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Created page with "'''Home * Search * Selectivity * Pruning * Null Move Pruning * Double Null Move''' '''Double Null Move''',<br/> a Null Move Pruning technique pr..."
'''[[Main Page|Home]] * [[Search]] * [[Selectivity]] * [[Pruning]] * [[Null Move Pruning]] * Double Null Move'''
'''Double Null Move''',<br/>
a Null Move Pruning technique proposed by [[Vincent Diepeveen]] in 1997 <ref>[https://groups.google.com/d/msg/rec.games.chess.computer/PrN_AXwYV_4/UXU5x67UaoQJ Re: Null move?] by [[Vincent Diepeveen]], [[Computer Chess Forums|rgcc]], October 11, 1997</ref>, that allows two consecutive [[Null Move|null moves]] with common [[Depth Reduction R|depth reduction R]] in a row. Provided that the [[Depth|depth]] or distance to the horizon is big enough to recognize a possible [[Zugzwang|zugzwang]] 2R+2 plies shallower, and the first null move is refuted by the second one, its aim is to make NMH zugzwang aware. Double Null Move is used in [[Diep]] <ref>[https://www.stmintz.com/ccc/index.php?id=123156 Pseudo C code for double nullmove + PVS] by [[Vincent Diepeveen]], [[CCC]], August 06, 2000</ref>, and was widely discussed in [[Computer Chess Forums|computer chess forums]] <ref>[https://groups.google.com/d/msg/rec.games.chess.computer/i4NWIfd5CWc/InTKKFrT8YsJ Searching correctly with the Nullmove ==> no zugzwang problems anymore] by [[Vincent Diepeveen]], [[Computer Chess Forums|rgcc]], October 23, 1997</ref>, and overall recognized as a great idea <ref>[https://www.stmintz.com/ccc/index.php?id=161000 Re: Double Nullmove] by [[James Swafford]], [[CCC]], March 30, 2001</ref> . While likely too expensive in the [[Middlegame|middlegame]] where zugzwang is rare, and still not recommend for [[Pawn Endgame|pawn endings]] <ref>[https://www.stmintz.com/ccc/index.php?id=123223 Re: double nullmove??] by [[Vincent Diepeveen]], [[CCC]], August 06, 2000</ref>, it might be well applied in other [[Endgame|endgames]].
=See also=
* [[Fail-High Reductions]]
* [[Internal Iterative Deepening]]
* [[Null Move]]
* [[Null Move Observation]]
* [[Null Move Reductions]]
* [[Null Move Test-Positions]], where Null Move may fail due to zugzwang
* [[Zugzwang]]
* [[Null Move Pruning#ZugzwangVerification|Zugzwang Verification]]
=Forum Posts=
* [https://groups.google.com/d/msg/rec.games.chess.computer/PrN_AXwYV_4/UXU5x67UaoQJ Re: Null move?] by [[Vincent Diepeveen]], [[Computer Chess Forums|rgcc]], October 11, 1997
* [https://groups.google.com/d/msg/rec.games.chess.computer/i4NWIfd5CWc/InTKKFrT8YsJ Searching correctly with the Nullmove ==> no zugzwang problems anymore] by [[Vincent Diepeveen]], [[Computer Chess Forums|rgcc]], October 23, 1997
* [https://www.stmintz.com/ccc/index.php?id=123156 Pseudo C code for double nullmove + PVS] by [[Vincent Diepeveen]], [[CCC]], August 06, 2000
* [https://www.stmintz.com/ccc/index.php?id=160954 Double Nullmove] by [[David Rasmussen]], [[CCC]], March 30, 2001
* [https://www.stmintz.com/ccc/index.php?id=179604 Double Null move?] by [[Steve Maughan]], [[CCC]], July 13, 2001
* [https://www.stmintz.com/ccc/index.php?id=225990 Double Nullmove] by [[Andreas Herrmann]], [[CCC]], April 25, 2002
* [https://www.stmintz.com/ccc/index.php?id=373804 double null move help] by [[Daniel Shawul]], [[CCC]], July 04, 2004
* [http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=283903&t=29176 Re: Search-algorithm] by [[Vincent Diepeveen]], [[CCC]], August 01, 2009
: [http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=283906&t=29176 Re: Search-algorithm] by [[Don Dailey]], [[CCC]], August 01, 2009
* [http://www.talkchess.com/forum/viewtopic.php?t=56272 Why not two consecutive null moves ?] by [[Henk van den Belt]], [[CCC]], May 07, 2015
=References=
<references />
'''[[Null Move Pruning|Up one level]]'''
'''Double Null Move''',<br/>
a Null Move Pruning technique proposed by [[Vincent Diepeveen]] in 1997 <ref>[https://groups.google.com/d/msg/rec.games.chess.computer/PrN_AXwYV_4/UXU5x67UaoQJ Re: Null move?] by [[Vincent Diepeveen]], [[Computer Chess Forums|rgcc]], October 11, 1997</ref>, that allows two consecutive [[Null Move|null moves]] with common [[Depth Reduction R|depth reduction R]] in a row. Provided that the [[Depth|depth]] or distance to the horizon is big enough to recognize a possible [[Zugzwang|zugzwang]] 2R+2 plies shallower, and the first null move is refuted by the second one, its aim is to make NMH zugzwang aware. Double Null Move is used in [[Diep]] <ref>[https://www.stmintz.com/ccc/index.php?id=123156 Pseudo C code for double nullmove + PVS] by [[Vincent Diepeveen]], [[CCC]], August 06, 2000</ref>, and was widely discussed in [[Computer Chess Forums|computer chess forums]] <ref>[https://groups.google.com/d/msg/rec.games.chess.computer/i4NWIfd5CWc/InTKKFrT8YsJ Searching correctly with the Nullmove ==> no zugzwang problems anymore] by [[Vincent Diepeveen]], [[Computer Chess Forums|rgcc]], October 23, 1997</ref>, and overall recognized as a great idea <ref>[https://www.stmintz.com/ccc/index.php?id=161000 Re: Double Nullmove] by [[James Swafford]], [[CCC]], March 30, 2001</ref> . While likely too expensive in the [[Middlegame|middlegame]] where zugzwang is rare, and still not recommend for [[Pawn Endgame|pawn endings]] <ref>[https://www.stmintz.com/ccc/index.php?id=123223 Re: double nullmove??] by [[Vincent Diepeveen]], [[CCC]], August 06, 2000</ref>, it might be well applied in other [[Endgame|endgames]].
=See also=
* [[Fail-High Reductions]]
* [[Internal Iterative Deepening]]
* [[Null Move]]
* [[Null Move Observation]]
* [[Null Move Reductions]]
* [[Null Move Test-Positions]], where Null Move may fail due to zugzwang
* [[Zugzwang]]
* [[Null Move Pruning#ZugzwangVerification|Zugzwang Verification]]
=Forum Posts=
* [https://groups.google.com/d/msg/rec.games.chess.computer/PrN_AXwYV_4/UXU5x67UaoQJ Re: Null move?] by [[Vincent Diepeveen]], [[Computer Chess Forums|rgcc]], October 11, 1997
* [https://groups.google.com/d/msg/rec.games.chess.computer/i4NWIfd5CWc/InTKKFrT8YsJ Searching correctly with the Nullmove ==> no zugzwang problems anymore] by [[Vincent Diepeveen]], [[Computer Chess Forums|rgcc]], October 23, 1997
* [https://www.stmintz.com/ccc/index.php?id=123156 Pseudo C code for double nullmove + PVS] by [[Vincent Diepeveen]], [[CCC]], August 06, 2000
* [https://www.stmintz.com/ccc/index.php?id=160954 Double Nullmove] by [[David Rasmussen]], [[CCC]], March 30, 2001
* [https://www.stmintz.com/ccc/index.php?id=179604 Double Null move?] by [[Steve Maughan]], [[CCC]], July 13, 2001
* [https://www.stmintz.com/ccc/index.php?id=225990 Double Nullmove] by [[Andreas Herrmann]], [[CCC]], April 25, 2002
* [https://www.stmintz.com/ccc/index.php?id=373804 double null move help] by [[Daniel Shawul]], [[CCC]], July 04, 2004
* [http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=283903&t=29176 Re: Search-algorithm] by [[Vincent Diepeveen]], [[CCC]], August 01, 2009
: [http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=283906&t=29176 Re: Search-algorithm] by [[Don Dailey]], [[CCC]], August 01, 2009
* [http://www.talkchess.com/forum/viewtopic.php?t=56272 Why not two consecutive null moves ?] by [[Henk van den Belt]], [[CCC]], May 07, 2015
=References=
<references />
'''[[Null Move Pruning|Up one level]]'''
