#Julialang based computer shogi program (@mechajyo) is introduced. Also mentions basic technics of computer shogi programs.

1. #JULIALANG AND SHOGI(JAPANESE CHESS)
twitter: @kimrin
Takeshi KIMURA

2. IN THIS PRESENTATION:
!
About us
Why we choose #Julialang
Shogi and Chess: differences between two games
principles and technics of Shogi playing software

3. ABOUT US:
Mecha Lady Shogi team (twitter = @mechajyo, 5 members):
the team of Shogi Program developers
with 2 Lady Shogi Professionals, 2 ladies and a geek:)
developing Japanese Chess Program written in #Julialang !

4. WHY WE CHOOSE #JULIALANG:
Speed
most other Shogi programs are written in C/C++
needed H/W resources: CPU and Memory access (not HDD
access)
Maintenance
dynamic language like code style is very useful for developing
Shogi programs

5. CHESS:
Chess:
8x8=64 squares
about 80 available moves in
middle game
computer programs already
won by human professionals

6. SHOGI
Shogi
9x9 = 81 squares
can reuse captured pieces
about160 available moves in
endgame
most of pieces can promote in
enemy’s field
computer programs NOT YET
win by human professionals!

7. PRINCIPLE AND TECHNICS IN
SHOGI PLAYING SOFTWARE
Alpha-Beta search
bit board and magic board technics
machine-learning evaluation functions

8. ALPHA-BETA SEARCH
problem:
in the given Shogi board representation, find best move from
its available moves
solution:
search partial tree of game tree and find a best move and root
node’s tree value(Evaluation Value)
Depth-first search by using a recursive function

9. function AlphaBeta( gs::GameStatus, WB, depth, alpha, beta)
if depth <= 0.0
va = eval(gs, alpha, beta)
return va
end
moves = generate(gs)
for i = 1:length(moves)
makeMove( gs, moves[i], WB)
val = -AlphaBeta( gs, WB$1, depth-1.0, -beta, -alpha)
takeBack( gs, moves[i], WB)
if val > alpha # alpha-update
alpha = val
# save this move
if alpha >= beta # beta-cutoff
return beta
end
end
end
alpha
end
return eval
(leaf node)
generate moves
(good move first)
pseudo code
(simplified)
recursive
calls
find good moves
cutoff redundant
search

10. PSEUDO CODE SUMMARY
If node is leaf node, return the value of evaluation function
Generate child node moves(=available moves)
For each moves:
Make move
Call myself(=this function) in NegaMax manner
Take back move
If it’s good move, record this move(=Alpha Update)
if very good move, cutoff subsequent child node’s search(Beta Cutoff)
return beta
return alpha

11. BITBOARD TECHNICS
(IN MOVE GENERATION)
In chess programs, board representation is 64bit Unsigned Integer
value: each bit represents existence of pieces
Pawn, Knight,…, King, for each piece kinds, there are 2 bitmap
values(one for White, another for Black)
In Shogi programs, square of the board is 81. So in ordinal
programming languages(such as C++), we use 3x32bit Unsigned
Integer = 96bit bitmap values
#Julialang’s 128bit Unsigned Integer is suitable for storing 81bit Shogi
bitmaps!

12. BASIC IDEAS OF BITBOARD
for each pieces of white side(for example: White King):
get piece position that of move from
dest = BitMapTable( piece, from, White) # available moves table
dest &= (not White pieces) # with single bitwise AND!
for each dest bits:
generates Move and stores move buffers

13. SOURCE CODE OF WHITE KING
target = (~p.WhitePieces) & MaskOfBoard
!
bbp = p.bb[MJOU] #White King’s bitmap
while bbp > uint128(0)
from = trailing_zeros(bbp)
bbp $= BitSet[from+1]
dest::BitBoard = target & gs.AttackTableNonSlide[MJOU,from+1]
toru::BitBoard = dest & p.BlackPieces #captured pieces
while dest > uint128(0)
to = trailing_zeros(dest)
dest $= BitSet[to+1]
toriflag = ((toru & BitSet[to+1]) > 0)?FLAG_TORI:0
count += 1
out[count] = Move(MJOU,from,to,toriflag,p.square[to+1]&0x0f,0)::Move
InsertMoveAB(count,out,gs)
end
end

14. MJOU = White King(OU,王)
tori/toru = capture
!
Magic board (More advanced technics):
calculate dest bitmap by multiples MAGIC numbers(one
direction hash)

15. MACHINE LEARNING
EVALUATION FUNCTIONS
This technic is established by Hoki-san’s “Bonanza” program
Evaluation function value = dot(WeightVector, FeatureVector)
Val = w1*f1 + w2*f2 + … + wn*fn
Hoki-san established the way of learning Weight Vectors by Machine Learning(reinforcement
learning)
King - OpponentKing - another piece relationships
King - piece - and another piece relationships
(Three pieces relationships)
We use Hoki-san’s fv.bin for calculation function values

16. CONCLUSION:
We will attend WCSC24 (The 24th World Computer Shogi Championship)
Mecha Lady Shogi (メカ女子将棋, @mechajyo) is using #Julialang
for her programming language
メカ＝Mecha, 女子＝Girl, Lady
But actually, playing ability of mechajyo is not so strong :(
We will also attend DenOu Sen tournament (電王戦トーナメント) may will be hold in Nov. 2014
電王＝Electrical King
Thank you!