Chess Assistant's use of tablebases can sometimes be confusing to new users. So in this article, I'd like to take some time to discuss how tablebases are used within the program. I will also provide some useful tips for those that are having trouble getting things set up.
Tablebases are special files that can be used to help chess engines in the endgame phase. There are three ways to get a hold of a set of Tablebases. One way is to download them - but be warned that a full five-piece set of tablebases can be a very long download indeed (measured in days or weeks, depending on connection speed). The second way is to generate them, but this requires a significant amount of processing time, depending on your computer. The third way is to simply purchase a set of CDs from one of the chess software manufacturers. Chess Assistant (and most winboard engines) employ the Nalimov format, so be sure to check if the set you are getting is the proper format.
Ok, let's assume you have the Convekta CDs, which come with their own install program. The program should prompt you for a directory to store the files in. Make sure that you pick a directory with sufficient space for all the tablebase files. The install program copies all the tablebase information to your hard drive, so it could take a while if you have a slow drive.
Usually the install goes off without incident. However if it doesn't, or if you've used tablebases from another source, then you need to configure the tablebase locations manually. So make a note of the directory that you used to store the tablebase files, because you will need it in the steps that follow.
Before I continue on with the discussion, I need to explain something about tablebase usage. In CA, there are several different locations for configuring tablebase settings. The very first place that you want to install tablebase support is in the engines setup dialog box. Click on "Engines" menu entry in the Chess Assistant window. Then select "Engines Setup" (at the bottom of the menu list).
You will then see the engines setup dialog box. On the right hand side of the dialog is a place to specify the location of the tablebase files. Click on the button with the ellipses on it. You should then see another dialog box that will allow you to specify the location, or path to the tablebase files. Navigate to the folder that you installed the tablebases to, and click the "OK" button. You should now see the path entered in the dialog box.
If you've done this correctly, it will configure tablebases for all the prepackaged Chess Assistant engines. However, if you should find that any of them are not accessing the tablebase data properly, you can set the tablebases manually for each engine.
Before doing this, it is helpful to select and copy the path that is entered into the engines setup dialog. If you don't know how to do this, then don't worry, just write it down. To configure Tiger, go back to the engines setup dialog box. Only this time, select Tiger by single clicking on it (see figure). In this example, I have clicked on Tiger 15. Then select the "Personalities" button from the bottom of the window.
You should now have both Tiger and the internal tablebase engine configured. Any engine that ships with CA will have an entry in the personalities dialog for the tablebase path. They should all be configured properly, assuming that you configure the CA tablebase engine first. If not, you can simply follow the same procedure that was outlined for Tiger. If you are trying to configure tablebase usage for a winboard engine, then you may have to edit some initialization files that are used specifically for the engine in question. Discussing this is beyond the scope of this article, since the procedure varies from engine to engine.
Incidentally, once the tablebase engine is configured in the Engines setup dialog, you will notice that you now have another chess engine available for analysis. It will appear along with the other engines listed in the dialog, at the very bottom (see figure).
If you start it in infinite analysis mode, you will notice that this engine only provides analysis when the proper number of pieces are on the board. For example, if you have installed five-man tablebase files, you will only see analysis when there are five or fewer men on the board (this includes kings). This is normal, and is the way the engine is supposed to work.
In general though, you should not need to use the CA tablebase engine, unless none of your other engines have tablebase support. This should not really happen in day to day use, since all the Tiger engines that come with CA 6.1 on, can use the tablebases.
In this article, I've discussed the installation of tablebase files within CA. Note that there are multiple places in which tablebase locations can be configured. The best configuration procedure starts with setting up the CA tablebase engine first. In normal usage, you should not need this engine, since tablebase support is built-in to Tiger. However, it pays to set it up first since it makes engine configuration faster.