1. October 28th 2001GPW20011 Using Castle and Assault Maps for Guiding Opening and Middle Game Play in Shogi Reijer Grimbergen (Saga University) Jeff Rollason (Oxford Softworks)

2. October 28th 2001GPW20012 An Opening Book for Shogi In two-player complete information games an opening book is used to guide the program in the early stage of the game The opening book of SPEAR: 1000+ professional games More than 20 books on joseki Problem: the number of expert players is relatively small, therefore The number of publicly available expert games is small The number of books on opening play is small More than 110,000 positions

3. October 28th 2001GPW20013 Using the Opening Book in Practice Opening book test: 25 games against AI Shogi 2000, Kakinoki Shogi IV, Todai Shogi 2 and Kanazawa Shogi 98:

4. October 28th 2001GPW20014 An Opening Book in Shogi: Results Our program gets out of book quickly: Within five moves in 32 games; within ten moves in 71 games Average: out of book after 8.5 moves Conclusion: an opening book is not very useful in shogi

5. October 28th 2001GPW20015 Implementation of Castle Maps Shogi has a slow build-up There are many different castles formations and ways to assault these castles Most formations take a number of moves to build Formations can have different stages Idea: use board maps of castle formations and assault formations to guide opening and middle game play

6. October 28th 2001GPW20016 Data Structure for Board Maps char **castles[] = { mino,a_mino,id_static, high_mino,a_mino,id_static, silver_crown, a_mino,id_static, boat,a_boat,id_ranging, };

7. October 28th 2001GPW20017 Piece Definition Data Structure char *mino[] = { // Non-promoted pieces// Promoted pieces mino_pawn,mino_gold, mino_lance,mino_gold, mino_knight,mino_gold, mino_silver,mino_gold, mino_gold,void,mino_bishop,mino_rook, mino_king,void, “Mino” };

8. October 28th 2001GPW20018 Square Values for Each Piece char mino_king[] = { -9,-9,-9,-9,-9,-9,-9,-9,-9, -9,-9,-9,-9,-8,-1,-1,-1,-1, -9,-9,-9,-9,-7, 0, 4, 8, 5, -9,-9,-9,-8,-6, 2, 8,14, 6, -9,-9,-9,-7,-5,-1, 8, 8, 6 } ;

9. October 28th 2001GPW20019 Strategic Guidance using Piece Maps Hill climbing approach: try to move pieces to squares with a higher value Example: if the king is on 5i in the current position, the following move sequences are suggested [K5i-K4h-K3h-K2h] or [K5i-K4h-K3i-K2h] (both paths have values [–5, 2, 8, 14]) Assault maps The assault is defined by the opponent’s castle Assault maps are defined in the same way as the castle map in the example Current implementation: 35 castle formations and 20 assault formations

10. October 28th 2001GPW200110 Using Piece Maps in a Shogi Program Select a target castle Select the corresponding assault map Use of the piece maps:  The evaluation function  To guide the search to the right move order  Guide the program to a position it can understand  Establishing the game stage  Plausible move generation

11. October 28th 2001GPW200111 Results MatchBookResult 1020304050 AllMaps vs NoMaps 38-1230-2027-2325-25 145-105 76%70%54%50% 58% CastleMaps vs NoMaps 36-1431-1925-25 23-27140-110 72%62%50% 46%56% AllMaps vs CastleMaps 27-2329-21 28-22142-108 54%58% 56%57%

12. October 28th 2001GPW200112 Related Work The otoshiana method (Yamashita 1998) also uses a hill climbing approach for building castles Only 9 different castle formations No assault formations How to assess the opponent position?

13. October 28th 2001GPW200113 Conclusions and Future Work The use of piece maps significantly improves the playing strength of a shogi program in the early stages of the game Future work Multiple castles during the search Swapping rules based on positional features Scaling of castles Assaults separate from castle formations