symmetric bearoff positions

Harald Retter

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Dec 10, 1998, 3:00:00 AM12/10/98

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Walter Trice wrote:

Here's a trivia question for you bear-off buffs:
What is the symmetric bearoff with the smallest pip count that
is not an initial double?
I'll try to remember to post the answer some time if nobody
gets it :-)

Walter Trice

Walter, I am still curious :-o

Harald Retter

stein....@fou.telenor.no

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Dec 11, 1998, 3:00:00 AM12/11/98

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In article <366fe...@news.aranea.net>,

"Harald Retter" <Harald.Re...@rhein-main.netsurf.de> wrote:
> Walter Trice wrote:
>
> Here's a trivia question for you bear-off buffs:
> What is the symmetric bearoff with the smallest pip count that
> is not an initial double?
> I'll try to remember to post the answer some time if nobody
> gets it :-)

My guess is [ 1 7 0 0 0 0 ] for 15 pips
--
Stein K

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Walter Trice

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Dec 12, 1998, 3:00:00 AM12/12/98

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stein....@fou.telenor.no wrote in message
<74qog3$62p$1...@nnrp1.dejanews.com>...

>In article <366fe...@news.aranea.net>,
> "Harald Retter" <Harald.Re...@rhein-main.netsurf.de> wrote:
>> Walter Trice wrote:
>>
>> Here's a trivia question for you bear-off buffs:
>> What is the symmetric bearoff with the smallest pip count that
>> is not an initial double?
>> I'll try to remember to post the answer some time if nobody
>> gets it :-)
>
>My guess is [ 1 7 0 0 0 0 ] for 15 pips
>--
>Stein K
>

Nice "guess"! That's the one.

-- Walter Trice

highlander

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Dec 14, 1998, 3:00:00 AM12/14/98

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>>My guess is [ 1 7 0 0 0 0 ] for 15 pips
>>--
>>Stein K
>>
>Nice "guess"! That's the one.
>
>-- Walter Trice

now my question - why ?
i thought doubling is ok in bear off positions if the pip is lower or equal

thanks for reading

alain aka highlander

Walter Trice

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Dec 15, 1998, 3:00:00 AM12/15/98

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highlander wrote in message <752lib$1mt$1...@sibyl.sunrise.ch>...

Unfortunately, the real answer to the question of "why", for any particular
position, is to do a lengthy and very tedious computation and find out what
is right.

In general terms, the reason that you might not double in a position where
you are the favorite, is that access to the cube has value, and when you
double you deprive yourself of cube access.

Let's say that for a fixed stake and cube level, your equity when the cube
is centered is X, and your equity when your opponent owns the cube is Y.
Then [when the Jacoby rule isn't a factor] it is always true that X >= Y,
and usually true that X > Y. Sometimes X < 2*Y, and then it's right to
double. Sometimes X > 2*Y, and then it isn't.

The alleged rule that you can double in bear-off positions with an equal or
lower pip count is simply not true in general.

A better rule is this: if the position is symmetrical, double if your pip
count is less than 30; otherwise don't double. There are exceptions at both
ends of the spectrum, such as the one Stein K mentions above.

This rule is based on a complete scan of the Sconyers database for positions
with 9 and fewer checkers.

-- Walter Trice

highlander

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Dec 15, 1998, 3:00:00 AM12/15/98

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thanks

highlander