Author: Sandro Necchi
Date: 23:07:08 01/06/04
Go up one level in this thread
On January 06, 2004 at 04:13:21, Sandro Necchi wrote: >On January 04, 2004 at 19:22:43, Ricardo Gibert wrote: > >>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. > >Well, if referred to 2 chess programs playing each other, this figure may be >optimistic/not true. >A better figure based on not to many games (<300) would be better with at least >6 different opponents. >There are cases where a program performs quite well against another one, but >does not so well against other programs. The result could change the final >figure more than you think. > >Sandro Sorry, I was not precise enough, so to let everybody understand I will try to be more clear: the percentage of a program to be stronger than another in a single match score 55 to 45 is about 20% and not 81% I do not care about statistic, but about real figure based on many tests and experience. So if you are interested to know how correct the result is than you get 20%. The reason is that if you look at the games you quite probably will find variation which scored quite well (or quite bad), thus putting a big weight on the final score. This is why it is better to make the same test against other chess programs; at least against other 5. There are only 2 ways to know if a program is better than another one: 1. To make a huge amount of games against several opponents; at least 1000 games. This everybody can do. 2. To look at the games and analyze them. You need to be a strong player to do this and/or to know chess programs a lot as well. Sandro > >>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..."
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.