View source for Selfmate

{{Short description|Type of chess problem}}

[[File:Vive_la_beaute_-_being_the_tinted_edition_of_a_problematic_work_called_the_Caduceus_-_DPLA_-_f17bd895abe606de2f3b5f2b1f16d4d2_(page_120).jpg | thumb | right | Example of selfmate]]
A '''selfmate''' is a [[chess problem]] in which [[White and Black in chess|White]], moving first, must force Black to deliver [[checkmate]] within a specified number of moves. Selfmates were once known as '''sui-mates'''.
{{algebraic notation|pos=toc}}

==Example==
The problem shown is a relatively simple example. It is a selfmate in two by [[Wolfgang Pauly]]<ref>[https://chess-problems-gr.blogspot.com/2008/05/selfmates-1.html Pauly selfmate]</ref><ref>{{Cite web |url=http://www.chess.it/libri/pauly.htm |title=W. Pauly |access-date=2010-01-03 |archive-date=2012-03-02 |archive-url=https://web.archive.org/web/20120302022850/http://www.chess.it/libri/pauly.htm |url-status=dead }}</ref> from ''The Theory of Pawn Promotion'', 1912: White moves first and compels Black to deliver checkmate on or before Black's second move.
{{Chess diagram
|tleft
|Wolfgang Pauly, 1912
|kl|bl|  |  |  |nl|  |  
|pl|  |pl|  |pd|  |pl|  
|  |  |  |  |  |pl|  |kd
|  |  |  |  |pl|  |  |pd
|  |  |  |  |  |  |  |pl
|  |  |  |  |  |  |  |  
|  |  |  |  |  |  |bl|  
|  |  |  |  |  |  |  |bd
|Selfmate in two
}}
{{clear}}
If White can leave Black with no option but to play Bxg2{{chessAN|#}}, the problem is solved. 
* White might try moving the bishop, but this is no good, as it will allow Black to play a non-capturing bishop move himself, delaying the mate beyond move two;
* Moving the knight allows Black to move the king, and White can no longer force Black to checkmate him;
* 1.e6{{chesspunc|?}} allows 1...exf6 and 2...f5;
* 1.f7? or 1.fxe7? allows 1...Kxg7;
* 1.g8=Q? or 1.g8=R? are no good after 1...Bxg2+ 2.Q/Rxg2;
* 1.g8=B? also fails, since after 1...exf6 2.exf6 Bxg2+ the bishop can interpose with 3.Bd5;
* 1.g8=N#{{chesspunc|??}} checkmates Black, which is entirely wrong.

The only move by which White can force Black to deliver checkmate on or before move two is: 
:'''1. c8=N'''

There are two variations: 
* '''1... exf6 2. exf6 Bxg2#''' is a selfmate;
* '''1... e6''' allows '''2. g8=B''' (the e6-pawn blocks 3.Bd5), forcing '''2... Bxg2#''' and selfmate.
Note that only a promotion to a knight works on move one: any other piece would be able to interpose after 1...Bxg2+.

==Record problems==
{{chess diagram-fen
|fen=6K1/1n6/2p5/p1P3n1/B3Q1pP/p4P1p/pb4pr/r1k4b
|align=tright
|header=Karlheinz Bachmann, 2006 <br />(version by Christopher Jeremy Morse)
|footer=White to play, selfmate in 203
}}
The current record for the longest selfmate problem is a selfmate in 203, composed by Karlheinz Bachmann and Christopher Jeremy Morse in 2006.<ref>{{cite journal |last1=Morse |first1=Christopher Jeremy|title=NINTH UPDATE OF CHESS PROBLEMS: TASKS AND RECORDS |journal=The Problemist |date=July 2006 |volume=20 |issue=480 |page=431 |url=https://theproblemist.org/mags.pl?type=tp}}</ref> The puzzle is based on a 1922 342-move composition by Ottó Titusz Bláthy, which was later found to be {{chessprobgloss|cooked}}.{{citation needed|date=August 2021}}

Prior to December 2021, the record for the longest selfmate problem was a 359-move problem, created by Andriy Stetsenko in 2016.<ref name="Award in Jubilee Tourney">{{cite web |title=Award in Jubilee Tourney |url=http://superproblem.ru/doc/tourneys/other/2016/SuperProblem-10_JT_FINAL_AWARD_eng.pdf |website=SuperProblem |access-date=12 August 2021 |ref=1}}</ref> Unfortunately, this problem was later found to be cooked, as a shorter solution exists.

==Variations==
A derivative of the selfmate is the ''[[reflexmate]]'', in which White compels Black to give mate with the added condition that if either player can give mate, they must (when this condition applies only to Black, it is a ''semi-reflexmate''). There is also the ''maximummer'', in which Black must always make the geometrically longest move available, as measured from square-centre to square-centre; although this condition is sometimes found in other types of problems, it is most common in selfmates. Another variation is the ''series-selfmate'', a type of [[seriesmover]] in which White makes a series of moves without reply, at the end of which Black makes one move and is compelled to give mate.
{{clear}}

==See also==
*[[Helpmate]]
*[[Zugzwang]], forcing a move (compulsion to move)

==References==
{{Reflist}}

==Further reading==
*{{cite book |first=Friedrich |last=Chlubna |title=Das Matt des weissen Königs |location=Vienna |publisher=Chlubna |year=1995 |isbn=3-9500310-3-0 }}{{Sps|date=May 2019}}

[[Category:Chess problems]]