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Searching over Metapositions in Kriegspiel Andrea Bolognesi and - - PowerPoint PPT Presentation

Searching over Metapositions in Kriegspiel Andrea Bolognesi and Paolo Ciancarini {abologne,ciancarini}@cs.unibo.it Dipartimento di Scienze dellInformazione University of Bologna - Italy Searching over Metapositions in Kriegspiel p.1/34


slide-1
SLIDE 1

Searching over Metapositions in Kriegspiel

Andrea Bolognesi and Paolo Ciancarini

{abologne,ciancarini}@cs.unibo.it

Dipartimento di Scienze dell’Informazione University of Bologna - Italy

Searching over Metapositions in Kriegspiel – p.1/34

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SLIDE 2

Index

Perfect vs imperfect information Exploiting the referee’s answers The game of Kriegspiel The search algorithm Research Highlights Searching through metapositions Example of Kriegspiel game The evaluation function Example of position The rook ending (

) Using metapositions The queen ending (

) Metapositions The ending with two Bishops Cardinality of pseudomoves The pawn ending (

) The game tree Conclusion

Searching over Metapositions in Kriegspiel – p.2/34

slide-3
SLIDE 3

Perfect vs imperfect information

  • Games of perfect information:
  • the current state of the game is fully accessible to

each player;

  • the uncertainty is all about future moves;
  • Chess, Checkers.
  • Games of imperfect information:
  • players have partial knowledge about the current

state of the game;

  • a player may not know what any other player has

done up to that moment;

  • Poker, Kriegspiel.

Searching over Metapositions in Kriegspiel – p.3/34

slide-4
SLIDE 4

The game of Kriegspiel

I II R

✆ ✆ ✆ ✝ ✞ ✆ ✆ ✆ ✟ ✠ ✆ ✆ ✆ ✝ ✡ ✆ ✆ ✆ ✟ ☛ ✆ ✆ ✆ ✝ ☞ ✆ ✆ ✆ ✟ ✌ ✆ ✆ ✆ ✝ ✍ ✆ ✆ ✆ ✟ ✎ ✏ ✑ ✆ ✆ ✝ ✞ ✒ ✓ ✆ ✆ ✟ ✠ ✔ ✑ ✆ ✆ ✝ ✡ ✕ ✓ ✆ ✆ ✟ ☛ ✖ ✑ ✆ ✆ ✝ ☞ ✗ ✓ ✆ ✆ ✟ ✌ ✘ ✑ ✆ ✆ ✝ ✍ ✙ ✓ ✆ ✆ ✟ ✎ ✏ ✑ ✆ ✆ ✆ ✒ ✓ ✆ ✆ ✆ ✔ ✑ ✆ ✆ ✆ ✕ ✓ ✆ ✆ ✆ ✖ ✑ ✆ ✆ ✆ ✗ ✓ ✆ ✆ ✆ ✘ ✑ ✆ ✆ ✆ ✙ ✓ ✆ ✆ ✆
  • Kriegspiel is a game for two players, but it needs a

referee;

  • Neither player knows any position of his opponent’s

pieces,

  • Each player has to guess his opponent’s state of play by

choosing moves to which the referee can reply by

  • being silent;
  • saying“illegal”;
  • saying“check”

.

  • saying“captured {piece,pawn} on square xy”.

Searching over Metapositions in Kriegspiel – p.4/34

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SLIDE 5

Research Highlights

  • M. Leoncini and R. Magari. Manuale di Scacchi Eterodossi.

Tipografia Senese, Siena,1980.

  • J. Boyce. A Kriegspiel Endgame. In D. Klarner ed., The

Mathematical Gardener, pag 28-36. Prindle, Weber & Smith, 1981.

  • T. Ferguson. Mate with Bishop and Knight in Kriegspiel.

Theoretical Computer Science, 96:389-403, 1992.

  • T. Ferguson. Mate with two Bishops in Kriegspiel. Technical report,

UCLA, 1995.

  • P. Ciancarini, F. Dalla Libera and F. Maran. Decision Making under

Uncertainty: A Rational Approach to Kriegspiel. In J. van den Herik and J. Uiterwijk editors, Advances in Computer Chess 8, 1997.

  • M. Sakuta and H. Iida. Solving Kriegspiel-like Problems: Exploiting

a Transposition Table. ICCA Journal, 23(4):218-229, 2000.

  • L. Shapley and A. Matros. The invisible Chessboard or Meeting with

Lloyd Shapley. 64-Chess Review, #10, pages 58-59, 1999.

Searching over Metapositions in Kriegspiel – p.5/34

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SLIDE 6

Why Kriegspiel is interesting

  • Same rules as chess (well, most of them are similar), so we can hope

to exploit current computer chess knowledge and technology

  • Chess is 99 % Tactics, Krigspiel is more strategy oriented
  • No opening theory is possible (however strategies can be classified)
  • Some Endings can be analyzed algorithmically
  • Some Endings need game theoretic analysis
  • A corpus of thousands of problems exist
  • Well known game on ICC, played by hundreds of players (even blitz)
  • No strong programs do exist: all of them have the problem of

progressing to victory knowing nothing about the opponent’s position

Searching over Metapositions in Kriegspiel – p.6/34

slide-7
SLIDE 7

Example of Kriegspiel game

The following animation shows an example of Kriegspiel game played by Paolo Ciancarini agains Krieg on ICC in April 2003. Click here to skip the animation.

SKIP

Searching over Metapositions in Kriegspiel – p.7/34

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SLIDE 8

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✤ ✥ ✦ ✧ ★ ✩ ☎ ☎ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✣ ✥ ✦ ✧ ★ ✩ ☎ ☎ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✤ ✥ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-9
SLIDE 9

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✤ ✥ ✦ ✧ ☎ ★ ✩ ☎ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

1.e4

✚ ✣ ✥ ✦ ✧ ☎ ★ ✩ ☎ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✤ ✥ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-10
SLIDE 10

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✤ ✥ ✤ ✦ ✧ ☎ ★ ✩ ☎ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 1. ..e6
✚ ✣ ✥ ✦ ✧ ☎ ★ ✩ ☎ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✤ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-11
SLIDE 11

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✤ ✥ ✤ ✦ ✧ ☎ ★ ✩ ☎ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

2.d4

✚ ✣ ✥ ✦ ✧ ☎ ★ ✩ ☎ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✤ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-12
SLIDE 12

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✥ ✤ ✦ ✧ ☎ ★ ✩ ☎ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 2. ..f6
✚ ✣ ✥ ✦ ✧ ☎ ★ ✩ ☎ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-13
SLIDE 13

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✩ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

3.c4

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✤ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-14
SLIDE 14

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✩ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 3. ..d6
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-15
SLIDE 15

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✩ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

4.f4

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✂ ✢ ✣ ✤ ✤ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-16
SLIDE 16

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✩ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 4. ..Kf7
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ☎ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-17
SLIDE 17

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

5.g4

✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-18
SLIDE 18

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 5. ..g6
✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-19
SLIDE 19

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

6.h4

✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-20
SLIDE 20

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 6. ..Qe7
✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-21
SLIDE 21

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

7.b4

✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✢ ✣ ✤ ✂ ✤ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-22
SLIDE 22

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✤ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • ne pawn try
  • 7. ..h5
✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ☎ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✤ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-23
SLIDE 23

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✤ ✧ ☎ ☎ ☎ ☎ ★ ✩ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

8.a4

✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ☎ ★ ✩ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✤ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-24
SLIDE 24

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ✤ ★ ✩ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

pawn capture in g4

  • 8. ..h×g4
✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✪ ✫ ✄ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ✤ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-25
SLIDE 25

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✜ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ✄ ★ ✩ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

9.Q×g4

pawn capture in g4

✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ✄ ★ ✩ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✜ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-26
SLIDE 26

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ✄ ★ ✩ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 9. ..Bd7
✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ✄ ★ ✩ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-27
SLIDE 27

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

10.Qe2

✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-28
SLIDE 28

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 10. ..a5
✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-29
SLIDE 29

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

11.b×a5

pawn capture in a5

✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-30
SLIDE 30

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

pawn capture in a5

  • 11. ..R×a5
✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-31
SLIDE 31

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

12.Bd2

✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-32
SLIDE 32

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✜ ✂ ✥ ✛ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 12. ..Ra6
✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✫ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✜ ✂ ✥ ✛ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-33
SLIDE 33

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✜ ✂ ✥ ✛ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

13.Nc3

✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✜ ✂ ✥ ✛ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-34
SLIDE 34

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✜ ✂ ✥ ✛ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 13. ..Qe8
✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✜ ✂ ✥ ✛ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-35
SLIDE 35

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✜ ✂ ✥ ✛ ✤ ✤ ✦ ✧ ☎ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

14.Nf3

✚ ✣ ✥ ✦ ✧ ☎ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✜ ✂ ✥ ✛ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-36
SLIDE 36

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ✛ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

pawn capture in a5

  • 14. ..R×a4
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ✛ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-37
SLIDE 37

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ✫ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

15.N×a4

piece capture in a4

✚ ✣ ✥ ✦ ✧ ✫ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✜ ✂ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-38
SLIDE 38

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ✜ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

piece capture in a4

  • 15. ..B×a4
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ✜ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-39
SLIDE 39

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ✁ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

16.R×a4

piece capture in a4

✚ ✣ ✥ ✦ ✧ ✁ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-40
SLIDE 40

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ✵ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

piece capture in a4

  • 16. ..Q×a4
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ✵ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-41
SLIDE 41

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ✵ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

17.Ba5

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ✵ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-42
SLIDE 42

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 17. ..Qe8
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-43
SLIDE 43

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

18.Bc3

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-44
SLIDE 44

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • ne pawn try
  • 18. ..e5
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-45
SLIDE 45

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

19.d×e5

pawn capture in e5

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-46
SLIDE 46

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

pawn capture in e5

  • 19. ..d×e5
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-47
SLIDE 47

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

20.f×e5

pawn capture in e5

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-48
SLIDE 48

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

pawn capture in e5

  • 20. ..f×e5
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✫ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-49
SLIDE 49

PaoloC-Krieg, ICC Aprile 2003

✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

21.N×e5

check by knight; pawn capture in e5

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✵ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-50
SLIDE 50

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

piece capture in e5

  • 21. ..Q×e5
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-51
SLIDE 51

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

22.B×e5

piece capture in e5

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✂ ✥ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-52
SLIDE 52

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 22. ..Na6
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-53
SLIDE 53

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

23.Bc3

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-54
SLIDE 54

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 23. ..Bb4
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-55
SLIDE 55

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

24.Kd2

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-56
SLIDE 56

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 24. ..Bf8
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✩ ✄ ✪ ✬ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-57
SLIDE 57

PaoloC-Krieg, ICC Aprile 2003

✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ☎ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

25.Bh3

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✢ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-58
SLIDE 58

PaoloC-Krieg, ICC Aprile 2003

✚ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ☎ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 25. ..Ne7
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-59
SLIDE 59

PaoloC-Krieg, ICC Aprile 2003

✚ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ☎ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

26.Rf1

check on file

✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-60
SLIDE 60

PaoloC-Krieg, ICC Aprile 2003

✚ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✢ ✧ ☎ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • ne pawn try
  • 26. ..Nf5
✚ ✣ ✥ ✦ ✧ ☎ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✢ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-61
SLIDE 61

PaoloC-Krieg, ICC Aprile 2003

✚ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ☎ ✧ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

27.e×f5

piece capture in f5

✚ ✣ ✥ ✦ ☎ ✧ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✣ ✤ ✂ ✥ ✢ ✤ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-62
SLIDE 62

PaoloC-Krieg, ICC Aprile 2003

✚ ✣ ✤ ✂ ✥ ✢ ✦ ✤ ✧ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

pawn capture in f5

  • 27. ..g×f5
✚ ✣ ✥ ✦ ✧ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✣ ✤ ✂ ✥ ✢ ✦ ✤ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-63
SLIDE 63

PaoloC-Krieg, ICC Aprile 2003

✚ ✣ ✤ ✂ ✥ ✢ ✦ ✬ ✧ ☎ ★ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

28.B×f5

pawn capture in f5

✚ ✣ ✥ ✦ ✬ ✧ ☎ ★ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✣ ✤ ✂ ✥ ✢ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-64
SLIDE 64

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✣ ✤ ✂ ✥ ✢ ✦ ✬ ✧ ☎ ★ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • 28. ..Rg8
✚ ✣ ✥ ✦ ✬ ✧ ☎ ★ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✣ ✤ ✂ ✥ ✢ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-65
SLIDE 65

PaoloC-Krieg, ICC Aprile 2003

✚ ✛ ✣ ✤ ✂ ✥ ✢ ✦ ✧ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

29.Bd3 # 1-0

checkmate

✚ ✛ ✣ ✤ ✂ ✥ ✢ ✦ ✧ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴ ✚ ✛ ✣ ✤ ✂ ✥ ✢ ✦ ✧ ☎ ★ ✬ ✩ ✄ ✪ ✁ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴

Searching over Metapositions in Kriegspiel – p.8/34

slide-66
SLIDE 66

PaoloC-Krieg, ICC Aprile 2003

Searching over Metapositions in Kriegspiel – p.8/34

slide-67
SLIDE 67

Example of position (1/3)

✚ ✁ ✣ ✥ ✦ ✧ ★ ✩ ✪ ✭ ✮ ✯ ✰ ✱ ✲ ✳ ✴
  • This diagram shows an example of position

during a game of

ending;

  • the game tree has a branch of 11 moves,

corresponding to the possible White’s moves,

  • plus the Black’s ones.

Searching over Metapositions in Kriegspiel – p.9/34

slide-68
SLIDE 68

Example of position (2/3)

  • Black’s choices compose the information sets for White,

who does not know where Black has moved his pieces;

  • In the example seen before we have to deal with 33

information sets for White and 53 positions in total

8

✶ ✶ ✶ ✷ ✶

7

✶ ✶ ✶ ✸

6

✶ ✶ ✶ ✶

5

✶ ✶ ✶ ✹

4

✶ ✶ ✶ ✶

3

✶ ✶ ✶ ✶

2

✶ ✶ ✶ ✶

1

✶ ✶ ✶ ✶

a b c d e f g h 8

✷ ✶ ✶ ✶ ✶

7

✶ ✶ ✶ ✸

6

✶ ✶ ✶ ✶

5

✶ ✶ ✶ ✺ ✶ ✺

4

✶ ✶ ✹ ✺ ✹

3

✶ ✶ ✶ ✶

2

✶ ✶ ✶ ✶

1

✶ ✶ ✶ ✶

a b c d e f g h

(×5)

8

✶ ✶ ✻ ✶

7

✶ ✶ ✶ ✸

6

✶ ✶ ✶ ✶

5

✶ ✶ ✶ ✶ ✺

4

✶ ✶ ✶ ✺ ✹

3

✶ ✶ ✶ ✶

2

✶ ✶ ✶ ✶

1

✶ ✶ ✶ ✶

a b c d e f g h 8

✶ ✶ ✶ ✻

7

✶ ✶ ✶ ✸

6

✶ ✶ ✶ ✶

5

✶ ✶ ✶ ✺ ✶

4

✶ ✶ ✹ ✺ ✶

3

✶ ✶ ✶ ✶

2

✶ ✶ ✶ ✶

1

✶ ✶ ✶ ✶

a b c d e f g h 8

✶ ✶ ✸ ✷ ✶

7

✶ ✶ ✶ ✶

6

✶ ✶ ✹ ✹

5

✶ ✶ ✶ ✺ ✶ ✺

4

✶ ✶ ✹ ✹

3

✶ ✶ ✶ ✶

2

✶ ✶ ✶ ✶

1

✶ ✶ ✶ ✶

a b c d e f g h 8

✶ ✶ ✶ ✷ ✸

7

✶ ✶ ✶ ✶

6

✶ ✶ ✹ ✹

5

✶ ✶ ✶ ✺ ✶ ✺

4

✶ ✶ ✹ ✹

3

✶ ✶ ✶ ✶

2

✶ ✶ ✶ ✶

1

✶ ✶ ✶ ✶

a b c d e f g h 8

✶ ✶ ✶ ✷ ✶

7

✶ ✶ ✶ ✼ ✶

6

✶ ✶ ✶ ✹

5

✶ ✶ ✶ ✺ ✶ ✺

4

✶ ✶ ✹ ✹

3

✶ ✶ ✶ ✶

2

✶ ✶ ✶ ✶

1

✶ ✶ ✶ ✶

a b c d e f g h 8

✶ ✶ ✶ ✷ ✶

7

✶ ✶ ✶ ✶ ✼

6

✶ ✶ ✹ ✶

5

✶ ✶ ✶ ✺ ✶ ✺

4

✶ ✶ ✹ ✹

3

✶ ✶ ✶ ✶

2

✶ ✶ ✶ ✶

1

✶ ✶ ✶ ✶

a b c d e f g h

a8 (×5)

f8

h8

f8

h8

f7

h7

  • g4 h4 f4 f5 h5
  • g4

h4 h5

  • f5

f4 g4

  • f5

h5 f4 h4 f6 h6

  • f5

h5 f4 h4 f6 h6

  • f4

h4 f5 h5 h6

  • f4

h4 f5 h5 f6

Searching over Metapositions in Kriegspiel – p.10/34

slide-69
SLIDE 69

Example of position (3/3)

Considering White moves

f8:

  • Black’s possible moves are

h5,

h4 or

g4;

  • White now faces two information sets of 2 and 1

elements respectively:

  • The former includes 21 possible moves,
  • the latter includes 19 moves
  • the game tree branches out with

2 · 21 + 19 = 61

further nodes We aim to obtain a tree without information sets with more than an element.

Searching over Metapositions in Kriegspiel – p.11/34

slide-70
SLIDE 70

Using metapositions

We could join the moves made by Black which lead to the same information set:

f8 Black White White

g4

h5

h4

x7

x14 x

x7

x14 y

x5

x14 z

Searching over Metapositions in Kriegspiel – p.12/34

slide-71
SLIDE 71

Using metapositions

We could join the moves made by Black which lead to the same information set:

f8 Black White White

g4∧

h4

h5

x7

x14 x′ ≃ min(x, y)

x5

x14 z

Searching over Metapositions in Kriegspiel – p.12/34

slide-72
SLIDE 72

Using metapositions

We could join the moves made by Black which lead to the same information set:

f8 Black White White

g4∧

h4

h5

x7

x14 x′ ≃ min(x, y)

x5

x14 z

Because of the complexity of a procedure which distinguishes between Black’s moves that lead to different information sets for White we define the game tree in a simpler but equivalent

Searching over Metapositions in Kriegspiel – p.12/34

slide-73
SLIDE 73

Metapositions

  • Metaposition: is a particular position which describes a

set of positions.

  • Metamove: a move by Black player from one

metaposition to another.

  • Pseudomove: a move by White player on a

metaposition.

❈ ❉ ❊ ❊ ❊ ❊ ❋ ❊
❊ ❊ ❍ ❊ ❊ ❊ ❊ ■ ❊ ❊ ❊ ❏ ❑ ❊ ❊ ❊ ❊ ▲ ❊ ❊ ❊ ❊ ▼ ❊ ❊ ❊ ◆ ❊ ❖ ❊ ❊ ❊ ❊ P ◗ ❘ ❙ ❚ ❯ ❱ ❲

Searching over Metapositions in Kriegspiel – p.13/34

slide-74
SLIDE 74

Metapositions

  • Metaposition: is a particular position which describes a

set of positions.

  • Metamove: a move by Black player from one

metaposition to another.

  • Pseudomove: a move by White player on a

metaposition.

❳ ❨ ❩ ❩ ❩ ❩ ❬ ❩ ❭ ❩ ❩ ❩ ❪ ❩ ❩ ❫ ❴ ❫ ❵ ❩ ❩ ❩ ❴ ❩ ❴ ❛ ❩ ❩ ❫ ❴ ❫ ❜ ❩ ❩ ❩ ❴ ❫ ❴ ❝ ❩ ❩ ❫ ❫ ❞ ❩ ❩ ❩ ❴ ❫ ❴ ❡ ❢ ❣ ❤ ✐ ❥ ❦ ❧

Searching over Metapositions in Kriegspiel – p.13/34

slide-75
SLIDE 75

Metapositions

  • Metaposition: is a particular position which describes a

set of positions.

  • Metamove: a move by Black player from one

metaposition to another.

  • Pseudomove: a move by White player on a

metaposition.

♠ ♥ ♥ ♥ ♥ ♦ ♥ ♣ ♥ ♥ ♥ q ♥ ♥ r s r t ♥ ♥ ♥ s ♥ s ✉ ✈ ♥ ♥ ♥ ♥ ✇ ♥ ♥ ♥ s r s ① ♥ ♥ r r ② ♥ ♥ ♥ s r s ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ⑩

Searching over Metapositions in Kriegspiel – p.13/34

slide-76
SLIDE 76

Cardinality of pseudomoves

  • The set P of pseudomoves has a cardinality equal to the

maximum cardinality of legal moves for each position.

|P| = max(|legal moves|)

  • For the example seen before White always considers 21

pseudomoves, even if he is in the case with 19 legal moves, because he cannot distinguish between the two situations.

Searching over Metapositions in Kriegspiel – p.14/34

slide-77
SLIDE 77

The game tree

❶ ❷ ❷ ❸ ❷ ❹ ❷ ❷ ❷ ❺ ❻ ❷ ❷ ❷ ❷ ❼ ❷ ❷ ❷ ❷ ❽ ❾ ❷ ❷ ❷ ❽ ❿ ➀ ❷ ❷ ❷ ❷ ➁ ❷ ❷ ❷ ❷ ➂ ❷ ❷ ❷ ❷ ➃ ➄ ➅ ➆ ➇ ➈ ➉ ➊ ➋

x7

x14 pseudomoves

Searching over Metapositions in Kriegspiel – p.15/34

slide-78
SLIDE 78

The game tree

➍ ➎ ➎ ➏ ➎ ➐ ➎ ➎ ➎ ➑ ➒ ➎ ➎ ➎ ➎ ➓ ➎ ➎ ➎ ➎ ➔ → ➎ ➎ ➎ ➔ ➣ ↔ ➎ ➎ ➎ ➎ ↕ ➎ ➎ ➎ ➎ ➙ ➎ ➎ ➎ ➎ ➛ ➜ ➝ ➞ ➟ ➠ ➡ ➢ ➤

x7 . . . . . . .

x14 pseudomoves S C I S C I x y z x′ y′ z′

Searching over Metapositions in Kriegspiel – p.15/34

slide-79
SLIDE 79

The game tree

➦ ➧ ➧ ➨ ➧ ➩ ➧ ➧ ➧ ➫ ➭ ➧ ➧ ➧ ➧ ➯ ➧ ➧ ➧ ➧ ➲ ➳ ➧ ➧ ➧ ➲ ➵ ➸ ➧ ➧ ➧ ➧ ➺ ➧ ➧ ➧ ➧ ➻ ➧ ➧ ➧ ➧ ➼ ➽ ➾ ➚ ➪ ➶ ➹ ➘ ➴

x7 . . . . . . .

x14 pseudomoves S C I S C I x ≤ y ≤ z x′ ≥ y′ ≤ z′

Searching over Metapositions in Kriegspiel – p.15/34

slide-80
SLIDE 80

Exploiting the referee’s answers

8

➬ ➮ ➬ ➮ ➬ ➱ ➬ ➮

7

➮ ➬ ➮ ➬ ➮ ➮ ➬

6

➬ ➱ ➱ ➬ ➱ ➬ ➮

5

➮ ✃ ➮ ➮ ➬

4

➬ ➱ ➱ ➬ ➱ ➬ ➮

3

➱ ➱ ➱ ❐ ➱

2

➬ ➮ ➬ ➮ ➬ ➱ ➬ ➮

1

➮ ➬ ➮ ➬ ➮ ➮ ➬

a b c d e f g h

e3 silent: we clean the squares around the King and along row and column

Searching over Metapositions in Kriegspiel – p.16/34

slide-81
SLIDE 81

Exploiting the referee’s answers

8

❒ ❮ ❒ ❮ ❰ ❒ ❮

7

❮ ❒ ❮ ❒ ❰ ❮ ❒

6

❒ ❰ ❰ ❰ ❒ ❮

5

❮ Ï ❰ ❮ ❒

4

❒ ❰ ❰ ❰ ❒ ❮

3

❰ ❰ Ð ❰

2

❒ ❮ ❒ ❮ ❰ ❒ ❮

1

❮ ❒ ❮ ❒ ❰ ❮ ❒

a b c d e f g h

e3 silent: we clean the squares around the King and along row and column

Searching over Metapositions in Kriegspiel – p.16/34

slide-82
SLIDE 82

Exploiting the referee’s answers

8

Ñ Ò Ñ Ò Ó Ñ Ò

7

Ò Ñ Ò Ñ Ó Ò Ñ

6

Ñ Ó Ó Ó Ñ Ò

5

Ò Ô Ó Ò Ñ

4

Ñ Ó Ó Ó Ñ Ò

3

Ó Ó Õ Ó

2

Ñ Ò Ñ Ò Ó Ñ Ò

1

Ò Ñ Ò Ñ Ó Ò Ñ

a b c d e f g h

e3 silent: we clean the squares around the King and along row and column

8

Ö × Ö × Ö Ø Ö ×

7

× Ö × Ö × × Ö

6

Ö Ø Ø Ö Ø Ö ×

5

× Ù × × Ö

4

Ö Ø Ø Ö Ø Ö ×

3

Ø Ø Ø Ú Ø

2

Ö × Ö × Ö Ø Ö ×

1

× Ö × Ö × × Ö

a b c d e f g h

e3 check: we clean all the squares and we assume that the King is on the row or column

Searching over Metapositions in Kriegspiel – p.16/34

slide-83
SLIDE 83

Exploiting the referee’s answers

8

Û Ü Û Ü Ý Û Ü

7

Ü Û Ü Û Ý Ü Û

6

Û Ý Ý Ý Û Ü

5

Ü Þ Ý Ü Û

4

Û Ý Ý Ý Û Ü

3

Ý Ý ß Ý

2

Û Ü Û Ü Ý Û Ü

1

Ü Û Ü Û Ý Ü Û

a b c d e f g h

e3 silent: we clean the squares around the King and along row and column

8

à à á à à

7

à à â à

6

à à á à à

5

à ã â à

4

à à á à à

3

à à ä à

2

à à á à à

1

à à â à

a b c d e f g h

e3 check: we clean all the squares and we assume that the King is on the row or column

Searching over Metapositions in Kriegspiel – p.16/34

slide-84
SLIDE 84

Exploiting the referee’s answers

8

å æ å æ ç å æ

7

æ å æ å ç æ å

6

å ç ç ç å æ

5

æ è ç æ å

4

å ç ç ç å æ

3

ç ç é ç

2

å æ å æ ç å æ

1

æ å æ å ç æ å

a b c d e f g h

e3 silent: we clean the squares around the King and along row and column

8

ê ê ë ê ê

7

ê ê ì ê

6

ê ê ë ê ê

5

ê í ì ê

4

ê ê ë ê ê

3

ê ê î ê

2

ê ê ë ê ê

1

ê ê ì ê

a b c d e f g h

e3 check: we clean all the squares and we assume that the King is on the row or column

8

ï ð ï ð ï ñ ï ð

7

ð ï ð ï ð ð ï

6

ï ñ ñ ï ñ ï ð

5

ð ò ð ð ï

4

ï ñ ñ ï ñ ï ð

3

ñ ñ ñ ó ñ

2

ï ð ï ð ï ñ ï ð

1

ð ï ð ï ð ð ï

a b c d e f g h

Kd5 illegal: we clean all the squares

  • nly leaving those around the Black King%

Searching over Metapositions in Kriegspiel – p.16/34

slide-85
SLIDE 85

Exploiting the referee’s answers

8

ô õ ô õ ö ô õ

7

õ ô õ ô ö õ ô

6

ô ö ö ö ô õ

5

õ ÷ ö õ ô

4

ô ö ö ö ô õ

3

ö ö ø ö

2

ô õ ô õ ö ô õ

1

õ ô õ ô ö õ ô

a b c d e f g h

e3 silent: we clean the squares around the King and along row and column

8

ù ù ú ù ù

7

ù ù û ù

6

ù ù ú ù ù

5

ù ü û ù

4

ù ù ú ù ù

3

ù ù ý ù

2

ù ù ú ù ù

1

ù ù û ù

a b c d e f g h

e3 check: we clean all the squares and we assume that the King is on the row or column

8

þ þ þ þ

7

þ þ þ þ

6

þ þ ÿ þ þ

5

þ
þ

4

þ þ ÿ þ þ

3

þ þ þ ✂ þ

2

þ þ þ þ

1

þ þ þ þ

a b c d e f g h

d5 illegal: we clean all the squares leaving those around the

Searching over Metapositions in Kriegspiel – p.16/34

slide-86
SLIDE 86

The search algorithm

  • Moves that jeopardize important pieces are pruned;
  • recently-played moves are not played in direct sequence;
  • the search algorithm uses:
  • a static evaluation function:
  • to enable the algorithm to prune bad moves;
  • to enable the algorithm to choose one of the

three referee’s answers;

  • a recursive evaluation function:
  • it is returned by the recursive call during the tree

visit.

  • The value of a metaposition is obtained by adding the

recursive value to the static value.

Searching over Metapositions in Kriegspiel – p.17/34

slide-87
SLIDE 87

Searching through metapositions

✄ ✄ ✄ ☎ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✝ ✄ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✝ ✄ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✝ ✆ ✄ ✆ ✝ ✆ ✝ ✆ ✝ ✄ ✞

Searching over Metapositions in Kriegspiel – p.18/34

slide-88
SLIDE 88

Searching through metapositions

✟ ✟ ✟ ✠ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ☛ ✟ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ☛ ✟ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ☛ ✡ ✟ ✡ ☛ ✡ ☛ ✡ ☛ ✟ ☞ ✟ ✟ ✟ ✌ ✟ ✡ ☛ ✡ ☛ ✡ ☛ ✟ ☛ ✡ ☛ ✡ ☛ ✡ ✟ ✡ ☛ ✡ ☛ ✡ ☛ ✟ ☛ ✡ ☛ ✡ ☛ ✡ ✟ ✡ ☛ ✡ ☛ ✡ ☛ ✟ ☛ ✡ ☛ ✡ ☛ ✡ ✟ ✡ ☛ ✡ ☛ ✡ ☛ ✟ ☞

,−526

g8 . . .

Searching over Metapositions in Kriegspiel – p.18/34

slide-89
SLIDE 89

Searching through metapositions

✎ ✎ ✎ ✏ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✒ ✎ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✒ ✎ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✒ ✑ ✎ ✑ ✒ ✑ ✒ ✑ ✒ ✎ ✓ ✎ ✎ ✎ ✔ ✎ ✑ ✒ ✑ ✒ ✑ ✒ ✎ ✒ ✑ ✒ ✑ ✒ ✑ ✎ ✑ ✒ ✑ ✒ ✑ ✒ ✎ ✒ ✑ ✒ ✑ ✒ ✑ ✎ ✑ ✒ ✑ ✒ ✑ ✒ ✎ ✒ ✑ ✒ ✑ ✒ ✑ ✎ ✑ ✒ ✑ ✒ ✑ ✒ ✎ ✓

313,313 . . . 272,272

g1

g2

g8 . . . ,−526

Searching over Metapositions in Kriegspiel – p.18/34

slide-90
SLIDE 90

Searching through metapositions

✖ ✖ ✖ ✗ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✙ ✖ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✙ ✖ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✙ ✘ ✖ ✘ ✙ ✘ ✙ ✘ ✙ ✖ ✚ ✖ ✖ ✖ ✛ ✖ ✘ ✙ ✘ ✙ ✘ ✙ ✖ ✙ ✘ ✙ ✘ ✙ ✘ ✖ ✘ ✙ ✘ ✙ ✘ ✙ ✖ ✙ ✘ ✙ ✘ ✙ ✘ ✖ ✘ ✙ ✘ ✙ ✘ ✙ ✖ ✙ ✘ ✙ ✘ ✙ ✘ ✖ ✘ ✙ ✘ ✙ ✘ ✙ ✖ ✚

313,313 . . . 272,272

g1

g2

g8 . . . −213,−526

Searching over Metapositions in Kriegspiel – p.18/34

slide-91
SLIDE 91

Searching through metapositions

✢ ✢ ✢ ✣ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✢ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✢ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✢ ✤ ✥ ✤ ✥ ✤ ✥ ✢ ✦ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✢ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✢ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✥ ✢ ✤ ✥ ✤ ✥ ✤ ✥ ✤ ✢ ✢ ✢ ✣ ✤ ✥ ✤ ✥ ✤ ✥ ✢ ✦

,262

✢ ✢ ✢ ✧ ✢ ✤ ✥ ✤ ✥ ✤ ✥ ✢ ✥ ✤ ✥ ✤ ✥ ✤ ✢ ✤ ✥ ✤ ✥ ✤ ✥ ✢ ✥ ✤ ✥ ✤ ✥ ✤ ✢ ✤ ✥ ✤ ✥ ✤ ✥ ✢ ✥ ✤ ✥ ✤ ✥ ✤ ✢ ✤ ✥ ✤ ✥ ✤ ✥ ✢ ✦

313,313 . . . 272,272

g1

g2

h2

g8 . . . . . . . . . −213,−526

Searching over Metapositions in Kriegspiel – p.18/34

slide-92
SLIDE 92

Searching through metapositions

✩ ✩ ✩ ✪ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✩ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✩ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✩ ✫ ✬ ✫ ✬ ✫ ✬ ✩ ✭ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✩ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✩ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✬ ✩ ✫ ✬ ✫ ✬ ✫ ✬ ✫ ✩ ✩ ✩ ✪ ✫ ✬ ✫ ✬ ✫ ✬ ✩ ✭ ✩ ✩ ✩ ✮ ✩ ✫ ✬ ✫ ✬ ✫ ✬ ✩ ✬ ✫ ✬ ✫ ✬ ✫ ✩ ✫ ✬ ✫ ✬ ✫ ✬ ✩ ✬ ✫ ✬ ✫ ✬ ✫ ✩ ✫ ✬ ✫ ✬ ✫ ✬ ✩ ✬ ✫ ✬ ✫ ✬ ✫ ✩ ✫ ✬ ✫ ✬ ✫ ✬ ✩ ✭

313,313 . . . 272,272

g1

g2 263,263 . . . 272,272

g2

g2

h2

g8 . . . . . . . . . −213,−526 534,262

Searching over Metapositions in Kriegspiel – p.18/34

slide-93
SLIDE 93

Searching through metapositions

✱ ✱ ✱ ✲ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✱ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✱ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✱ ✳ ✴ ✳ ✴ ✳ ✴ ✱ ✵ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✱ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✱ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✴ ✱ ✳ ✴ ✳ ✴ ✳ ✴ ✳ ✱ ✱ ✱ ✲ ✳ ✴ ✳ ✴ ✳ ✴ ✱ ✵ ✱ ✱ ✱ ✶ ✱ ✳ ✴ ✳ ✴ ✳ ✴ ✱ ✴ ✳ ✴ ✳ ✴ ✳ ✱ ✳ ✴ ✳ ✴ ✳ ✴ ✱ ✴ ✳ ✴ ✳ ✴ ✳ ✱ ✳ ✴ ✳ ✴ ✳ ✴ ✱ ✴ ✳ ✴ ✳ ✴ ✳ ✱ ✳ ✴ ✳ ✴ ✳ ✴ ✱ ✵

313 . . . 272

g1

g2 263 . . . 272

g2

g2

h2

g8 . . . . . . . . . 313 272

Searching over Metapositions in Kriegspiel – p.18/34

slide-94
SLIDE 94

The evaluation function

  • contains the notion of progress which leads the player

towards victory;

  • is a linear weighted sum of features

EVAL(m) = w1f1(m) + w2f2(m) + ... + wnfn(m) for example: w1 = −1, f1(s) = number of black kings;

  • returns the move which immediately gives Checkmate, if

it exists;

  • prunes moves that risk leading to a stalemate;
  • is different according to each single ending.

Searching over Metapositions in Kriegspiel – p.19/34

slide-95
SLIDE 95

The rook ending (

) (1/3)

The evaluation function for this ending considers n = 6 different features.

  • 1. it avoids jeopardizing the Rook: w1 = −1000 and f1 is a

boolean function which is true if white Rook is under attack;

  • 2. it brings the two Kings closer: w2 = −1 and f2 returns

the distance (number of squares) between the two Kings;

  • 3. it reduces the number of black Kings on the quadrants
  • f the board as seen from the Rook and it favors having

the black Kings grouped together in as few quadrants as possible: w3 = −1 and f3 = c

4

i=1 qi where

c ∈ {1, 2, 3, 4} is a constant which counts the quadrants

that contains a black King and qi counts the number of possible black Kings on ith quadrant;

Searching over Metapositions in Kriegspiel – p.20/34

slide-96
SLIDE 96

The rook ending (

) (2/3)

4. it avoids the black King to go between white Rook and white King: w5 = −500 and f5 is a boolean function which returns true if the black King is inside the rectangle formed by white King and white Rook on two

  • pposite corners;

5. it keeps White pieces close to each other: w5 = +1 and

f5 is a boolean function which returns true if the Rook is

adjacent to the King; 6. it pushes the black King toward the corner of the board:

w6 = +1 and f6 =

63

i=0 v[i], where v is a numerical

64-element vector, shown in the following slide, that returns a grade for each squares which possibly holds the black King or returns 0 otherwise.

Searching over Metapositions in Kriegspiel – p.21/34

slide-97
SLIDE 97

The rook ending (

) (3/3)

The simple numerical matrix v[] used in the 6th features:

                  1 1 1 1 1 1 −2 −4 −4 −2 −4 −4 −4 −4 −4 −4 −4 −4 −2 −4 −4 −2 1 1 1 1 1 1                  

Searching over Metapositions in Kriegspiel – p.22/34

slide-98
SLIDE 98

Histogram of

ending

This histogram represents the number of moves needed to win each game, starting from metapositions with greatest uncertainty.

Searching over Metapositions in Kriegspiel – p.23/34

slide-99
SLIDE 99

The queen ending (

)

  • 7. it avoids metapositions where Queen risks to be

captured: w7 = −100 and f7 is a boolean function that returns true if Queen is under attack;

  • 8. it penalizes those metapositions with a big number of

black Kings: w8 = −1 and f8 is equal to the number of black Kings on White’s reference board;

  • 9. it reduces the number of black Kings on the areas traced

by the Queen’s diagonals: w9 = −1 and

f9 = evalRhombArea(S) where evalRhombArea(S) = c · (a0 + a1 + a2 + a3)

(0) and c ∈ {1, 2, 3, 4} is a constant which counts the areas that possibly contains a black King and ai (i = 0, ..., 3) counts the number of possible black Kings on ith area.

Searching over Metapositions in Kriegspiel – p.24/34

slide-100
SLIDE 100

Description of evalRhombArea()

8

✹ ✺ ✹ ✻ ✹ ✺ ✹ ✻

7

✻ ✹ ✺ ✺ ✹ ✻ ✹

6

✹ ✻ ✹ ✻ ✹ ✻ ✹ ✺

5

✺ ✹ ✻ ✻ ✹ ✺ ✹

4

✻ ✼ ✻ ✻

3

✺ ✹ ✻ ✻ ✹ ✺ ✹

2

✹ ✻ ✹ ✻ ✻ ✹ ✺

1

✻ ✹ ✺ ✽ ✻ ✹

a b c d e f g h 8

✻ ✻ ✻ ✻

7

✻ ✻ ✻ ✻

6

✻ ✻ ✻ ✻

5

✻ ✻ ✻ ✻

4

✻ ✼ ✻ ✻

3

✻ ✻ ✻ ✻

2

✻ ✻ ✻ ✻

1

✻ ✻ ✽ ✻

a b c d e f g h

a0 a1 a2 a3

  • Miniature on the right shows the 4 different areas if the

queen is on d4;

  • miniature on the left represents a metaposition with

greatest uncertainty: in this case the function returns

4 · (12 + 12 + 3 + 6) = 132.

Searching over Metapositions in Kriegspiel – p.25/34

slide-101
SLIDE 101

Histogram of

ending

This histogram represents the number of moves needed to win each game, starting from metapositions with greatest uncertainty.

Searching over Metapositions in Kriegspiel – p.26/34

slide-102
SLIDE 102

The ending with two Bishops (

✬ ✂

)

The evaluation function exploits the same subfunctions previously analyzed, but it assigns different weights:

  • 1. it avoids jeopardizing the Bishop: w1 = −1000 and f1 is

a boolean function which is true if white Bishop is under attack;

  • 2. it brings the two Kings closer: w2 = −1 and f2 returns

the distance (number of squares) between the two Kings;

  • 3. it avoids the black King to ”

pass through”the border controlled by the Bishops: w3 = −500 and f3 is a boolean function which returns true if the black King is inside the rectangle formed by King and Bishop row or King and Bishop column;

  • 4. it keeps close the white Bishops: w4 = +2 and f4 is a

boolean function which returns true if the Bishops are adjacent to each other;

Searching over Metapositions in Kriegspiel – p.27/34

slide-103
SLIDE 103

The ending with two Bishops (

✬ ✂

)

5. it pushes the black King toward the corner of the board:

w5 = +1 and f5 =

63

i=0 b[i], where b is a numerical

64-element vector, shown in figure, that returns a grade for each squares which possibly holds the black King or returns 0 otherwise.

             

−10 −50 −100 −100 −50 −10 −10 −10 −40 −40 −40 −40 −10 −10 −50 −40 −40 −40 −40 −40 −40 −50 −100 −40 −40 −50 −50 −40 −40 −100 −100 −40 −40 −50 −50 −40 −40 −100 −50 −40 −40 −40 −40 −40 −40 −50 −10 −10 −40 −40 −40 −40 −10 −10 −10 −50 −100 −100 −50 −10

             

Searching over Metapositions in Kriegspiel – p.28/34

slide-104
SLIDE 104

The ending with two Bishops (

✬ ✂

)

6. it keeps white King on the Bishop’s row or column:

w6 = +1and f6 is a boolean function which returns true

if the King and the Bishop are on the same row or column; 7. it penalizes the metapositions where the Bishop risks to be captured: w7 = −100 and f7 is a boolean function that returns true if Bishops are under attack; 8. it penalizes the metapositions with a big number of black Kings: w8 = −1 and f8 is equal to the number of black Kings on White’s reference board; 9. it reduces the number of black Kings on the areas traced by the Bishop’s diagonals: f9 = evalRhombArea(m), and if evalRhombArea(m) < −600 w9 = −4;

  • therwise w9 = 1

6

Searching over Metapositions in Kriegspiel – p.29/34

slide-105
SLIDE 105

The ending with two Bishops (

✬ ✂

)

10. it prefers some particular positioning (we will refer to with the term key Bishops’ positions) for the white King and Bishops, highlighted in figure; for example

  • c7,

c4 and

  • c5. Therefore w10 = +30 and f10 is a

boolean function which is true if the Bishops and the King are arranged in one of the key positions.

8

✾ ✾ ✾ ✾

7

✾ ✿ ✾ ❀ ✾

6

✿ ❁ ❂ ✾ ❀ ✾

5

✾ ❁ ✾ ❂ ✾

4

✾ ❂ ✾ ❁ ✾

3

✾ ❀ ✾ ❂ ❁ ✿

2

✾ ❀ ✾ ✿ ✾

1

✾ ✾ ✾ ✾

a b c d e f g h 8

❃ ✾ ✾ ✾ ✾

7

❄ ✿ ✾ ✾

6

✾ ✾ ✾ ✾

5

✾ ✾ ✾ ✾

4

✾ ❂ ✾ ✾ ✾

3

✾ ✾ ✾ ✾

2

✾ ✾ ✾ ✾

1

✾ ✾ ✾ ✾

a b c d e f g h 8

❃ ✾ ✾ ✾ ✾

7

✾ ✿ ✾ ✾

6

✾ ✾ ✾ ✾

5

✾ ❁ ✾ ✾

4

✾ ❂ ✾ ✾ ✾

3

✾ ✾ ✾ ✾

2

✾ ✾ ✾ ✾

1

✾ ✾ ✾ ✾

a b c d e f g h 8

❃ ✾ ✾ ✾ ✾

7

✾ ✿ ✾ ✾

6

✾ ✾ ✾ ✾

5

✾ ❁ ❂ ✾ ✾

4

✾ ✾ ✾ ✾

3

✾ ✾ ✾ ✾

2

✾ ✾ ✾ ✾

1

✾ ✾ ✾ ✾

a b c d e f g h

Searching over Metapositions in Kriegspiel – p.30/34

slide-106
SLIDE 106

Histogram of

✬ ✂

ending

This histogram represents the number of moves needed to win each game, starting from random metapositions with greatest uncertainty.

Searching over Metapositions in Kriegspiel – p.31/34

slide-107
SLIDE 107

The pawn ending (

)

  • 1. it brings the Pawn adjacent to the King: w1 = −1 and

f1 calculates the distance between King and Pawn;

  • 2. it pushes the Pawn: w2 = +1 and f2 = 2 · (Pawn′srow);
  • 3. it let the King above the Pawn: w3 = +1 and

f3 = (King′srow) − (Pawn′srow);

  • 4. If (Pawn′s row == seventh row)

if (Pawn′s row) > (King′s row) w4 = −1000;

  • therwise w4 = +100
  • 5. If (Pawn′s row == sixth row)

if (King is on the right of the Pawn)

w5 = +5 + rand();

if (King is on the left of the Pawn)

w5 = +5 + rand();

Searching over Metapositions in Kriegspiel – p.32/34

slide-108
SLIDE 108

Histogram of

ending

This histogram represents the number of moves needed to win each game, starting from random metapositions with greatest uncertainty.

Searching over Metapositions in Kriegspiel – p.33/34

slide-109
SLIDE 109

Conclusion

  • In our knowledge this is the first time that an evaluation

function including a notion of progress has been defined for Kriegspiel.

  • We have devoted special care to implement progress

inside such an evaluation function.

  • We have tested such a function on some simple endings,

with good results except for the KBN vs K case.

  • Future work will lead us to adapt the program to more

complex endings, where both players have a larger number of pieces on the board.

  • Our aim consists in writing a complete program for the

whole game of Kriegspiel.

Searching over Metapositions in Kriegspiel – p.34/34