Aart's Blog

Rein Halbersma recently posted 8x8 checkers perft results for depth 22 with a request for confirmation (because he uses a hash table, he wanted to make sure no "hard collisions" occur). So I verified his results for depth 22 using a distributed, brute force implementation (no hash tables). The table below shows the perft breakdown per move (called "divide") from the start position for depths 20 to 22. move divide(20) divide(21) divide(22) ------------------------------------------------------- 12-16: 11531470109861 52945190026737 243598269855110 11-16: 11736729175821 53527954221225 246743868125768 11-15: 9515983205474 44775005468548 209016678583301 10-15: 10055597639275 46574865098865 215412869777867 10-14: 8600202424158 39822944739732 184865466345796 9-14: 9698986164172 45530585259776 213736468971938 9-13: 13406062152792 61923979665936 288999100078322 ------------------------------------------------------- 7454503

If your browser supports the video tag, below you will see a short movie of my first Android animation demo. Otherwise you will just see a boring text message. Let me know if this works for you; it seems an interesting new way of presenting features in my Android applications. your browser does not have   video support

I wrote my first animation on Android! It is actually part of a simple screen tester, where I can inspect the screen size of a device and see different font sizes, colors, and text positions. For fun, I added three moving balls (the circles in the screenshot below), all bouncing between the four screen borders.

I received an email from Rein Halbersma who suggested an improvement for Checkers for Android by accepting a move as soon as any ambiguity has been resolved. In many cases this enables single click input. I have implemented this request, together with extending the "move coach" to show all valid moves, as illustrated below. Hopefully this new option is useful for people that are learning checkers. Both improvements are available in v2.3 of Checkers for Android.

Although I like the wooden board textures that I use for chess and checkers, I was never quite happy with the board texture I used for Reversi for Android (some called it a dirty pool table :-). Therefore, I am trying something new in version 2.3. Instead of using a texture, I use a radial gradient on the board, which gives the impression that the board has been placed under a lamp. This new approach also slightly reduces the size of the binary. Let me know what you think.