## what is the current slope of the curve

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CRoberson
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### what is the current slope of the curve

History has shown that one gets 200 elo for each ply (all else the same)
and an initial rating below 2200. This is a linear progression and many
claimed that it wouldn't continue. It was thought that the slope would
change toward diminishing returns.

Does anybody have data or know of a reference that states what the
curve looks like with a rating above 2200?

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### Re: what is the current slope of the curve

CRoberson wrote:History has shown that one gets 200 elo for each ply (all else the same)
and an initial rating below 2200. This is a linear progression and many
claimed that it wouldn't continue. It was thought that the slope would
change toward diminishing returns.

Does anybody have data or know of a reference that states what the
curve looks like with a rating above 2200?
I guess this depends on how much pruning an engine is doing. If there's more pruning done, the rate of change of ELO with respect to depth will become less.

hgm
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### Re: what is the current slope of the curve

But in such engines the slope would also be less if you set them to a search depth that would make them play below 2200 ELO. And there is no engine yet that has 2200 ELO at 1 ply, so one can lbring all existing engines in the region.

I think the question is how for one and the same engine the ELO per ply behaves as a function of total depth at maximum depth vs low depth.

CRoberson
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### Re: what is the current slope of the curve

Reviewing the CCRL date, I see that each doubling of processors is
worth 50 rating points if the single proc version is rated >= 2800.

Lots of good data there. The web pages are very well organized.

bob
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### Re: what is the current slope of the curve

hgm wrote:But in such engines the slope would also be less if you set them to a search depth that would make them play below 2200 ELO. And there is no engine yet that has 2200 ELO at 1 ply, so one can lbring all existing engines in the region.

I think the question is how for one and the same engine the ELO per ply behaves as a function of total depth at maximum depth vs low depth.
All someone needs to do is set this up on ICC and let it run for a few months. Start at depth=1 for 2 weeks and see where the rating stabilizes, then sd=2, 3, ...,

mjlef
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### Re: what is the current slope of the curve

The "sahpe of the curve" is a lot harder to judge now. Programs using Late Move Reductions, Null Move Reductions and other pruning typically have a branching factor of about 2 versus something like 6 for a traditional program. Of course these reductions mean the length of the tree varies a lot, and so they miss things. Programs are much more selective now. Testing results suggest an extra ply is worth around 50 ELO. A more accurate curve would not use depth at all, but some sort of time units. How much is each doubleing of time worth, for example.