[rhm]

 gnasher, on 2012-July-06, 03:21, said:

Why should I show you anything? You've asserted that, for the particular category of deals we're discussing, double-dummy analysis acurately models single-dummy play. So far as I can see, you have provided neither evidence nor argument in support of this assertion. And now you want me to do the work of testing it?

Nobody ever claimed double-dummy analysis accurately models single-dummy play. In fact it does not. Bridge is not played double dummy and never will be. (Thanks heaven)
What has been shown is that the differences cancel out and the outcome measured between average number of tricks taken at the table and by double dummy is over a large sample very close.

This has been shown for actual table contract results with only slight variations depending on strain and level.
Single dummy declarers have a slight, but only a slight, advantage in low level contracts, in particular notrump, supporting the view that 1NT is hard to defend.
(An argument for not running away from 1NT)
Single dummy declarer are at a slight disadvantage at slam contracts, where the defense often has few options and can therefor defend often double dummy.
This is not the case for declarer, who must uncover and then choose between options.
These differences are easy to understand.

So far I have heard no convincing arguments why 4-3 fits might possibly be any different and if it were, why does it not show up markedly already when the analysis of the total sample (30 million plays) was broken down according to strain and level?
After all 4-3 fits are much more common at low-level major suit contracts than anywhere else.
If a single dummy declarer is really at a disadvantage when playing 4-3 fits, why does this not show up?
Maybe 4-3 fits are harder to play, maybe not. But if they are, I do not see that the defense against 4-3 fits is on average any easier.
After all the defense may not even know that declarer is in a 4-3 fit.

I consider this pretty good evidence for my view.

Rainer Herrmann

[gnasher]

 rhm, on 2012-July-06, 05:44, said:

So far I have heard no convincing arguments why 4-3 fits might possibly be any different and if it were, why does it not show up markedly already when the analysis of the total sample (30 million plays) was broken down according to strain and level?
After all 4-3 fits are much more common at low-level major suit contracts than anywhere else.
If a single dummy declarer is really at a disadvantage when playing 4-3 fits, why does this not show up?
Maybe 4-3 fits are harder to play, maybe not. But if they are, I do not see that the defense against 4-3 fits is on average any easier.
After all the defense may not even know that declarer is in a 4-3 fit.

Perhaps because declarer's disadvantage in 4-3 fit partscores is counterbalanced by declarer's advantage in some other category of partscore. Or perhaps you're right and there is no significant declarer's disadvantage in 4-3 fits. I don't know - I'm not arguing that you're wrong, just that we should be properly sceptical. It seems unduly credulous to assume that an average which applies to all hands also applies to any given subset of hands, especially if this assumption leads to a conclusion which most people would find surprising.

[aguahombre]

So, is there a chance Cherdano's bet from post #45 can be set up to mutual satisfaction? Or are the conditions too tough to agree upon?

[benlessard]

DD isnt super reliable but I think its more reliable than human judgement in most of the cases. I think what is important is really understanding where DD fail and the degre of correction we need to apply. It will be nice to have a complete and user friendly simulator.

1-In low level contract DD greatly favor defense for the leads.
2- Hand where trumps dont break DD favor declarer.
3- 2 way finesse

etc

Once these things are better understood DD will be a great tool IMO