Author: Robert Hyatt
Date: 19:12:00 10/27/99
Go up one level in this thread
On October 27, 1999 at 16:27:58, Peter Kappler wrote: >On October 27, 1999 at 13:50:46, Dann Corbit wrote: > >>On October 27, 1999 at 11:47:14, Robert Hyatt wrote: >>[snip] >>>If you play someone that far under you, you had better win every game, or else >>>your rating _only_ can go down. >> >>But if they are really that far under you, you will win the expected number on >>average, and your number will stay the same. >>Consider the following table: >>Win expectency for a difference of 0 points is 0.5 >>Win expectency for a difference of 100 points is 0.359935 >>Win expectency for a difference of 200 points is 0.240253 >>Win expectency for a difference of 300 points is 0.15098 >>Win expectency for a difference of 400 points is 0.0909091 >>Win expectency for a difference of 500 points is 0.0532402 >>Win expectency for a difference of 600 points is 0.0306534 >>Win expectency for a difference of 700 points is 0.0174721 >>Win expectency for a difference of 800 points is 0.00990099 >>[snip] >>Win expectency for a difference of 2000 points is 9.9999e-006 >> >>If you play someone one hundred points lower than you, they will get 36% of the >>points and you will get 64% and your rating will stay the same. >>If you play someone 200 points lower, you will get 76% of the points and they >>will get 24% and your rating will stay the same. If you play someone 300 points >>lower, you will get 85% of the points. If you play someone 400 points lower you >>will get 91% of the points. At a 500 point difference, you will win 95% of the >>points. At a 600 point difference, you will get 97% of the points. At a 2000 >>point difference, you will win 99.99% of the points. In all cases, your rating >>will stay the same. Playing lower rated players should not (in theory) change >>your rating at all. The very rare draw or extremely rare loss to a low-rated >>player will be balanced out by a bazillion wins. On the other hand, games >>against players hundreds of points beneath you are not really very exciting >>[imo]. Who would gather around to watch Kasparov play me? If he played Anand >>or Adams or some highly skilled player, that would be something people want to >>watch. The reason is that I have basically no chance of winning so the outcome >>is pretty well known even before we start. So from a point of interest, I don't >>think it makes a lot of sense to play opponents that are miles beneath. >> >>Those that claim your rating can be inflated by choosing opponents are not aware >>of how the math works. > > >Just the opposite. We understand the math very well. See below. > > > And (let's suppose) that you have played someone ten >>times and lost them all. You might think that -noplay would be good for you. >>But look at all the recent SSDF contests where one program had a big lead and >>suddenly lost it. Without a huge number of games, there is really no way to >>know what the win expectancy would be, and once we know it accurately, then it >>will only reflect upon our true rating. >>[snip] > > >But you don't need to be 100% certain to make a good decision. Consider this >scenario: > >I play 10 games against Player X at a 3 0 time control, and get smashed, 9-1. >Then I play 10 more games at a slower time control like 5 3, and break even. If >I want to save rating points in the future, I will simply decline any 3 0 >challenges from this guy. Even though I made my decision based on a relatively >small sample size, it's probably the correct decision. Playing another 100 >games against "just to be sure" is sub-optimal if the goal is to maintain a high >rating. > >If you spend enough time on ICC, you'll see this stuff happen *all* the time. > >--Peter Absolutely true. A couple of automatic computers discovered that my parallel search + null move search is not great (vs a computer) in 1 0 or 2 0 games. I could beat them regularly at 5 0 or 5 3. So they only played 1 0 and 2 0. Others discovered my default contempt setting and found ways to exploit it until I fixed that as well. So you are definitely correct. Players notice what is going on and take advantage of it when they can. Good incentive to fix those problems...
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