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Re: [Bug-gnubg] Wrong luck adjusted result on Grandmaster analysis

From: Ian Shaw
Subject: Re: [Bug-gnubg] Wrong luck adjusted result on Grandmaster analysis
Date: Mon, 5 Jan 2015 14:17:25 +0000

Hi Richard.


The luck adjusted result looks OK to me.


You had -12.342% luck and tophat had +35.705% luck.

The actual result was you -50%, tophat +50%.


The Luck-Adjusted result formula = Actual Result – Own Luck + Opponent’s Luck.


Your luck-adjusted result = -50 - -12.342 + 35.705 = -1.953%

Tophat’s luck-adjusted result = 50 – 35.705 + -12.342 = -1.953%


In other words, without the luck, tophat would have got to 1.95% instead of +50%, and you would have got to -1.95% instead of -50%. His victory was almost entirely by luck.


You aren’t the first person to find this confusing.


If the formula were instead (50 – Own Luck + Opponent’s Luck), we would have got 98.05% and 1.95% in your favour.


May be it’s the Actual Result that is the source of the confusion. If this were reported as +100 and 0, rather than +50 and -50, the current formula  (Result – Own Luck + Opponent’s Luck), would give 48.05% and 51.95%. This indicates that, with the luck removed, your opponent only managed to get from 50% to 51.95%. Again, his victory was almost entirely luck.


I think that  (50 – Own Luck + Opponent’s Luck) gives the most intuitive result.


Does anyone know how the other two active bots, XG and BgBlitz, report the luck adjusted result? It might be sensible to standardize on a definition and use that. I’ve a feeling that XG uses (50 – Own Luck + Opponent’s Luck), but this is only based on my hazy recollection of the discussions at DailyGammon when Miran ran some luck-adjusted tournaments.


n  Ian


From: bug-gnubg-bounces+address@hidden [mailto:bug-gnubg-bounces+address@hidden On Behalf Of RICHARD BEAGLEY
Sent: 04 January 2015 16:08
To: address@hidden
Subject: [Bug-gnubg] Wrong luck adjusted result on Grandmaster analysis


Version GNU backgammon 0.90.0 Aug 8 2011


via XQuartz 2.7.7 (xoorg-server 1.15.2) on MAC OSX 10.6.8


Analysis - grandmaster 3 ply


This a single game result (3 point) with extreme differences in move, cube and luck ratings.  I should have had a luck adjusted win!


Is this a known bug and / or is my software out of date?




Richard Beagley (tregurtha)

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