cube considerations under Jacoby rule

[KLG]

I have played some money games with and without the Jacoby rule, and I
was wondering how the rule affects cube decisions.

It seems right to me that there will be more Double/Drops with the JR
than without the JR. (Since there will be no NoDouble/Drops with the
cube at 1.)

But what about early doubles? Does the JR motivate more early
doubling...or am I missing the point?

Thanks,
KLG

[Douglas Zare]

KLG wrote:

> I have played some money games with and without the Jacoby rule, and I
> was wondering how the rule affects cube decisions.
>
> It seems right to me that there will be more Double/Drops with the JR
> than without the JR. (Since there will be no NoDouble/Drops with the
> cube at 1.)

Yes, that is correct. You don't need to worry about being too good to
double with the Jacoby Rule, only too good to redouble.

> But what about early doubles? Does the JR motivate more early
> doubling...or am I missing the point?

There are a few situations in which there are correct doubles with the
Jacoby Rule that are not correct without the Jacoby Rule. Usually it does
not make much of a difference. Exchanges which leave you too good to
double are larger market losers with the Jacoby Rule, since you regret not
doubling more. However, most of the time, the value from being too good to
double is small compared to the difference between taking and passing the
position.

The Kauder paradox is that with the Jacoby Rule, there are some positions
where it is correct to double even though your double will be beavered.
Generally, these would be positions with overwhelming gammon and
backgammon chances if you hit a direct shot, but in which you will be
doubled out if you miss. Latto's paradox is that there are positions which
are redoubles that are not initial doubles. This may happen if your
opponent is an underdog, but wins many more gammons than you do, so that
your opponent may end up too good to double without the Jacoby Rule.

Douglas Zare