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4 ply/XGR+/XGR++/Rollout
Posted By: Taper_Mike
Date: Wednesday, 30 October 2013, at 11:41 p.m.
In Response To: 4 ply/XGR+/XGR++/Rollout (Daniel Murphy)
You may be confusing evals with rollouts. XGR, XGR+, and XGR++ are called "evals," but actually each of them is a truncated rollout. When you use one of them in a rollout, a separate truncated rollout is made for every move in the full rollout. That explains why it can be so slow.
I have Rollouts a, b, and c set up in GnuBg to simulate XGR++. See my post:
Simulating XG Roller++ in GNU Backgammon
Here is the info from the XG Help system:
XGRoller
The XG Roller levels setting relies on truncated rollouts to estimate the position. This has been proven to be an extremely efficient way to analyze a position. For instance a level like XGRoller+ is much stronger but faster than a 5ply analysis.Here are the settings used for the different levels of XGRoller
XGRoller
42 Games using VR with rotation on 21 dice
Truncated after 5 moves using 1ply
All decisions in 1plyXGRoller+
360 games with VR
Truncated after 7 moves using 2ply
Stop when reaching 0.010 Confidence (minimum 180 games)
First 2 decision in 2ply
Then 1ply checker and 2ply cubeXGRoller++ Checker
360 games with VR
Truncated after 5 moves using 3ply
First 2 decisions in 3ply
Then 2ply checker and 3ply cubeXGRoller++ Cube
360 games with VR
Truncated after 7 moves using 3ply
Stop when reaching 0.010 Confidence (minimum 180 games)
First 2 decisions in 3ply
Then 2ply checker and 3ply cubeMike

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