NoraGrace

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NoraGrace, a WinBoard compliant open source chess engine by Eric Oldre, written in C# and first released in June 2014 under the MIT License. NoraGrace is dedicated to Nora Grace Oldre who was taken from Eric and his wife unexpectedly a few days before she was due to be born.

=Description=

Board Representation
Like Sinobyl, NoraGrace relies on bitboards, and further has an 8x8 mailbox. It uses magic bitboards to determine sliding piece attacks - factors were calculated from sparse 64-bit randoms. BitScan is implemented via 32-bit De Bruijn multiplication to conditionally branch on low and high double words. Bitboard serialization applies the C# yield statement , which is further used in various move generation routines. NoraGrace's square mapping has ranks from 8 to 1 mapped to 0-7 at the big-end over files from 'a' to 'h', square zero is a8: NoraGrace's BERLEF Mapping

Search
NoraGrace applies negamax alpha-beta with transposition table and quiescence search inside an iterative deepening framework with aspiration windows, enhanced by adaptive null move pruning with verification search in the endgame, extensions if SEE > 0 for checks and pawns to 7th rank, futility pruning and LMR.

Evaluation
Evaluation takes game phases into account, using a tapered eval along with PhasedScore objects, interpreting the low and high 32-bit double words of a 64-bit long as two SIMD integers of an endgame and opening score. Beside other features, NoraGrace considers material, piece-square tables, king safety, cached pawn structure and mobility.

=See also=
 * Sinobyl

=Forum Posts=
 * New open source engine in C# - NoraGrace by Eric Oldre, CCC, June 20, 2014
 * NoraGrace 2.0 (c# engine) by Eric Oldre, CCC, November 22, 2014

=External Links=

Chess Engine

 * Ericoldre/NoraGrace-Chess · GitHub
 * Releases · ericoldre/NoraGrace-Chess · GitHub
 * NoraGrace in CCRL 40/15

Misc

 * List of Irish-language given names - Wikipedia

=References= Up one Level