Cube 119 - Ahead 2-0 3-away

[sixty_something]

If the board image does not appear in the question above, you may view it in the attached PNG file below.

one vote per user .. results of the poll are shown after you have voted

Sometimes the cube can be a most intimidating weapon, but it is a double edged sword. In this situation, RED's cube, if declined, gives RED an imposing 3-0 lead. If accepted, WHITE with chances of escaping and maintaining the lead in pip count can tie the match with a win or with a gammon or a redouble have a chance to take the lead into the Crawford game. GNUbg says the correct actions are

Spoiler

In this match, the finals in adz's "cheap and nastyl" - 3/5 tourney, with some hesitation I accepted johwayne's agressive cube, escaped and tied the match with a declined redouble a few moves later. Frankly, I thought it was a good cube and considered passing. GNUbg said it was an awful cube making my considering to pass equally awful.

Cube analysis

4-ply cubeless equity  +0.131 (Money:  +0.098)
  0.518 0.138 0.002 - 0.482 0.077 0.002

Cubeful equities:
1. No double            +0.060
2. Double, pass         +1.000  ( +0.940)
3. Double, take         -0.557  ( -0.617)

Proper cube action: No double, take (39.6%)

0-ply cubeless equity  +0.128 (Money:  +0.091)
  0.518 0.144 0.003 - 0.482 0.088 0.002

Cubeful equities:
1. No double            +0.043
2. Double, pass         +1.000  ( +0.957)
3. Double, take         -0.501  ( -0.544)

Proper cube action: No double, take (36.2%)

[close]

you may enter the ID's below into GNUbg or Snowie to evaluate your answer:

Position ID: OM/BAyDGTuGAAw Match ID: MAGgACAAAAAA


There comes a time when a man must spit on his hands, hoist the black flag and begin slitting throats.
-- H. L. Mencken US editor (1880 - 1956)               

[spielberg]

What's a "staggler"? (I had to ask before dorbel does). johwayne is far from the only fibster I know whom's extremely aggressive with the cube - I suspect surfing alters one's perception of risk.

[sixty_something]

a "staggler" is what you get when spell check doesn't work in the poll question  thanks for the correction

[adrian]

Spoiler

The first option in poll should have been no double, take instead of no double. Like gnu says: Proper cube action: No double, take (39.6%)

[close]

Ok , I am picky , i know.

[sixty_something]

adrian, the context in which i ask the question of "What are the proper cube decisions?" is slightly and subtlely different from the way GNUbg presents its cube analysis. So, a decision of "No cube" stands alone as an independent choice as there is no response when no cube is offered. If and only if a cube is offered, do the take/pass responses make sense. Too good to cube is another category still. IMO, these four choices for answers fit almost all cube problems in which I ask the question as above. A differently worded question might use the style you suggest

[PersianLord]

IMO, these four choices for answers fit almost all cube problems in which I ask the question as above. A differently worded question might use the style you suggest

Sometimes it's Too good to double/Take. I saw the related position in a BG board a few months ago, if my memory serves me right.

[sixty_something]

recently, one of my cube problems (117 or 118) drew a comment from spielberg which caused me to go back and add a Too good to double/Take answer .. i thought about that afterwards .. in hindsight, i didn't like that answer, but in the context of that problem and spielberg's comment i left it in

in general, i don't ever recall GNUbg suggesting a Too good to double/Take in its evaluations .. for me, in the context  or GNUbg evaluations, it doesn't even make sense as a possibility .. while it certainly may be the case where a given match score when a cube is offered, even when too good to double, a take and redouble might be in order or optional .. however, in that case it is not likely a cube thrown from what GNUbg describes as a too good to double situation .. so, for the context of my cube problems and the manner in which i ask for "proper cube decisions" such a case would more likely simply fall into the category Double/Take .. i use Too good to double/Pass on almost all cube problems .. adding Too good to double/Take to all such problems may be worth considering, but at present i can see doing that on a case-by-case basis at best

[playBunny]

I'm not entirely certain but I think it's something like this: Too good to double/Take means that the gammon chances are good for the cube holder, as usual, however the double not only wastes that potential but is also a gift to the trailer because they are so weak in position and match score that they are pretty dead. The cube is a boon and they should take and redouble with gratitude - and a prayer to the Dice Gods for the hit that they need.

[dorbel]

Too good to double/take is a nonsense. See my reply to Spielberg at the end of the thread to pos 118. In matches there are only four possible cube actions. They are no double/take, double/take, double/pass and too good to double/pass.
A position that is too good to double means that the player on roll has an equity of greater than 1 point if he plays on, so clearly if he incorrectly offers the cube then the player being doubled passes to limit his loss to 1 point.

[playBunny]

Stranger things have happened. In a hypergammon match I got, and I swear this is true, Proper cube action: Eat it!

But, regarding the Too Good to Double/Take, you might want to consider the following

http://groups.google.co.uk/group/rec.games.backgammon/browse_frm/thread/50c19d48e279049?hl=en&ie=UTF-8&q=%22Too+good+to+double/Take+%22

[sixty_something]

  very interesting, bunny .. thanks for that link .. i didn't know GNUbg ever used Too good to double, take, but that appears legit .. i don't have time to look at it right now, but will later .. on first glance it appears such a situation is dependent on the match score as we have suggested .. in that one, the cube is thrown by the side ahead 8-0 in an 11 point match .. i wonder if the correct next play is a redouble .. in that situation, facing a 0-10 Crawford game or even loss by gammon, i'd redouble immediately

[dorbel]

I think that that post has to be a Gnu glitch.

[playBunny]

I think that that post has to be a Gnu glitch.

You might be right.

In match play, there are many positions in which you are too good to
double, but where your opponent can take if doubled. Of course, this
shouldn't be the case in money play... but is there a simple proof? Can
anyone cite a reference?

It comes out as a consequence of something that will be in my December
25th column in GammonVillage.com , but my proof is a bit convoluted.


Douglas Zare

And you might be wrong.

http://groups.google.co.uk/group/rec.games.backgammon/browse_frm/thread/42e272fe26001a85/7e23231a4eacc222?hl=en&lnk=gst&q=%22Too+good%20to+double%22+Take+#7e23231a4eacc222

[dorbel]

If you understand zare's proof, expain it to me!

[playBunny]

If you understand zare's proof, expain it to me!

Zare's proof doesn't pertain to what we're talking about. I quoted his entire first post as an appetiser. Methinks you didn't bother reading the thread, which is what you were being invited to do.

So there's GnuBg, Racoon and Douglas Zare all spouting "nonsense" and there's you declaring it to be this nonsense, yet you haven't read the threads. (Or if you have, your challenge indicates that you didn't understand it.)

Which doesn't further the discussion so I'll leave it at simply: "Experts' opinions are divided".

[dorbel]

Actually I did read the thread. Zare's proof in his Dec 25th column will if I read him correctly pertain to this. Doug Zare's writing is fairly impenetrable to me at the best of times, so if he says that his proof will be "a bit convoluted", watch out. As I say, let me know if you understand it.
Perhaps in the end, as Hugh McNeill points out, it is all a matter of semantics. The important thing is to arrive at descriptions that enable us all to understand the position. For me, the theoretical possibility of "too good/take" isn't helpful, perhaps for DZ, who has a brain the size of a planet, it is helpful.
Note that all these descriptions are theoretical and assume correct cube actions by the opponent. Of course if you factor in the possibility of incorrect takes or passes, now and later, all sorts of cube actions become possibly correct.

[playBunny]

Actually I did read the thread. Zare's proof in his Dec 25th column will if I read him correctly pertain to this. Doug Zare's writing is fairly impenetrable to me at the best of times, so if he says that his proof will be "a bit convoluted", watch out. As I say, let me know if you understand it.

As I said, his proof is irrelevant. It's a proof that ND>DP>DT (Too Good/Take) and ND>DT>DP (Double/Pass) cannot occur in money games.

[dorbel]

lol, as I said, I can hardly ever understand what doug is on about! So where is the proof that Too good to double/take is a theoretical possibility in matches? Can we see a position that fulfils those requirements? The position we were shown in 2006 by fretmeister certainly isn't one.

[playBunny]

Lol. No, my last post was only to correct your misunderstanding of the man whose output you cannot fathom. I'm quite happy to leave it as before: Experts' opinions are divided.

[Zorba]

"Too good to double, take" is definitely an option in match play and not extremely rare or theoretical. Raccoon explained it very well.

Too good to double means your equity BEFORE doubling is over 1. It does NOT mean your equity AFTER a double/take is over 1. That's the catch.

It happens most often in situations where the player is LEADING at a 2-away score (versus 3-away or 4-away) in a highly gammonish position. Why? Because when the leader doesn't cube, gammons will win him the match, but when he does cube, his gammons have no value anymore and the trailer can rewhip to put the entire match on the line.

So if the LEADER has a position where he could win a lot of gammons, but at the same time he's not that big a favorite to win, the leader should play on for the gammon (he wins relatively many), but if the leader doubles anyhow, the trailer should TAKE, because now gammons have no value anymore, and the trailer can put the match on the line with his still considerable SINGLE wins.

In numbers, something like:
60% total wins, 40% gammon wins, 40% losses (i.e. a gammon rate of 67%, 2/3 of wins will be gammons)
will qualify for "too good, take" at a 2-away 4-away score

[sixty_something]

an excellent reply, Zorba .. while i haven't had the time to read and attempt to "penetrate" Doug Zare's comments, what you have summarized as a Too good to cube/Take situation makes really good sense, to me

this thread within a thread has been most interesting .. the problem itself, was solved by most answering the initial poll and appears to almost be a trivial one in comparison to the issues raised by these responses

when i have the chance, i will split off these replies and retitle the new thread as Too good to cube/Take .. it is just possible this will come up again and perhaps even be found in analysis in few more positions .. for now, continue to reply here, if desired, on this Too good to cube/Take issue .. it will likely be a few days before i can get around to moving it to a new thread

[dorbel]

Thank you Zorba, a much clearer explanation than raccoon's. However, this sort of position is normally described by humans and bots as being no double/take, even though the equity in emg is over 1 before doubling. It is just a question of semantics. The position as originally posted though, has gnu clearly saying "Too good to double/take". Gnu on my machine says "no double/take" for the identical position and settings. Any clues on that?
IMO the traditional description is better.

[Zorba]

There are indeed many players and some bots that will label "too good to double, take" as "no double, take" or worse, "not good enough, take". Maybe a matter of taste or habit, but I think it might also just be an oversight or lack of understanding sometimes.

Of course, the correct cube action for both players is the same: do not double; and after a wrong double, a take for the opponent.

However, there is still an important difference between "too good, take" and "no double, take", and that is, what happens when opponent makes a mistake and passes? The chance of an opponent making a mistake after you double is often some extra equity you get from doubling, and can make a theoretically wrong double correct in practice.

If you get an incorrect pass when it's actually "no double (not good enough), take", you are probably gaining a huge chunk of equity. A typical GNUBG output might read:


+0.600 No Double
+0.550 Double, Take
+1.000 Double, Pass

Correct cube action: No Double, Take (12.5%)


That figure in brackets, 12.5% tells you when it becomes profitable in practice, to double anyhow: If the chance of opponent incorrectly passing is 12.5% or more, doubling is correct! The reason is that you gain 1.000-0.600=0.400 on an incorrrect pass, and the loss comes at only 0.550-0.600= -0.050.



Now, by contrast, if you get an incorrect pass when it's actually "too good to double, take", you are still losing equity! After all, a pass gains you exactly 1 point, but you were too good, so playing on would have gained you more than 1 point.

So, it is NEVER correct to double a "too good, take", not even if your opponent would somehow blunder with a pass.

Here's an example of "too good, take", X launched a rather succesful blitz, two of O's checkers are on the bar, the 6-5-4 points are made, but the position is still far from "gin" for X:

    GNU Backgammon  Position ID: 4NvgAWBqd4gBJA
                    Match ID   : cAmlABAAGAAA
    +24-23-22-21-20-19------18-17-16-15-14-13-+  O: samirah
    | X     X        O | O | O  O           X |  1 point
    |                O | O | O  O           X | 
    |                O |   |                  | 
    |                O |   |                  | 
    |                O |   |                  | 
    |                  |BAR|                  |v 5 point match (Cube: 1)
    |                  |   |                  | 
    |                  |   |                O | 
    |             X  X |   |                O | 
    |          X  X  X |   |                O |  Rolled 21
    |    X  X  X  X  X |   |          X     O |  3 points
    +-1--2--3--4--5--6-------7--8--9-10-11-12-+  X: You

X on roll (clockwise), cube action?

Cube analysis
2-ply cubeless equity  +1,475 (Money:  +1,107)
   78,5%  56,7%   1,6% -  21,5%   4,4%   0,2%
Cubeful equities:
1. No double            +1,089
2. Double, pass         +1,000  ( -0,089)
3. Double, take         +0,698  ( -0,391)
Proper cube action: Too good to double, take


If you incorrectly double here, and opponent passes, then your opponent is making a huge blunder: he loses 0.302 equity compared to a correct take.

However, even after that huge blunder, the doubler still loses 0.089 equity over simply playing on.

It's just that the doubler would have lost much more, namely 0.391 equity, if opponent had correctly taken his blunderish cube. But it's still a loss.


(N.B.: My original example with numbers wasn't good, more realistic is something like:
80% total wins, 60% gammons (i.e. a 75% gammon rate), 20% losses
to cause a "too good, take" at 2-away, 4-away)

(N.B. 2: the position in the rec.games.backgammon thread also comes out as a "no double, take" on my GNUbg, probably has to do with different match equity tables being used)

[playBunny]

However, this sort of position is normally described by humans and bots as being no double/take, even though the equity in emg is over 1 before doubling. It is just a question of semantics.

Humans, maybe, but GnuBg wouldn't know what semantics were if you spent 10 years trying to tell it. It does know about comparing numbers and making branches in program flow. To a bot it's a mathematical decision, not a semantic one. The fact that one GnuBg evaluation says Too good to double/take and the other says No double/take demonstrates that.

The position as originally posted though, has gnu clearly saying "Too good to double/take". Gnu on my machine says "no double/take" for the identical position and settings. Any clues on that?

The settings are not identical. You're using the g11 MET. Try the position with Woolsey's.