Author: Ricardo Gibert
Date: 16:22:43 01/04/04
Go up one level in this thread
On January 04, 2004 at 14:57:59, Mike Byrne wrote: >On January 04, 2004 at 13:46:48, Ricardo Gibert wrote: > >>On January 04, 2004 at 12:47:25, Peter Berger wrote: >> >>>On January 04, 2004 at 12:40:00, Ricardo Gibert wrote: >>> >>>>On January 04, 2004 at 12:29:15, Mark Young wrote: >>>> >>>>>On January 04, 2004 at 11:46:00, Roger Brown wrote: >>>>> >>>>>>Hello all, >>>>>> >>>>>>I have read numerous posts about the validity - or lack thereof actually - of >>>>>>short matches between and among chess engines. The arguments of those who say >>>>>>that such matches are meaningless (Kurt Utzinger, Christopher Theron, Robert >>>>>>Hyatt et al)typically indicate that well over 200 games are requires to make any >>>>>>sort of statisticdal statement that engine X is better than engine Y. >>>>>> >>>>>>I concede this point. >>>>> >>>>>If you concede this point you don't understand. There is no magic number like >>>>>200 or 2000. The score must be considered. Here is an example: >>>>> >>>>>A score of 17 - 3 in a 20 game match has a certainty of over 99% that the winner >>>>>of the match is stronger then the loser. >>>>> >>>>>A 100 game match ending 55 - 45 only has a 81% chance that the winner of the >>>>>match is the stronger program. >>>>> >>>>>A 200 game match ending 106 - 94 only has a 78 % chance that the winner is >>>>>stronger then the loser. >>>> >>>> >>>>Nothing you have said is really correct because you have ignored the significant >>>>effect of draws in a match. >>> >>>The percentage of draws doesn't matter at all when it is about the conclusion >>>which program is strongest based on the above match results. >>> >>>This has been shown by Remi Coloum and explained in multiple posts >>>here(unfortunately the search engine hasn't found a new home yet). >>> >>>6-0 with 0 draws and 6-0 with 1000 draws has the exact same prediction value >>>when it is about the question which engine is stronger based on a match result. >> >>In this case, the number of decisive games (w+L=6) and margin of victory (w-L=6) >>is the same in both cases so the conclusion they have equal value is correct. >> >> ------------------------------- >> >>In the examples given before, the number of decisive games depends on the number >>of draws e.g. +17-3=0 and +14-0=6 are not of equal value since the number >>decisive games are not equal. >> >>Let's take a more obvious example. Let's say we play a 1000 game match and I win >>by +20-0=980. I only score 51%, but if we then play a short match, your chances >>of winning such a match is virtually zero, since the longer match has clearly >>demonstrated you couldn't win a game if your life depended on it. > >But if you team needed a half point for you to win the Olympias, this is match >up you wanted - a half point is a "shoo in" and you are the champs. Sometimes a >draw is more important than a win and (in the example I used) is just as good as >a win. > >Let's call the losing program "drawmaster" > > > 98% of the games will end in draw - a coinflip that lands on the edge? > > > > >> >>Now compare this with the alternative possibility. We play a 1000 game match and >>I win +510-490=0. Again 51%. Now we play a short match afterward, the match >>outcome will be very nearly a virtual coin flip. > >Let's call this losing program "win_or_die" > >> >>The first match is very convincing in demonstrating superiority. It is just as >>effective as +20-0=0 is as per Remi. > >You may think so, but at the the end of the day, Dr Elo will have program >"drawmaster" rated exactly the same as "win_or_die" --- and ratings are what we >were talking about here. Which program you may want to use may be based on >whether you need the win or a draw, if you need the draw , go with drawmaster, >if you need the full point , your chances are better with "win_or_die" . Ratings are not what I was responding to. Among the many erroneous things Mike Young said, "A 100 game match ending 55 - 45 only has a 81% chance that the winner of the match is the stronger program." This is a very specific statement dealing with whether a given player is better or not. Nothing to do with ratings in that statement. He _cannot_ provide a figure like "81%" without consdiering the percentage of games ending in draw. That's the type of mistake I directed myself towards. > > >> >>The second match is very unconvincing in demonstrating my superiority. It showed >>a game between us is a virtual coin flip. >> >>Draws matter a lot, but you need to understand just how. I'm very familiar with >>what Remi has said on this and it was quite correct. The trouble is people >>misunderstand what he has said. >> >>If you have understood the above, you will then understand that my remark to >>Mike Young was right on the money. > >I understand the above, but you are mixing apples and oranges and in the context >of the discussion taking place, your post was not on the money. It's really a >different subject (imo) and you just added unneeded confusion to a discussion. > I'm baffled as to why you think I'm mixing apples and oranges. I think you need to read through the thread again more carefully. If you do, you will find I cleared away some misconceptions rather than "...added unneeded confusion..."
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