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## Re: [Bug-gnubg] Re: Strange FIBS ratings

 From: Jim Segrave Subject: Re: [Bug-gnubg] Re: Strange FIBS ratings Date: Mon, 8 Sep 2003 15:03:55 +0200 User-agent: Mutt/1.4i

```On Mon 08 Sep 2003 (11:04 +0000), Joern Thyssen wrote:
> On Mon, Sep 08, 2003 at 11:36:33AM +0200, Jim Segrave wrote
>
> Kees' experiments show that cube decisions errors don't weigh as much as
> chequer play errors. I can't offer any explanation for this, other than
> gnubg's chequerplay is much better than the cube play???

>From a comment in the thread on GammOnLine:

================

seems to me that checker play errors in real matches represent are
always an irretrievable loss of equity, while cube errors may or may
not matter, depending on the flow of the game (5 missed marginal
doubles with an eventual correct double/take), and opponent's error
(too good to double, but he took.) Objective cube errors may not even
be errors (there's little play-the-opponent in checker play, but a lot
in cube action). Further, it seems that cube errors against weaker
opponents are relatively less costly than cube errors against stronger
opponents (against a weakie I can recover from a bad take and gammon
loss in the first game of a 5-point match, or choose to play the whole
match semi-cubeless, or take "passes" that opponent's checker errors
make takes -- in gnu's eyes I'll be a "casual cubist" in all cases).

================

Which also leads to the observation that you can only make a given
chequer play error once in a game, you can accumulate say .050 or so
per missed double for several moves (try failing to double when your
opponent is post Crawford to see how big a cube error you can
generate).

If the rating calculation is done by the average cube error, then the
fact that the average is calculated by only considering actual or
close decisions, which can keep the cube average error higher.

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