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## Re: current development

 From: Joseph Heled Subject: Re: current development Date: Sun, 8 Dec 2019 10:23:34 +1300

On Sun, 8 Dec 2019 at 10:15, Timothy Y. Chow <address@hidden> wrote:
On Sun, 8 Dec 2019, Joseph Heled wrote:
> Of course you need to weight every position with the probability it
> occurs in actual play.

You say "of course," but I don't agree.  Weighting things in that way
amounts to demanding perfection only from the starting position.  In my
book, perfection means perfection from any legal position.  This is
sometimes referred to as "strongly solving" a game as opposed to "weakly
solving" or simply "solving" it.

Agreed, but from a practical point of view, not caring about non-reachable positions and positions with a very low probability is good enough for a playing-bot.

And again, from a practical point of view, not redoubling past (say) 64 is a reasonable tactic for a playing-bot (unless in a race).

(said by someone who is 1500 player in money games. also, the requirements from a "playing-bot" might be very different than the ones from an "analyzing bot")

-Joseph

> I don't think 2009 threads are a good indication. We need something with
> the current net, which I think is better.

This is fair.  I would guess that GNU 2-ply (version 1.xx) and XG 3-ply
(version 2.xx) are still susceptible to the tactic, though less so than
earlier versions.  But this is just speculation; the only way to find out
is for someone experienced with the relevant tactics to try it out.

I think that XG won't let you turn the cube past 1024 in actual play, so
that might be an obstacle.  What typically happens in a money session is
that the human loses a long string of games and then makes up for it in a
favorable game, when the bot will beaver and redouble when it is losing.
If you can get the bot to do this a few times in a row then you can win
thousands of points in a single game.  If your goal is simply to come out
ahead at the end of the session, then you might need to win just one such
super-favorable game, since then you can protect your lead by dropping all
doubles in all subsequent games, and refusing to double yourself until
you're sure it's a drop.

Of course any computer is going to have *some* limit on the cube but I
doubt that a cap of 2^30 or even 2^20 will be a serious limitation.

Tim