Fischerle

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Fischerle,
aJava-based chess engine that has been developed byRoland Stuckardt. Fischerle implements theUCI protocol. It is recommended to employ it from within theArena environment. Additionally, Fischerle has an ownGUI providing supplementary configuration and testing features; in principle, it can thus be used independently of UCI based chess GUIs. Fischerle is available for download at its author's web pages .

Technology

Fischerle’s representation of chess positions is based on therotated bitboard model. Fischerle employs some well-known techniques of enhancedalpha-beta minimax search:

Transposition table

Evaluation cache

Promotions

7th rank Passed pawn extensions

Check evasions only by a singular / a few moves

Winning recaptures

Singular extensions (restricted implementation that doesn't apply atCut nodes and that considers onlytransposition table moves as singularity candidates the value of which is marked there as exact or lower bound)

extension by several plies at the very moment apawn endgame is reached

Tactically painlessreductions according to theenhanced model suggested byErnst A. Heinz

Adaptive Null Move Pruning

Extended Futility Pruning

Limited Razoring

Late Move Reductions
Interior node recognition similar to Heinz’s proposal^[1]
Dedicated scoring functions for some particularendgame types

The staticevaluation parameters of Fischerle are amenable to external finetuning based on a concept of so-called efb (evaluation factor block) files, thus enabling the user to influence, within certain bounds, Fischerle’s playing style (e. g. to prefer closed positions, etc.). Fischerle comes with its own, smallopening book, covering about 220K positions and some 540K moves. Fischerle supportspondering via itsUCI interface.

Latest Version

Fischerle0.9.80 SE^[2] - a slightly more aggressive forwardpruning scheme is now applied;quiescence search has been mildly refined (adding, in particular,delta pruning); the piece value assigned tobishops and thebishop pair bonus have been slightly reduced;king safety ealuation has been refined; the mate approaching scheme has been enhanced.

Etymology

Die Blendung byDoris Neidl^[3]

"Ein Mensch, was ka Schach spielt, ist ka Mensch"^[4]

Auto-da-Fé

Fischerle^[5] is named after a famous character ofElias Canetti’s novel„Die Blendung“ („Auto-da-Fé“)^[6]^[7] , which plays inVienna^[8] around protagonistPeter Kien, a middle-aged philologist andSinologist:Siegfried Fischerle^[9] , aJewish^[10]hunchbacked dwarf andpander, is achess addict whose dream is it to go to America to challenge chess championJosé Raúl Capablanca in order to get rich and famous. Canetti wrote his novel in the years 1930/31, coincidentally more than one decade beforeNazi German Oberfeldwebel Siegfried Fischer was decorated with theKnight's Cross of the Iron Cross, Jewish artist and poetPeter Kien died inAuschwitz concentration camp, and more than two decades before chess geniusBobby Fischer entered the international chess scene^[11] .

Fischers Fritz

The Germantongue-twister "Fischers Fritz fischt frische Fische. Frische Fische fischt Fischers Fritz." (Fisher's Fritz fishes fresh fish, fresh fish are fished by fisher's Fritz) is not related toFritz Fischer but may be to Fischerle's famous brotherFritz?