tabula/DESIGN.md

Design

tabula is a multi-threaded backgammon analysis engine. To find the best move, the engine performs a series of simulations and scores the resulting game states. The result with the lowest score is the best move.

Scoring

Space value

Space value is defined as what the term 'pips' would normally refer to. The value of a space is the same as the space number as it would appear to the player being scored.

Pseudopips

All scoring calculations use pseudopips.

A pseudopip value is assigned to each board space as follows:

• Each space is worth 6 pseudopips plus double the space value.
• Spaces outside of the player's home board are worth an additional 6 pseudopips.

Space 2 (from the perspective of the player being scored) is therefore worth 10 pseudopips, space 6 is worth 18, space 7 is worth 26 and the bar space is worth 62.

Analysis

Step 1: Simulate all legal move available to the player

Step 2: Simulate all opponent dice rolls and opponent moves that may follow the above simulations

Step 3: Sort simulation results by score