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Re: [Bug-gnubg] Effective pip count (EPC) bug
From: |
Christopher D. Yep |
Subject: |
Re: [Bug-gnubg] Effective pip count (EPC) bug |
Date: |
Fri, 05 Sep 2003 06:51:48 -0400 |
At 12:47 AM 9/5/2003 -0400, I wrote:
Windows XP, GUI version
version 0.14-dev 1.1345 030904
version 0.14-dev3D 1.1345 030904 [bug exists in both old and "3D" versions
of gnubg]
Set-up the following position:
GNU Backgammon Position ID: /wAAAP4BAAAAAA
Match ID : cAkAAAAAAAAA
+24-23-22-21-20-19------18-17-16-15-14-13-+ O: gnubg
OO | O | | | 0 points
OO | O | | |
O | O | | |
O | O | | |
O | 8 | | |
| |BAR| |v (Cube: 1)
X | 8 | | |
X | X | | |
X | X | | |
XX | X | | | On roll
XX | X | | | 0 points
+-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: Chris
Then,
show onechequer
gnubg reports that each side has an EPC of 12.578 (and an avg. rolls (to
bearoff) of 12.578/8.167 = 1.540). This is incorrect; the correct EPC is
about 29.
Sorry, for some reason I mixed up "show onesidedrollout" with "show
onechequer". So, gnubg is correctly reporting that the EPC for a single
checker on the 8 point is 12.578. No bug here.
Also, the onechequer statistics reverses the players. The pips, Avg.
rolls, Std. dev., EPC, and wastage numbers listed for player "gnubg" are
actually those of player "Chris" and vice-versa (the above is a symmetric
position, but change gnubg's position to 7 on the 1 pt. and 1 on the 2 pt.
for example).
This is an actual bug in "show onechequer" however.
Also, "show onesidedrollout" reverses the Effective pip count numbers when
player0 is on roll (if player1 is on roll the numbers are correct). For
example:
GNU Backgammon Position ID: /wAAAP4CAAAAAA
Match ID : MAEAAAAAAAAA
+-1--2--3--4--5--6-------7--8--9-10-11-12-+ O: gnubg
OO | O O | | | 0 points
OO | O | | | On roll
O | O | | |
O | O | | |
O | 7 | | |
| |BAR| |^ (Cube: 1)
X | 8 | | |
X | X | | |
X | X | | |
XX | X | | |
XX | X | | | 0 points
+24-23-22-21-20-19------18-17-16-15-14-13-+ X: Chris
"show onesidedrollout" reports:
EPC Wastage
Player gnubg 28.999 20.999
Player Chris 29.005 20.005
The correct numbers are (29.005, 20.005) and (28.999, 20.999) for gnubg and
Chris respectively.
Chris