Kingsrow Italian

Kingsrow Italian is a program that plays Italian checkers. It is used with Martin Fierz's user interface program called CheckerBoard. Both Kingsrow and CheckerBoard are free programs and can be downloaded using the links below. 


The CheckerBoard install files below are more current than the ones at Martin's site. They have new bug fixes, enhancements for PDN3.0, and the PDN search function now works with all the different checkers variations supported by the program, including Italian.

Opening Book 

Kingsrow Italian has an opening book database of 1.04M positions. It covers all 174 of the 3-move openings, including 8 which this book shows are probably losses. The book was built by doing systematic searches with Kingsrow and the 10-piece database. This technique is called dropout expansion and was developed by Thomas Linke. It is described in his paper "Exploring the Computational Limits of Large Exhaustive Search Problems". Martin Fierz has written an overview of how dropout expansion works.

Here is a summary table with some statistics on the opening book.

Endgame Databases

New as of June 2016, the complete 10-piece database for Kingsrow Italian is available for download. For the past 10 years only a small subset of 5x5 positions (with no more than 1 king on a side) had been available. The new database is in a different format than the previous one. It uses better compression techniques that result in smaller files. For example, the files for 2 through 9 pieces used to be 45gb; in the new format they are 18gb. The total size for 2 through 10 pieces is 117gb.

The WLD data gives Kingsrow a huge increase in playing strength. During a search, many lines will trade down to positions that are in the db, even when the game position has 18 or 20 pieces. By propagating these db values back to the game position, the program is able to see the end result from positions very early in the game.

Also available for download is a moves-to-conversion (MTC) database. This db helps the program play some winning endgame positions that require very many moves for the win to be consummated (or to defend those positions if it is playing the losing side). It is consulted before each search, but is not used during a search, so it uses very little cache RAM and does not affect the search speed. Some related information about the 10-piece MTC database that I built for English checkers is here. Use of the MTC database is optional. The program will correctly play most endings without it. But if you are interested in seeing the correct play to some difficult endings then you may find that this addition is useful. For example, it shows how to play this ending, which is a black win, but if white defends perfectly it requires 147 king moves before black can force a man or capture move (thus making visible progress towards the conclusion of the game).

 [FEN "B:WK9,K14,K29:BK6,K24,K26,25."] 

The following Italian 8-piece position has the longest moves to conversion that I have found in either Italian or English checkers, including 9-piece and 10-piece English positions. This remarkable position requires 219 king moves before black can force a conversion move. 

[FEN "B:WK7,K9,K24,23:BK2,K1,K8,K15."]

Download a complete list of the longest MTC positions in each database subdivision. You can copy the FEN positions to the Windows clipboard and paste them directly into CheckerBoard. Click here to download.

Obtaining Endgame Databases

You can download install files for the endgame databases using the links below. To use the 9 and 10-piece databases, you also need to install the databases of 2 through 8 pieces. The files are hosted at Mega. For downloading these large files, Mega only supports Chrome and Opera web browsers. More about downloading from Mega.

Each install contains a group of .bin files and an .exe setup program file. Download all the files to your PC, then run the setup program to install the database on your hard drive.

If you have the earlier version of the endgame databases, either delete those files first, or install these files in a different directory. Kingsrow will work with either version of the databases, but the older version files take up a lot of space on your hard drive, and there is no reason to keep them if you have the new databases. After you install the new databases, you should tell kingsrow where you put them. Use the Checkerboard menu Engine, Options, More Options, and use the Browse... button under WLD database to enter the directory path to the db files.

Ed Gilbert
Last revised: October 12, 2018.