting analysis of additional positions.

Here I have added several variations of my own analysis. When I request analysis of a specific position it is marked with a light-blue background color. If you look at the notation window you can see that I have requested analysis of 4 different positions. Those analysis tasks will be handed over to the IDeA as high priority tasks.

	The only remaining question is how do I request analysis of a position? There are several options. You can use them both to request analysis of new positions and deeper analysis of positions that are already in the tree. The next image shows the four buttons that are used to create analysis tasks and send them to IDeA.
Different types of analysis tasks.

Current position. When you click the Current Position button, the position on the board is scheduled for analysis. It is analyzed in the same way as if IDeA had selected the position automatically.

Auto-play. The chess engine plays a number of moves starting from the current position and stores them in the tree with their evaluation. The user decides how many moves should be played.

Alternative. This option searches for a new alternative in the current position.

All positions. You are not limited to adding a single position to the analysis at a time. You can add as many moves and variations as you like to the notation window and then send them all at once to the analysis queue by clicking “All Positions”.

Adding the IDeA Results to the Notation

One advantage of IDeA is that you can leave it running as long as you wish. It just keeps expanding its analysis and adding new information to the tree until you make the decision to stop. If you leave it running overnight you can check the status in the morning and make a decision if you want to continue the analysis, perhaps after using the methods described above to make sure that the analysis will focus on the variations that are of interest to you. When you want to stop the analysis you click on the ‘Stop’ button.

	When you stop IDeA all the analysis that was added to the tree will still be available, but you are additionally given the opportunity to add the lines that were analyzed to the game notation. You are given the four options shown in the “Analysis finished” dialog box.
Do you want to add the analysis to the notation?.

You can select to keep all the analysis in the tree and not add any of it to the game notation (“Do not add lines”). Note that you can always add the lines to the notation at a later time. Simply restart IDeA from the same position and when you stop it again you can add the lines to the notation. If you select “Add best lines only” you will only see a few variations added to the notation and just the best moves that were found along with the evaluation of each variation. Transpositions are also noted. “Add all interesting lines” can add lots of variations to the notation as shown in the screenshot below. Finally, “Add current notation” copies all the moves that you entered in the notation window while IDeA was running.

All interesting lines were added to the notation.

Interactive Deep Analysis is just one example of the fresh approach that was taken in the design of Rybka Aquarium. Other interesting features of Aquarium will be described in the coming months in the next ChessOK article.

Dadi Jonsson