Onno

was a commercial chess engine developed by Onno Garms, written in C++ and released in May 2009. After announcing the end of Onno's development in March 2011, Onno Garms revealed several ideas that made Onno stronger. The 32/64-bit Windows or 64-bit Linux executables communicate with a chess GUI via the UCI. || toc =Description=
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 * [[image:logo.png link="http://www.onnochess.com/index.html"]] ||~ || **Onno**,
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Basics
Onno uses a fixed shift variation of Magic bitboards to determine sliding piece attacks. Its static exchange evaluation considers alpha and beta. Evaluation features were tuned automaticly performing a Genetic algorithm. 

Search
Onno applies an iterative search along with PVS, null move pruning and verification search. Onno further uses a technique dubbed **bad pruning** similar to razoring. The idea is to apply a reduced search with a reduced window - if the search at depth d-3 says that one loses more then a pawn, it does not search the move with the current depth d.

Parallel Search
The MP version of Onno searches in parallel utilizing YBWC by following Rainer Feldmann's 1993 Ph.D. thesis //Game Tree Search on Massively Parallel Systems// using [|virtual messaging].

Node Types
Onno determines expected Node Types to perform IID not only at PV-nodes but also at expected Cut-nodes. Onno Garms gave following rules
 * The root node is a PV-node.
 * The first child of a PV-node is a PV-node
 * The further children are searched by a scout search as CUT-nodes
 * PVS re-search is done as PV-node
 * The first node of bad pruning is a CUT-node
 * The node after a null move is a CUT-node
 * The first node of null move verification is a CUT-node
 * Internal iterative deepening does not change the node type
 * The first child of a CUT-node is an ALL-node
 * Further children of a CUT-node are CUT-nodes
 * Children of ALL-nodes are CUT-nodes

=See also=
 * Given Name
 * Iterative Search in Onno

=Forum Posts=

2009

 * [|Magic with fixed shift] by Onno Garms, Winboard Forum, March 18, 2009
 * [|Onno 0.12] by Ted Summers, CCC, April 04, 2009
 * [|New commercial engine soon: Onno] by Jouni Uski, CCC, May 17, 2009
 * [|Onno 1.0 is now available] by Graham Banks, CCC, May 30, 2009
 * [|About becoming Commercial. The Onno Case] by Fernando Villegas, CCC, June 02, 2009
 * [|Onno 1-1-1 released] by Eduard Nemeth, CCC, August 30, 2009

2010

 * [|Onno MP beta has been released to customers] by Martin Thoresen, CCC, February 27, 2010
 * [|Re: DTS Structure] by Onno Garms, CCC, May 28, 2010 » Iterative Search in Onno

2011 ...

 * [|Development of Onno ends] by Onno Garms, CCC, March 13, 2011
 * [|Root node search] by Onno Garms, CCC, March 13, 2011 » Root
 * [|Software Engineering] by Onno Garms, CCC, March 13, 2011 » History Heuristic, Toga
 * [|Bad Pruning] by Onno Garms, CCC, March 13, 2011 » Pruning
 * [|On internal iterative deepening] by Onno Garms, CCC, March 13, 2011 » Internal Iterative Deepening, Node Types
 * [|Less null move pruning by trans map] by Onno Garms, CCC, March 13, 2011 » Null Move Pruning
 * [|Playing better moves in drawish positions (anti-0.00)] by Onno Garms, CCC, March 13, 2011 » Draw, Contempt Factor
 * [|On parallelization] by Onno Garms, CCC, March 13, 2011 » Parallel Search
 * [|Parameter tuning] by Onno Garms, CCC, March 13, 2011 » Automated Tuning
 * [|Memory-PV-Search] by Onno Garms, CCC, March 13, 2011 » Principal Variation Search
 * [|Move ordering by PST] by Onno Garms, CCC, April 16, 2011 » Piece-Square Tables, History Heuristic, Move Ordering
 * [|SEE with alpha beta] by Onno Garms, CCC, August 14, 2011 » Static Exchange Evaluation, SEE - The Swap Algorithm

=External Links=

Chess Engine

 * [|Onno Chess Software]
 * [|Computerschach, Interview mit Onno Garms] by Frank Quisinsky, December 25, 2009 (German)

Misc

 * [|Onno – Wikipedia.de] - [|Frisian] [|Given Name] (German)

=References= =What links here?= include page="Onno" component="backlinks" limit="80"
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