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BGonline.org Forums
XG vs. GNU rollout speed
Posted By: Timothy Chow
Date: Friday, 6 March 2015, at 3:33 p.m.
A couple of weeks ago, I suggested that XG rollouts are an order of magnitude faster than GNU rollouts, where by "order of magnitude" I meant "roughly a factor of ten." Philippe Michel responded:
I don't think the difference of speed is that large. The diagrams at http://extremegammon.com/studies.aspx#D2012 show a ratio of about 3.5 for analysis.
In practice, rollouts are likely to be done with the XG default setting that uses a narrower move filter for checker plays (faster) but XGR for cube decisions (slower).
A speed ratio of 3 to 4 still seems likely, 5 maybe, but 10 would be surprising.
Just this morning, I tried plugging in a relatively simple endgame decision. On my machine, XG took about 4 minutes. GNU, on the other hand, at first projected that it would take about an hour. I stopped it and looked at the settings, and found that it was using a supremo (large) move filter. When I changed that to world class (normal), the projected time dropped to about 40 minutes.
This would seem to vindicate my off-the-cuff claim, but before I do any more tests or study the rollout settings in more detail, I'm wondering if anyone else can corroborate these findings. In other words, do you find that if you do an XG 3-ply/XGR Normal rollout, it's around ten times faster than if you do a GNU world-class/world-class rollout?
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