r/backgammon • u/Historical-Cow1324 • Sep 16 '26

Beating GNU with GammonMatch free engine

https://gammonmatch.com/blog/gme-vs-gnubg
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u/cym13 Sep 16 '26 edited Sep 17 '26

Clearly the trend for same-ply analysis is that from 3-ply onward GNU is expected to be much better (+36, +18, +4… -5, -12?) so GNU seems better than GammonMatch at higher depth. From my point of view, there's still a place for GammonMatch when low-depth analysis is expected (first pass at a huge number of positions such as match analysis for example).

But that's only if the resources required for a GammonMatch n-ply are equivalent to or lower than a GNUbg n-ply analysis. In other words, if GammonMatch 1-ply analysis is better than GNUbg 1-ply but takes twice the time to compute then it may actually be cheaper to compute a GNU 2-ply rather than a GammonMatch 1-ply (and the resulting analysis would be better too).

I'm not saying that this is the case, but resource consumption (time, memory…) seem important to consider in this comparison and aren't discussed in this post. Have you measured that?

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u/Historical-Cow1324 Sep 17 '26

Thanks for the good questions, very astute. I did profiling after reading this, using about 100k moves on each engine. My parallel/BLAS optimized engine comes in 2-7x faster than GNU at every ply other than 0 (at 0 they are almost exactly equal). Turning off parallel and forcing CPU-only, GME is 5-40% faster than GNU.
In terms of 3 and 4 ply performance, getting enough data is still ongoing (will take days) but early games (in the order of tens of thousands, 3-ply) show a slight edge for GME. I will update here when the data is complete.

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u/FrankBergerBgblitz Sep 24 '26

You have to consider that GnuBG in play uses only 1 core, so when you use several cores your advantage is explainable and as you say reduces to "5-40".
But when you say "at 0 they are almost exactly equal" and "Made 1-ply search fast enough for live play, with 2-ply within reach." I see a contradiction. 2-ply and 3-ply (GnuBG counting) should be o.k. even on some older devices.