Author: Dann Corbit
Date: 11:30:10 10/03/01
Go up one level in this thread
On October 03, 2001 at 06:23:01, Andreas Stabel wrote: >On October 02, 2001 at 13:39:08, Dann Corbit wrote: > >>On October 02, 2001 at 06:04:38, Andreas Stabel wrote: >> >>>On October 01, 2001 at 18:21:09, Dann Corbit wrote: >>> >>>>On October 01, 2001 at 18:11:10, robert flesher wrote: >>>> >>>>>It has been calculated that the four opening moves can be made in 197,299 ways, >>>>>leading to some 72,000 different positions. The approximate numbers of different >>>>>games possible is 25x10 to the power of 116. a number astronomically higher that >>>>>the number of atmos in the observable universe. This Quote was directly taken >>>>>from Guiness book of world records 1976 edition. WOW and this is why chess is so >>>>>damn hard. :) >>>> >>>>Unfortunately, they don't know what they are talking about. >>>>There are 197,281 different ways to make the 4 opening moves. >>>>There are 99,270 distinct positions at ply 4 (including e.p vulnerability). >>>>The other numbers are equally suspect. >>>>This has some interesting information: >>>>http://www.clark.net/pub/pribut/chessfaq.html >>>>Though the actual length of the longest possible game may be open to a bit of >>>>debate. I have seen slightly different figures given elsewhere. >>> >>>My program has generated the following table - which does not seem to match >>>your numbers very well. >>> >>>Table from opening position: >>> | | Unique nodes | Unique nodes II Unique nodes | Factor | >>>Ply| Total # nodes | ep = pawn two | ep = oppositeII ep = Only if | prev. | >>> | | | pawn can hit II ep is legal | row | >>>---+---------------+---------------+--------------II---------------+--------| >>> 0 | 1 | 1 | 1 II 1 | | >>> 1 | 21 | 21 | 21 II 21 | 21.00 | >>> 2 | 421 | 421 | 421 II 421 | 20.05 | >>> 3 | 9323 | 8023 | 5783 II 5783 | 13.74 | >>> 4 | 206604 | 109262 | 77796 II 77796 | 13.45 | >>> 5 | 5072213 | 1351950 | 898812 II 898812 | 11.55 | >>> 6 | 124132537 | 15334851 | 10281864 II 10281862 | 11.44 | >>> 7 | 3320034397 | 160373323 | 106193912 II 106193643 | 10.33 | >>> 8 | 88319013353 | | II | | >>> 9 | 2527849247520 | | II | | >> >>It appears that the only thing that does not match is the unique positions. >>Here is my list of uniqe epd positions after 4 ply: >>ftp://cap.connx.com/pub/chess-engines/new-approach/r4.unq.bz2 >> >>Perhaps you could be so kind as to compare with what you generate and tell me >>where I went off. Be advised that some of the positions have "useless" e.p. >>markers, but that is demanded by the PGN standard. > >I've checked your file a bit and it seems very wrong to me. There are positions >missing like r1bqkb1r/pppppppp/2n2n2/1B6/4P3/8/PPPP1PPP/RNBQK1NR w KQkq - >which you will get afte the moves 1. e4 Nc6 2. Bb5 Nf6 I'll look at that one. >In addition the file contains a lot of duplicates like >r1bqkbnr/1ppppppp/2n4B/p7/3P4/8/PPP1PPPP/RN1QKBNR w KQkq - >r1bqkbnr/1ppppppp/2n4B/p7/3P4/8/PPP1PPPP/RN1QKBNR w KQkq a6 These positions are lexically different and demanded by the PGN standard. I will agree that the chess game won't play any different, but I mentioned that above.
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