Die unendliche Geschichte »Rybka/Fruit«, Kapitel 97

By Michael Scheidl Date 2013-10-07 01:36

Eigentlich interessiert mich dieser Käse längst nicht mehr, aber folgendes ist doch noch lesenswert:

Zitat:

"Every major evaluation ingredient is coded differently, mobility, king safety, passed pawns, double pawns, backward pawns, Rybka is missing Fruit's late endgame knowledge, Rybka has a material table - different from Fruit. Rybka does not contain Fruit's quad function, Rybka's trapped bishop evaluation is different, rook evaluation is different, bishop pair evaluation different and most importantly, Fruit evaluates in stages in a unique way whereas Rybka adds directly to its score (as every other program on the planet does).

Other key differences between Fruit and Rybka:

Time control is different
Fen parsing is different
Rybka extracts the mainline from the transposition table (TT), Fruit via the classic triangle table
Rybka 1.0 beta displays a mainline of maximum of 10 moves, Fruit produces much longer variations
Rybka uses a bitboard board representation whereas Fruit is mailbox
Rybka's pawn value is 3200 (which is unique), Fruit uses the classic value of 100
The order in the evaluations of Fruit and Rybka are not similar
Rybka has lazy evaluation, which is absent in Fruit
Futility pruning is different between the two programs
Rybka uses Late Move Reductions (LMR) whereas Fruit uses history reductions
Fruit uses a history table which is absent Rybka.
Fruit only has one evaluation table (king safety) while Rybka has many
The two programs have a different move format
Rybka does not handle promotions to minor pieces
The two programs have different hash table code
They have different handling of repetitions and the 50-move rule in search
Fruit maintains piece-lists which are not present in Rybka
Fruit maintains a pseudo "bitboard" for pawns, Rybka has the real thing.
Contrary to Fruit, Rybka needs to update 4 rotations of occupancy bitboard
Contrary to Fruit, Rybka updates a rough estimate of material balance with weights of 1:3:3:5:10 (in the evaluation this value is then corrected by a delta obtained from the material table)
Fruit has a 16*16 square mailbox, Rybka has an 8*8
The programs have different Zobrist hash keys
The programs have different user interface options

We found 35 indisputable differences (some of which are very fundamental), not counting the ones that are debatable such as the Piece Square Tables (PSTs) and the contents of the TT."

Ed Schröder in http://www.chessvibes.com/rybka-case-greatest-injustice-perpetrated-in-computer-chess-history-part-1 vom 1.10.2013

By Benno Hartwig Date 2013-10-07 07:51

Ed führt in Rybka-Forum immer noch eine faszinierend ausdauernde Rybka-Vas-Verteidigungs-Linie, mit für mich nicht immer nachvollziehbarer Argumentation.
Und Robert wird dort auch nicht Müde, seine Vorwürfe zu wiederholen und nach Möglichkeit zu belegen, auch nicht immer wirklich nachvollziehbar.
Diese Auseinandersetzung hat sich irgendwie verselbständigt, Vas hat vielleicht das Computerschachthema schon längst weit hinter sich gelassen.
Aber dort ist ein Biotop entstanden, welches aus diesem ewigen Thema heute vielleicht seine einzige Daseinsberechtigung gewinnt. Wem es Spaß macht...

Benno