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SMITH and JONES: Two puzzles

Posted By: Nack Ballard
Date: Tuesday, 14 March 2017, at 10:25 p.m.

The original SMITH and JONES post relays a story that at first seems impossible. Two players, playing the checkers and cube perfectly throughout, start from the opening position and later re-reach the opening position in as few as 109 rolls (55 by one player and 54 by the other) with the cube having been turned 64 times.

It turns out to be possible, as is demonstrated in two posts: SMITH and JONES: The Emperor's Chessboard, and SMITH and JONES: The Journey Home. Midway through the game (shown as the last position in the first of those posts, and as the first position in the second post), the two players reach a FARE position, which is diagrammed below [except that I've re-centered (removed) the cube, which is irrelevant for this post].






White is Player 2

score: 0
pip: 166

Unlimited Game
pip: 166
score: 0

Blue is Player 1
XGID=aa-a-ADACA--bB--acada-A-AA:0:0:1:00:0:0:3:0:10

I offer two puzzles based on the above position.

...Puzzle #1: From the opening position, reach the above position in fewer than 26 rolls.

...Puzzle #2: From the above position, re-reach the opening position in fewer than 20 rolls.

Smith and Jones did it with perfect play (i.e., #1 in 26 rolls, and #2 in 20 rolls). You only need to do it with LEGAL play. Standard backgammon rules apply, and therefore in Puzzle 1, the initial roll must be non-doublets. In Puzzle 2, that restriction does not apply. It makes no difference who rolls first, but for uniformity I suggest Blue.

For extra credit in one or both puzzles, accomplish the objective in as few rolls as possible.

Nack

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