Java checkers' first draw against Cake

My Java checkers engine now has its own - very primitive - GUI based on Swing, and I can let it play games against my other engines. Here is its first game against Cake:

[Event "test game"]
[Date "2009-03-18"]
[Black "Cake 1.8"]
[White "Java engine"]
[Result "1/2-1/2"]
1. 11-15 22-18 2. 15x22 25x18 3. 8-11 29-25 4. 4-8 25-22 5. 12-16 24-19 6. 16-20 19-15 7. 10x19 23x16 8. 6-10 16-12 9. 9-14 18x9 10. 5x14 26-23 11. 2-6 22-18 12. 14-17 21x14 13. 10x17 31-26 14. 6-10 23-19 15. 1-6 19-15 16. 10x19 26-22 17. 17x26 30x16 18. 6-10 28-24 19. 10-15 18-14 20. 15-18 14-10 21. 7x14 16x7 22. 3x10 12x3 23. 18-22 3-7 24. 22-26 7-2 25. 10-15 2-7 26. 15-18 7-10 27. 14-17 10-14 28. 18-22 14x21 29. 26-31 21-17 30. 22-25 17-22 31. 25-30 32-28 32. 30-26 22-25 33. 26-30 25-22 34. 30-26 22-18 35. 26-30 1/2-1/2

This one draw doesn't mean too much of course - in its next game, it got into trouble against simple checkers, but just managed to escape with a draw. There is still a lot of knowledge missing in the evaluation function... And the GUI will need a lot more attention too!

Java perft, again

After some more optimizations my Java perft now runs much faster than before, it is now nearly half as fast as the C code. I would have expected much less from Java and am pleasantly surprised. I'm quite happy already with the Java engine, so now for the hard part - creating an interface....

perft 1 time 1 positions 7 kN/s 7
perft 2 time 1 positions 49 kN/s 49
perft 3 time 1 positions 302 kN/s 302
perft 4 time 1 positions 1469 kN/s 1469
perft 5 time 1 positions 7361 kN/s 7361
perft 6 time 15 positions 36768 kN/s 2451
perft 7 time 1 positions 179740 kN/s 179740
perft 8 time 63 positions 845931 kN/s 13427
perft 9 time 250 positions 3963680 kN/s 15854
perft 10 time 1156 positions 18391564 kN/s 15909
perft 11 time 5437 positions 85242128 kN/s 15678
perft 12 time 24954 positions 388623673 kN/s 15573

Java checkers' first sensible game

After improving the evaluation function a bit and after adding some standard search improvements, my Java checkers engine now appears to be playing a good game. It searches 3 million positions per second on my 2GHz Core Duo laptop, and typically gets around 17 ply search depth within a few seconds (that is faster than simple checkers, and a few ply deeper than simple checkers). It can't use endgame databases (yet?!) and has no opening book, but apart from that it is "Cake light" - a simplified version of Cake, using parts of the evaluation and parts of the search strategies that Cake does - but all on a much less complex level. The code is a joy to read compared to the Cake source code :-) (and much shorter). I will still have to improve the "Javaness" of the code - coming from a procedural language, I am writing C-style code in Java...

Here is the first sensible game of the engine playing against itself - red got a winning position but then blew it. But at least this already looks like checkers to me.


[Event "test game"]
[Date "2009-03-08"]
[Black "Java Engine"]
[White "Java Engine"]
[Result "1/2-1/2"]
1. 11-15 22-18 2. 15x22 25x18 3. 8-11 29-25 4. 4-8 25-22 5. 11-16 23-19 6. 16x23 26x19 7. 9-14 18x9 8. 5x14 27-23 9. 8-11 22-18 10. 14-17 21x14 11. 10x17 24-20 12. 17-22 32-27 13. 1-5 30-26 14. 6-10 26x17 15. 10-15 19x10 16. 7x21 23-19 17. 2-7 27-24 18. 21-25 19-16 19. 12x19 24x8 20. 3x12 18-14 21. 25-30 28-24 22. 30-25 31-26 23. 25-21 26-22 24. 21-25 22-18 25. 25-22 18-15 26. 22-26 15-10 27. 5-9 10x3 28. 9x18 24-19 29. 18-22 3-7

Java checkers' first game

My as yet unnamed Java checkers engine just played its first game against itself! Apparently, there is still some room for improvement...

[Event "Test"]
[Date "3rd March 2009"]
[Black "Java Engine"]
[White "Java Engine"]
[Result "1/2-1/2"]
1. 11-15 22-18 2. 15x22 25x18 3. 8-11 29-25 4. 12-16 25-22 5. 16-20 24-19 6. 9-13 19-16 7. 5-9 28-24 8. 10-15 16-12 9. 6-10 23-19 10. 11-16 18x11 11. 16x23 27x18 12. 20x27 32x23 13. 7x16 22-17 14. 13x22 26x17 15. 9-13 30-26 16. 13x22 26x17 17. 16-20 31-27 18. 4-8 23-19 19. 8-11 17-13 20. 11-16 27-23 21. 20-24 18-14 22. 10x17 21x14 23. 24-27 19-15 24. 27-31 15-11 25. 31-26 23-18 26. 16-20 11-8 27. 26-22 18-15 28. 22-17 15-10 29. 20-24 8-4 30. 2-6 10-7 31. 17x10 7-2 32. 24-28 2x9 33. 1-5 4-8 34. 5x14 13-9 35. 28-32 9-5 36. 10-15 5-1 37. 14-18 8-4 38. 18-23 1-6 39. 23-27 6-2 40. 27-31 2-6 41. 15-11 6-2 42. 31-26 2-6 43. 32-28 6-2 44. 26-23 2-6 45. 23-26 6-2 46. 26-23 2-6 47. 23-26 6-2 48. 26-23 2-6 49. 23-26 6-2 50. 26-23 2-6

and a draw by repetition because it doesn't yet understand the concept of progress...

Java perft

I just finished debugging a Java checkers move generator - thanks to perft I found some bugs, and just watched the first game of my Java checkers engine played against itself (not a nice sight). Not surprisingly (at least to me), the Java code runs much slower than the C code - I found a factor 3.2 difference. Is that just me, or is it Java??

C (Cake's code without move ordering)
depth 1 positions 7 time 0.000000 1.$ kN/s
depth 2 positions 49 time 0.000000 1.$ kN/s
depth 3 positions 302 time 0.000000 1.$ kN/s
depth 4 positions 1469 time 0.015000 97.9 kN/s
depth 5 positions 7361 time 0.000000 1.$ kN/s
depth 6 positions 36768 time 0.000000 1.$ kN/s
depth 7 positions 179740 time 0.000000 1.$ kN/s
depth 8 positions 845931 time 0.063000 13427.5 kN/s
depth 9 positions 3963680 time 0.156000 25408.2 kN/s
depth 10 positions 18391564 time 0.547000 33622.6 kN/s
depth 11 positions 85242128 time 2.656000 32094.2 kN/s
depth 12 positions 388623673 time 12.266000 31683.0 kN/s

Java
perft 1:7 1ms 7000positions/sec
perft 2:49 1ms 49000positions/sec
perft 3:302 1ms 302000positions/sec
perft 4:1469 17ms 86000positions/sec
perft 5:7361 1ms 7361000positions/sec
perft 6:36768 16ms 2298000positions/sec
perft 7:179740 17ms 10572000positions/sec
perft 8:845931 79ms 10707000positions/sec
perft 9:3963680 392ms 10111000positions/sec
perft 10:18391564 1813ms 10144000positions/sec
perft 11:85242128 8486ms 10045000positions/sec
perft 12:388623673 39141ms 9928000positions/sec

A postscript a couple of days later: I managed to improve my Java code a bit, it is now only 2.3 times slower than the C code. I suppose that is about the best one can hope for with Java - or??

perft for checkers

A couple of days ago I got a mail from Aart Bik, a programmer working at Google. He is currently developing a checkers application (among others) for the Google android platform (aka gPhone). He asked me about perft numbers for checkers. Perft is an invention of the chess programming community, a test to verify the correctness of the move generator, by printing how many legal moves exist in a search tree to depth N from the current position. Although I have this function in my chess engine, I never thought of adding it to Cake until now. However, Aart is right, and a perft function is always good to have for debugging purposes, so I added it to Cake. In the next CheckerBoard/Cake release, Cake will have this functionality. For starters, here are the numbers Cake reports from the initial position:

depth 1 positions 7
depth 2 positions 49
depth 3 positions 302
depth 4 positions 1469
depth 5 positions 7361
depth 6 positions 36768
depth 7 positions 179740
depth 8 positions 845931
depth 9 positions 3963680
depth 10 positions 18391564
depth 11 positions 85242128
depth 12 positions 388623673

Aart is happy too, since his numbers match. If you are interested in his applications for the gPhone, then check out his blog.

Dweeb!

I just heard that Jonathan Schaeffer published a revised version of his book on Chinook, One Jump Ahead. I own it, and it was one of the things that motivated me to work on checkers. In the new version, some new material was added on the solution of checkers by the Chinook team, which probably also makes good reading. I also get mentioned in the book - although I'm rather on the receiving end:


"Darse Billings and many other people were upset at the junk that was being posted on the web. Darse sent out the following message:

Who the hell is this dweeb? I read the report of the Las Vegas tournament and was appalled with his obnoxious and slanderous comments against Jonathan. Someone should teach him some manners.
Personally, I see no reason for Jonathan to accept a challenge from NEMESIS - CHINOOK doesn't have to prove anything to anywone. The program did enough talking eight years ago - long before the pipsqueaks started squeaking. But if he does grant them a match, I hope it will only be after sufficient preparation to blow them out of the water. Punks."


Darse (and Schaeffer with his Junk) is referring to my report on the Las Vegas world championship (As a side note, Darse was not on the Chinook team, and not a checkers programmer - exactly what his qualifications would be to judge the claims in my report remains a mystery to me).


Well, at least I learned some new English curse-words :-)

4 in a row source code

I just published the source code of my 4 in a row program on my four in a row page. While this doesn't appear to fit in a computer checkers blog, I think it does belong for two reasons: first, it is an example of how to write a high-performance game program. Second, this is the second part of my plan to publish some of my source code (CheckerBoard came in first). More to follow...

CheckerBoard source code release

My interest in computer checkers is waning - partly because the game is solved, partly because other interests are taking more of my time these days. I still sometimes get mail asking for new features in CheckerBoard, but I haven't done much lately. Since I don't think this will change anytime soon, I have made the source code of CheckerBoard (in version 1.651) public. This code can be used in any way you might see fit; I'm not going to bother with some kind of public license.
I am very much aware that the code is neither particularly good nor clean; CheckerBoard was - like perhaps most software - not really designed well, i.e. it started out as a simple program and then I kept on adding more and more things to it, and so the whole program structure isn't nice. Some of the source code is really old, written at a time when my programming skills were even less developed than they are now. And of course, I'm not a trained programmer who learned how to properly develop software. All of this will make the CheckerBoard source code rather hard to understand, but if you have a lot of patience and a decent working knowledge of standard C, then you can probably get to grips with it.

CheckerBoard 1.651

I just published CheckerBoard 1.651 on my webpage. This release fixes four things:

1) a serious synchronization bug between the multiple threads of CheckerBoard, which could show up in autoplay and engine match mode; on my two newer machines that I usually use for development, this bug didn't show, but on my oldest machine it was very obvious. Even if the bug didn't show clearly on the newer machines, it is possible that it affects engine match outcomes - an upgrade is therefore strongly recommended if you run engine matches.

2) a small bug with graphics updating when changing the piece set (the board would update, the pieces only on the next window resizing).

3) export to HTML now also works from setup positions for Italian checkers (it always worked for English checkers)

4) I forgot to include the file 11man_FEN.txt which is used for 11-man engine matches. It contains 2400 of the 2500 possible 11-man starting positions. 100 of the positions are omitted, because they are likely wins for one side. The newest release includes this file, so that 11-man engine matches with 4800 games can be run (if you have the patience...) for better statistics than with standard engine matches.

If I get no negative feedback on this release, I will also publish the source code of CheckerBoard, since I find it increasingly difficult to find the time to work on CB - making the source public is a better alternative to stopping the development altogether.

But now, enjoy your bug-free 11-man matches!