Author: David Rasmussen
Date: 18:43:59 12/06/01
Go up one level in this thread
On December 06, 2001 at 20:17:24, Sune Fischer wrote: >On December 06, 2001 at 19:31:13, David Rasmussen wrote: > >>>Okay, then try and calculate the odds of getting 300 collisions out of 10000 >>>using "danish: tilbagelægning" from a pool of 4 billion, those odds are >>>astronomically small for sure, so something strange _is_ happening. >>> >> >>I don't necesarily think that that is an accurate model for the situation here. >>I trust my emperical data. It's the model that needs to be fixed IMO. > >I don't see why that should be any more accurate. The model is very simple, the >program is not, I have one line of math, you have a hundred of lines of code. >You need to point out at least one flaw in the model if you want to dispute it. >The fact that it is a simple model is not enough to say it is incorrect. I've >have used upper bounds on all the numbers, which mean they should describe the >worst case senario. For one thing, I haven't checked whether your numbers are reasonable, as you have also mentioned. >If you and Bob have 10 times as many pawn positions, then there is nothing >strange at all with you having collisions, but since you won't test for that we >have no way of knowing. > I will test that for you. I told you that. Do you read my posts? >>>>I don't. This is not hard evidence. This is theory based on false assumptions >>>>and a wrong model. >>> >>>Feel free to name 1! :) >>> >>>>Hard evidence is hundreds (or thousands or millions if you >>>>want) of pairs of positions that has the same pawn hash signature in Crafty. >>>>That is by definition a collision. >>> >>>Maybe so, but you think you are proving that 32 bit keys are no good, when all >>>you are proving is that you have _some_ bug IMO. >>> >> >>Then a lot of us have the same bug. We see exactly the same behavior. Same >>rates, bursts of clusters of collisions etc. > >Who is the rest of you? The others who have posted that they have collisions too. >Can't any one of you test how many positions you get? >That number is the key to the mystery. > I will, as I told you. >>>Me too, espicially since it was him who talked Bob into it in the first place;) >> >>He's not really sure. > >He got the idea from Bruce, yes? > He's not sure. Read his posts. >>>But you've seen my results and they confirm "my theory", so that would be a very >>>strange double bug in any case. >>> >> >>Your program stands out, then. > >From yours? From the others who have experienced the same things. Read the posts. >Very small set to do statistics by. > >>>>Talk to Hyatt about that. As for me, I have tried many different PRNG's. All >>>>with similar results. >>> >>>It is very strange indeed, but 32 bit seems to be working for me (for what ever >>>reason), so I will change from 64 to 32 soon :) >>> >>>-S. >> >>That's understandable. Just be sure you don't have a buggy test, as you are >>implying that I have. >> >>/David > >The test may show collisions, but then the question is why you get them. >I can think of only two reasons: >1. You have a bad zobrist table >2. You have many more positions than me. > >I vote for number 2, but obviously I can't prove that since your numbers seem to >be a well guarded secret. > >-S. At least we agree on that :) I go for number 2 also. But we'll see.
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