Keywords: Software, Online Go

Viking and Valkyria are computer go programs that are written by Magnus Persson (Zapp on KGS). This page is about older versions of my programs.

Viking 4

This older version of Viking uses a very complex full board evaluation function to find good moves. The evaluation function and move generation rely heavily on 1000's of handmade patterns.

14 Mar 04: Was able to connect to KGS with kgsGTP.

Viking 5

Since it was very hard to improve Viking4 I decided to try the monte carlo approach that seems very popular among new bot writers on KGS. Thus Viking5 is a new program but uses a lot of code from Viking 4. I added some extra knowledge about eyes and simple ladders to improve the basic MC algorithm and it started to play quite well. It also uses alfa beta full board search which gets to 2-3 ply on 9x9 in the 30 seconds it uses per move.

It has a fuseki library for 9x9 and 7x7. I add test games and games from KGS to the library. If you beat it, it will learn which moves are good and bad. There are more than 15000 games in the library but most of them are from test games against other bots and has a strong tendency to repeat the same moves over and over again.

The 7x7 fuseki library consists on more than 200 games, with human players only. It is interesting because it is probably possible to develop a strong fuseki library with just a few 100 games. If you play white with the default 7.5 komi it is difficult to win. Note that the correct komi is probably 9.5 for 7x7. This mean that playing black against Viking with the standard 7.5 komi gives you an advantage. If you play white with correct or reduced komi on the other hand I think it is much more of challenge.

Previously Viking5 was very weak with big boards. In january I added a pattern database for move ordering and a system to avoid moves inside territory. This means it plays much stronger on big boards How much is still unknown. It might also be slightly stronger on 9x9 but I do not think it is much of a difference.

3 Feb 05: Viking5 is tested on KGS for the first time.
2 June 05: Fuseki library for 9x9 added!
10 July 05: Second place in the Open 9x9 CG KGS Tournament. [ext]
12 July 05: Fuseki library for 7x7 added!
5 August 05: Updated fuseki libraries with new games. IMPORTANT! Some minor tactical improvements. Currently I cannot use KGS games with undo in them so if you want your games to improve viking you should not use undo.
8 August 05: I decided to simplify the code and remove some old stuff. In that process I must have deleted some severe bugs, because the playing strength against Gnugo increased more than anything I did for a long time. Hint to all programmers: best way of improving the program is to delete old code ...
4 September 05: Split first place in the Formal Division 9x9 CG KGS Tournament. [ext] In this tournament I was able to use a 3 Ghz P4 rather than my laptop. The long time controls also favored viking5.
6 November 05: Split fourth place in the 8th Formal Division CG KGS Tournament. [ext] The fuseki library was of no use against the stronger programs. I was running on my 1.7GHz laptop so Viking was weaker and the competition was tougher than ever.
6 December 05: Updated fuseki database with KGS games from November. Thanks to all who played on 7x7!
4 January 06: Viking5 now has proper pattern based move ordering. This improves playing strength on 13x13 and 19x19 a lot.
8 January 06: Fourth place in the 10th Formal Division CG KGS Tournament. [ext] The new version played very strong but it lost a game because of an obscure bug when it resigned instead of passing. The bug was easy to fix.
5 Febuary 06: Second place in the 11th Formal Division CG KGS Tournament. [ext] The first tournament on 13x13. I am happy with how Viking played.
19 Febuary 06: I disabled undo for Viking, because a) The 9x9 rating suffers from people abusing undo b) I cannot use game records where undo was used for the fuseki library.
6 March 06: Viking5 now also plays on the ComputerGoServer for 9x9 go. It is currently on the top of the rating list. It is my laptop which plays these games which means it plays stronger than the computer I use for KGS games.
23 March 06: I created a new fuseki library for 9x9 since the old one contained too many games with bad moves.
6 August 06: First place playing 13x13 in the 17th Formal Division CG KGS Tournament. [ext] I sacrificed evaluation accuracy for deeper search, and a little luck helped as well
16 August 06: Fixed a bug for KGS where Viking would never stop thinking in extreme blitz games with Byoyomi.

Viking last edited by on August 17, 2008 - 16:46
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