Rival

a chess engine written by Chris Moreton and Russell Newman in C++, starting in 1992 as MS-DOS program with an own GUI, before being rewritten for Windows as WinBoard compatible engine (NewRival) a couple of years later. The UCI protocol was implemented in 2006 as //Rival UCI 1.18 for Windows//, while the current Rival engine was ported to Java as used in the Android application. DOS and Windows versions are available as source code. Further, Rival is able to play various chess variants like Kinglet, Losing Chess, and Shatranj. || toc =Description= Rival is described in detail on the //redhotpawn// sites. Rival for Java uses bitboards with big-endian rank-file mapping. It determines sliding piece attacks with magic bitboards.
 * Home * Engines * Rival**
 * [[image:Ye_Eifl_sunset.jpg link="http://en.wikipedia.org/wiki/File:Ye_Eifl_@_sunset.jpg"]] ||~ || **Rival**, (Rival Chess, NewRival)
 * The Rivals ||~ ||^ ||

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Rival applies PVS negamax alpha-beta with transposition table, killer heuristic and quiescence inside an iterative deepening framework.

Evaluation
The evaluation function calculates scores of both sides, and returns the score difference of the side to move minus the side not on the move in negamax manner, considering pawn structure, various piece terms, and king safety. A quote from Rival's //Static Board Evaluation// site :

=Sreenshots=

DOS & Windows

 * [[image:rivaldos.gif link="http://www.redhotpawn.com/rival/"]] ||~ || [[image:rivalwin.jpg link="http://www.redhotpawn.com/rival/"]] ||
 * Rival for DOS ||~ || Rival for Windows ||

Android

 * [[image:RivalForAndroid.jpg link="https://play.google.com/store/apps/details?id=com.netadapt.rivalchess"]] ||
 * JavaRival, UCI engine for Android ||

=See also=
 * Geography
 * Star Trek

=Forum Posts=
 * [|Rival Chess 1.5.041] by Chris Moreton, rgcc, November 03, 1998
 * [|Rival Chess] by Đorđe Vidanović, rgcc, November 04, 1998
 * [|History Heuristic on its own] by Chris Moreton, CCC, January 16, 1999 » History Heuristic
 * [|Rival Chess advances to Winboard Championships!] by Daniel Chancey, CCC, March 24, 2000
 * [|Rival Chess 1.0.1 and 1.0.3] by Tony Mokonen, CCC, July 29, 2017

=External Links=

Chess Engine

 * [|GitHub - chris-moreton/rival-chess-android-engine]
 * [|GitHub - chris-moreton/rival-chess-dos]
 * [|Rival Chess Engine]
 * [|Rival Chess Engine - Magic Bitboards]
 * [|Rival Chess Engine - Downloads]
 * [|Rival Chess Free - Android Apps on Google Play]
 * [|Rival Chess - Red Hot Pawn]
 * [|Rival 1.18] in CCRL 40/40
 * [|Defending Humanity's Honor] by [|Tim Krabbé], see game NewRival - Faile with 493 moves, and playing 402 moves with bare kings!

Chess Programming
> [|Negamax] > [|Alpha-Beta Pruning] > [|Move Ordering] > [|Quiescence] > [|Transposition/Refutation Tables] > [|Killer Heuristics] > [|Minimal Window] > [|Timing Moves] > [|Draw Scoring] > [|Static Board Evaluation] > [|Openings]
 * [|Introduction]

Misc

 * [|rival - Wiktionary]
 * [|Rival (disambiguation) from Wikipedia]
 * [|Rivals (Star Trek: Deep Space Nine) from Wikipedia]
 * [|Yr Eifl - The Rivals from Wikipedia]

=References= =What links here?= include page="Rival" component="backlinks" limit="30"
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