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Classifiers are your friend!
keywords: classifiers, classes, e-books
Robert Pawlak
Saturday, July 30, 2005

Many people don't realize it, but Chess Assistant (from version 6 and above) supports a system of classifiers. Furthermore, many users are also in the dark concerning what a classifier can do. In this article, I will look at their capabilities, some of the uses for classifiers, and give a short introduction on how to use them.

What is a classifier?

A classifier is an automated way of classifying games according to certain user-specified criteria. If you can build up a search dialog for finding games according to some criteria, you can create a classifier for it as well.

Unfortunately, the term classifier is used somewhat loosely in CA instructional materials. A classifier is actually a very broad term that is used to describe a tree-like structure consisting of folders. Each folder can contain subfolders, links to trees or other folders, text articles, and multimedia elements. Each node in a folder can also contain collections of games. The nodes are defined via search criteria.

Do not confuse classifiers with classes, they are two separate entities in the CA interface, that unfortunately, share a common prefix. Classes are simply a way to mark games that might be of future interest for some reason, but are much less customizable than classifiers.

Why should you care?

Here are some of the tasks you can automate with classifiers:

Chess Assistant uses classifiers for many of its more powerful functions. For instance, Openings 2005 uses classifiers, as does the "Prepare for opponent" repertoire analysis feature.

A Practical Example of Using a Classifier

Let's say that you play the closed sicilian, and want to pull out any new games that arise from the position shown below. Normally, you would be getting your weekly database update from the Convekta server, and you would be placing these new games in something like hugebase, or some intermediate location. One way to find the games you want would be to open up the search dialog every time you wanted to search for games with that particular variation. A smarter way would be to create a classifier, which you can update with a single key stroke. While it may not seem like a large time savings for a single variation, remember that there are a number of such variations in every player's repertoire - so the savings add up quickly.

[Closed Sicilian]

To start, let's create a new classifier for hugebase. So right-click over the hugebase icon in the browser pane on the left hand side of the main window. Select "Classifier...", and create a new classifier using the "New" button and name it "Closed Sicilian". You should see a mostly empty window with something called "New Folder" on the right hand side. Right-click over the folder, and select "Edit". Then type something like "Critical Variation".

Next, right-click over the folder again, and select "Set criteria and search". This will bring up a search dialog. Click on the "Clear all criteria" button at the bottom of the window. Then click on the checkbox labeled "Position". Set up the position I have shown above, so that the search dialog looks like the picture shown below:

[Search dialog]

Then click on the "Set" button. You should then see a window with a folder followed by a number of games (279 for an unmodified version of hugebase). If you double-click on the folder now, you will be presented with a list of games that contain the position from your critical variation.

Now, if you wanted to, you could also place a picture of the board for that variation, as a memory aid. To do so, simply right-click over the folder, and select "Folder data" and then "Board". Similarly, you can set up a text note to describe the position, as I have done in the screen shot below:

[Closed Sic Final Screen]

Since classifiers have a tree-like structure, you can very easily create a large number of them to capture your entire repertoire. Then as games are added to the database, you simply select all the classifiers, and click "Update # of games" from the right-click context menu.

Classifiers can be used to automatically find anything that you can find with the search dialog. So you can imagine the possibilities for a system like this. Furthermore, they can contain complete RTF text articles, pictures, audio, and video as well. So it is possible to create entire instructional e-books with them.

Incidentally, you can download a copy of a generic classifier template that I have created for my personal use. It can help find typical sacrifices and static positional features that might arise. You can download this file from here. After downloading, create a classifier, and import the template contained in the zip file. Note that classifying hugebase with this template can take a long time, so be prepared (select all the folders, right click, and then choose update # of games).

A Few Short Words on Using Classes

As was seen in the previous example, a classifier helps to automatically search for games that might be important to you. And a classifier is really good for a well defined task like looking for games with a particular position, maneuver, player, etc. However, suppose that you find a game that you think is really important, because a particular device was used in the game. For example, let's say you are studying one of Kramnik's games, and you come across some incredibly brilliant prophylactic move that he made.

[Prophylaxis]What you would do is go to the move in question, open up the move annotation dialog (ctrl-A), and select the "Standard Classes" tab. Then click on the box labeled "Prophylaxis". Then click on "Ok". When you look at the game, you'll see a small triangle by the move, which denotes the presence of a class.

You can search for games containing a particular class marker using the search dialog. So, if you wanted to, you could use this within a classifier as well :-). At the risk of confusing matters, you might also want to note that classifiers can be used like a class. There is a function for manually assigning a specific game, or set of games to a folder. This capability is mostly intended as an aid when authoring electronic books.


Classifiers can be an incredibly powerful time saving device. In fact, the classifier mechanism underlies many of CA's advanced features, like the player encyclopedia, the Openings reference, and the opening preparation function.

Classifiers are best used for data that can be found easily via the search function, or when using the predefined classes are not sufficient.

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