Changes

We rapidly then improved Echec and the version 1.5 finished second of the [[WMCCC 1990=|1990 World Microcomputer Chess Championship]]. Echec even should have win the tournament since it had a winning position against [[Mephisto Lyon|Mephisto]] but since our new program [[Cumulus]] was having visibly a bad bug and that we were not sure that the Bug was not in common code shared by Echec, we were happy with a draw and set the [[Contempt Factor|contempt factor]] to +4. When [[Richard Lang]] saw that, he set Mephisto's Contempt Factor to -2, laughing. Well of course, we were all thinking that Mephisto should win... Mephisto took a poisoned pawn and then came into a losing position. Echec tried to [[Repetitions|repeat the position]], and Mephisto did not want at first but its score went bellow -2 and finally the programs drew !

Written by Marc-François Baudot, in association with Jean-Christophe Weill of [[Cumulus]] (they collaborate on ideas and code, but have different programs reflecting their different opinions and experiments. Échec's [[Evaluation functionFunction|evaluation function]] includes [[Piece-Square Tables|piece placement]] relative to [[Pawn Structure|pawn structure]], pawn structure itself, taking into account of which major or minor pieces are on the board, [[Mobility|mobility]], etc. (Marc reports that this was badly tuned, with the result that Échec's positional play was poor in the tournament). [[Search]] techniques include [[Check Extensions|check extensions]] but not [[Singular Extensions|singular extensions]], plus extensions for some mate threats and [[Promotions|promotion]].