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## [Bug-gnubg] Re: 0-ply cube

 From: Joseph Heled Subject: [Bug-gnubg] Re: 0-ply cube Date: Sun, 08 Jun 2003 08:53:21 +1200 User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2) Gecko/20021202

```I don't have a gammonline account. Can I see some of the positions please?

-Joseph

Albert Silver wrote:
```
```Hi,
```
I'm sending this via direct e-mail as opposed to the GNU mailing list
```because the post is in HTML and I'm not sure whether the mailing list
would preserve this in a readable format. Michael Depreli posted the
following in GoL regarding some very strange GNU behaviour in 0-ply cube
decisions which I am sending to you.
```
Albert
```Examples Of GNU 0-ply cube oddness.

```
Date: Saturday, 7 June 2003, at 3:07 a.m. Here's some evidence that GNU 0 ply cube is unreliable for Double/No
```Double decisions.
These were the first three double/no double decisions from one of the
money sessions between SW and GNU and nearly all the others I looked at
suffer from the same peculiarities. I haven't shown the positions
because they are not relevant.
Notice the No/Double & Double/Take equities are always identical and in
fact GNU never doubles
regardless of whether it's an optional double or not. S4's 1ply (GNU 0
ply Equiv) is shown in red.

```
```Cube decision

0-ply cubeless equity
+0.509
```
0.635 0.297 0.014 - 0.365 0.070 0.001
```
Cubeful equities:

1.
No double
+0.770
```
```2.
Double, pass
+1.000
+0.230

3.
Double, take
+0.770
+0.000

Proper cube action:
Optional double, take
```
SW4: 0.687/0.774
```Cube decision

2-ply cubeless equity
+0.514
```
0.634 0.304 0.019 - 0.366 0.075 0.002
```
Cubeful equities:

1.
Double, take
+0.780
```
```2.
Double, pass
+1.000
+0.220

3.
No double
+0.634
-0.146

Proper cube action:
Double, take
SW4: 0.683/0.784

Cube decision

0-ply cubeless equity
+0.535
```
0.669 0.266 0.009 - 0.331 0.076 0.001
```
Cubeful equities:

1.
No double
+0.846
```
```2.
Double, pass
+1.000
+0.154

3.
Double, take
+0.846
+0.000

Proper cube action:
Optional double, take
SW4: 0.738/0.853

Cube decision

2-ply cubeless equity
+0.548
```
0.674 0.263 0.010 - 0.326 0.071 0.001
```
Cubeful equities:

1.
Double, take
+0.874
```
```2.
Double, pass
+1.000
+0.126

3.
No double
+0.794
-0.080

Proper cube action:
Double, take
SW4: 0.792/0.882

Cube decision

0-ply cubeless equity
+0.599
```
0.654 0.340 0.026 - 0.346 0.074 0.002
```
Cubeful equities:

1.
No double
+0.962
```
```2.
Double, pass
+1.000
+0.038

3.
Double, take
+0.962
-0.000

Proper cube action:
No double, take (0.0%)
SW4: 0.667/0.741

Cube decision

2-ply cubeless equity
+0.550
```
0.636 0.338 0.027 - 0.364 0.083 0.003
```
Cubeful equities:

1.
Double, take
+0.853
```
```2.
Double, pass
+1.000
+0.147

3.
No double
+0.761
-0.093

Proper cube action:
Double, take
SW4: 0.692/0.721
```
```Re: Examples Of GNU 0-ply cube oddness.

```
Date: Saturday, 7 June 2003, at 3:32 a.m. In Response To: Examples
```<http://www.gammonline.com/members/board/config.cgi?read=54891> Of GNU
```
0-ply cube oddness. (Michael Depreli) Michael, I am not sure how much trust one can put into the cube evaluations at
```low plies. Often S4 doubles at its 2-ply level but reverses the decision
at the 3-ply level by a significant margin. The 1-ply level is probably
```
even less reliable. Also note how different the equities reported by Snowie and GNUBG are. I
```still wonder why the two bots produces equity differences of such
```
magnitude. Ilia
```Re: Examples Of GNU 0-ply cube oddness.

```
Date: Saturday, 7 June 2003, at 6:15 a.m. In Response To: Re: Examples
```<http://www.gammonline.com/members/board/config.cgi?read=54892> Of GNU
```
0-ply cube oddness. (Ilia Guzei) I'm already on record as stating I would never use GNU 0-ply or SW 1-ply for evaluating cube decisions. I posted these example because I still see rollouts posted here using 0-ply cube which I really don't trust. To be honest I don't actually know the overall effect it has on rollouts
```but it can't be good when these positions show GNU 0-ply refuses to
```
double! Sure S4 changes it's decision from 2 to 3 ply because it's another ply of accuracy with sound mathematical doubling formulae behind it. My guess is S4 1-ply uses a simplistic cubeless to cubeful conversion
```and bases it's decision around some borderline level, which although not
good enough for serious stundents IMHO at least looks more sensible than
```
GNU's attempt. I guess if you analaysed a huge number of cube decisions you could come
```up with a cubeless equity which would average out being borderline for
double/no double decsion. Maybe even some of Janowski's formula could
```
improve on this method. Michael
```

```