Nasir_Shaheen wrote:bob wrote:Spock wrote:For the record then - are you accusing Vas of being a liar when he says Rybka is 100% original source code ?
If he says Rybka 1 has no fruit code whatsoever, then I would certainly say that. If he simply says "Rybka has no fruit code" that is a different statement, since I have not personally looked at any disassembled Rybka 2 or 3 code at all.
But rest assured, Rybka 1 does have code from Fruit. Unless you somehow believe that two different people can write identical code completely independently, for a program as complex as chess. Students don't write identical code for assignments that are 100-200 lines long. Or even for assignments 50 lines long. Statistically, I suppose it _could_ happen. Just as I could flip 1,000,000 heads in a row. But it is not very likely at all.
Hi Hyatt , Some young programmer Zach Wegner has given some points in rybka forum to show that rybka 1 is based on fruit , the points he given are following :
" Rybka's piece square tables are generated from the same code as Fruit's (same KnightRank, etc. constants, but different KnightRankOpening weights)
Rybka's pawn evaluation is virtually identical to Fruit's (different weights again, candidate pawns and backward pawns have a very slightly different formulation)
Rybka's passed pawn evaluation is virtually identical to Fruit's (same bonuses using the quad array {0...,26,77,154,256}, only difference is weights and free_passer split into 3 separate bonuses and based on rank)
Rybka's piece evaluation is virtually identical to Fruit's (different weights only)
Rybka's king shelter evaluation is virtually identical to Fruit's (different weights again, king square generalized to C1, E1, or G1 to store in the pawn table, and a slightly different formula for shelter_file()/storm_file())
Rybka's king safety evaluation is virtually identical to Fruit's (different weights for KingAttackWeight, KingAttackUnit)
Rybka's "pattern" evaluation is virtually identical to Fruit's (different weights, TrappedBishop is not halved for A6/H6).
I have confirmed all of this from reverse engineering Rybka 1, though anyone can see for themselves by looking at *****. Rybka's entire evaluation is basically an optimized and tuned bitboard translation of Fruit's, with Fruit's material evaluation replaced by the infamous lookup table. EVERY single evaluation term in Rybka 1, except for the material imbalance table, appears in Fruit. If everyone wants to consider that "original", then computer chess is really dead.
And this is only the evaluation. There are many more similarities.. "
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As i don't have any back ground in Programming so I want your openion on these points . Are these points valid ?
If YES , then there is not doubt that Vas has violated the GPL.
Also in this case reverese engineering the current Rybka is absolutely legal.