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Cube Reference Positions

Cube Reference Positions

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Cube Reference Positions

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  1. Cube Reference Positions Sean Williams, Backgammon Live in London, 2010

  2. Contents • Why Cube Reference Positions? • The Blitz (Mostly Woolsey); • Anchor Games (Woolsey); • Priming Games (Cohn-Geier); • 1 Man Back Verses 2 Men Back; • Made 5-points; • Further Reading and References

  3. Why Cube Reference Positions? • Most positions in backgammon are not directly calculable; • Our intuitions can be very wrong in many situations (if we have an intuition at all); • Backgammon is a subtle game where small changes to a position can have a big effect; • Reference positions ground our thinking and give us the foundations for improving our game.

  4. Key Factors in Blitz Cube Decisions • Number of Attackers Home Board Points; • Number of Checkers On the Bar; • Number of Checkers 'In the Zone'; • Distribution of attacking checkers; • Opponent's blots; • Attacker's back checkers; • Defender's Home Board.

  5. The Blitz • Common Positions; • Borderline References.

  6. Common Blitz Positions

  7. 64R 55P Dance Cube Action? Double/Take (0.845)

  8. 64S 55P Dance Cube Action? Double/Pass (1.021)

  9. 52S 55P Dance Cube Action? Double/Pass (1.135)

  10. 51S 55P Dance Cube Action? No Double/Take (0.501)

  11. 43S 44K Dance Cube Action? Double/Pass (1.018)

  12. 41S 44K Dance Cube Action? Double/Take (0.905)

  13. Borderline Blitz Positions

  14. 33 Structure, 9 in Zone, 1 on Bar Cube Action? Double/Pass (1.03)

  15. 55 Structure, 10 in Zone, 1 on Bar Cube Action? Double/Pass (1.03)

  16. 4 Point Board, 8 in Zone, 1 on Bar Cube Action? Double/Pass (1.01)

  17. 2 Point Board, 10 in Zone, 2 on Bar Cube Action? Double/Pass (1.12)

  18. Key Factors in Anchor Games Cube Decisions • Which anchor the defender holds; • The race; • The defenders defensive position; • Landing spots for the attacker; • Attacker's spares.

  19. Standard 5-point holding game, 20 pip race lead Double/Take (0.721)

  20. 5-point holding game, no spares, 20 pip race lead No Double/Take (0.638)

  21. 5-point holding game, made bar, 20 pip race lead Double/Take (0.957)

  22. 5-point holding game, made bar, 30 pip race lead Double/Pass (1.121)

  23. Standard 4-point holding game, 20 pip race lead Double/Take (0.747)

  24. 4-point holding game, full prime, 4 pip race lead No Double/Take (0.685)

  25. Standard 3-point game, 20 pip race lead Double/Take (0.885)

  26. 3-point game, made bar, 10 pip race lead Double/Pass (1.021)

  27. 3-point game, 15 pip race deficit, opp 4-point board Double/Pass (1.126)

  28. 3-point game, 10 pip race deficit, opp 5-point board Double/Take (0.924)

  29. Standard 2-point game, 20 pip race lead Double/Pass (1.135)

  30. 2-point game, 20 pip race lead, no 8-point Double/Take (0.986)

  31. 2-point game, 20 pip race lead, no 3-point Double/Take (0.943)

  32. 2-point game, 30 pip race lead, checker on ace Double/Take (0.989)

  33. 2-point game, 30 pip race lead, checker on ace, all rolls play Double/Pass (1.191)

  34. 2-point game, 36 pip race lead, 2 checkers on ace Double/Take (0.964)

  35. Standard ace-point game, 30 pip race lead Double/Pass (1.452)

  36. Ace-point game, 10 pip race lead, no 2 or 3-point Double/Pass (1.063)

  37. Key Factors in Priming Games • Length of Prime; • Time to escape; • Number of checkers behind the prime; • Position of the checkers behind the prime.

  38. 1 checker at the edge of a 5-prime, spare pip count of 6 Bare Double/Take (0.130)

  39. 1 checker at the edge of a 5-prime, spare pip count of 7 Double/Take (0.168)

  40. 1 checker at the edge of a 5-prime, spare pip count of 7 (61) No Double/Beaver (-0.096)

  41. 1 checker at the edge of a 5-prime, spare pip count of 9 Borderline Redouble (0.363)

  42. 1 checker at the edge of a 5-prime, spare pip count of 20 Redouble/Pass (1.007)

  43. 2 checkers at the edge of a 5-prime, 2 on bar, spare pip count of 18 Double/Take (0.929)

  44. 2 checkers at the edge of a 5-prime, 2 on bar, spare pip count of 12 Borderline No Redouble (0.477)

  45. Key Factors in 1 Man Back Vs 2 Men Back • Number of Attackers Home Board Points; • Number of Defenders Home Board Points; • The Race; • Relative Structures; • Blitzing/Priming Potential.

  46. 1 Man Back, 20 pip race lead, made 5-point Borderline No Double (0.811)

  47. 1 Man Back, 20 pip race lead, made 5-point and 9-point Double/Pass (1.012)

  48. 1 Man Back, 20 pip race lead, made 5 and 9-point, opp has 5-point Borderline No Double (0.712)

  49. Made 5-points Position A No Double/Take (0.724)

  50. Made 5-points Position B Double/Take (0.904)