Editing Irregular chess opening

{{Short description|Chess opening that is considered unusual}}
{{algebraic notation}}
In [[chess]], an '''irregular opening''' is an [[chess opening|opening]] considered unusual or unorthodox. In the early 19th century the term was used for any opening not beginning with 1.e4 e5 (the [[Open Game]]) or 1.d4 d5 (the [[Closed Game]]). As opening theory has developed and openings formerly considered "irregular" have become standard, the term has been used less frequently.<ref name=Oxford>Hooper & Whyld, ''The Oxford Companion to Chess'', Oxford University Press, 1996, p 182, "Irregular opening, in the early 19th century any opening that did not begin with 1.e4 e5 or 1.d4 d5. However, Jaenisch said, 'As this distinction is purely arbitrary, and unfounded on principle, we cannot ourselves adopt it. We distinguish all the openings as "correct", or else as "incorrect" or "hazardous".' Since then many so-called irregular openings have become standard play. These and many other openings have acquired names and the term irregular opening has gradually fallen into disuse."</ref>

Because these openings are not popular with chess players, the standard opening references such as ''[[Modern Chess Openings]]'' (MCO) and ''[[Encyclopaedia of Chess Openings]]'' (ECO) do not cover them in detail.

==Usage of the term==
While the term has frequently been used in chess literature, its meaning has never been precise and has varied between writers.

One of the earliest references to "irregular openings" in chess literature was made by [[William Lewis (chess player)|William Lewis]] in his 1832 work ''Second Series of Lessons on the Game of Chess''. Lewis classified openings under the headings "[[Bishop's Opening|King's Bishop's Game]]" (1.e4 e5 2.Bc4), "[[King's Knight Opening|King's Knight's Game]]" (1.e4 e5 2.Nf3), "[[Centre Pawn Opening|Queen's Bishop's Pawn Game]]" (1.e4 e5 2.c3), "[[King's Gambit]]" (1.e4 e5 2.f4), "[[Queen's Gambit]]" (1.d4 d5 2.c4) and "Irregular Openings" (all other openings). Lewis comments that the irregular openings are "seldom played, because they are generally dull and uninteresting". Among the openings he analyzes under this heading are the [[French Defence]] and [[English Opening]] (both now considered standard), [[Bird's Opening]] and a few [[Closed Game|1.d4 d5]] lines without the Queen's Gambit. Lewis assigns no names to these openings.<ref name=Lewis1834>[[William Lewis (chess player)|William Lewis]], [https://books.google.com/books?id=kFBiAAAAcAAJ ''Second Series of Lessons on the Game of Chess''], Simpkin & Marshall, London 1832</ref>

[[Carl Jaenisch]], who was an early advocate of the French and [[Sicilian Defence|Sicilian]] defences, rejected this use of the term "irregular", saying that openings should rather be classified as "correct", "incorrect" or "hazardous".<ref name=Jaenisch>[[Carl Jaenisch]], [https://books.google.com/books?id=tP1dAAAAcAAJ&pg=PA14 Jaenisch's Chess Preceptor: A New Analysis of the Openings of Game], Longman, Brown, Green & Longman, London, 1847 (original in French, St. Petersburg 1843)</ref> In ''The Chess-Player's Handbook'' (1847), for many years the standard English-language reference book on the game of chess, [[Howard Staunton]] accepted Lewis's overall classification system while tacitly acknowledging Jaenisch's objections. He wrote "Those methods of commencing the game, in which the first or second player moves other than (1.e4 e5 or 1.d4 d5) are usually designated "Irregular". Without assenting to the propriety of this distinction, I have thought it advisable, for the sake of perspicuity, to adopt a general and well known classification in preference to arranging these peculiar ''débuts'' under separate and less familiar heads." Under this heading, Staunton considers the French Defence, Sicilian Defence, [[Scandinavian Defence]], [[Owen's Defence]], [[Dutch Defence]], [[Benoni Defence]], Bird's Opening and English Opening.<ref name=Staunton>Howard Staunton, [https://books.google.com/books?id=Zu0IAAAAQAAJ&pg=PA368 ''The Chess-Player's Handbook''], Henry G. Bohn, London 1847</ref>

==Strategic considerations==
{{Unreferenced section |date=May 2024}}
Irregular openings are usually considered somewhat weaker than standard openings if both players play "perfectly".  An element that many irregular openings share in common to their favor, however, is that many players have not studied the resulting positions in depth.  As such, they can be a useful tool when played intentionally, similar to [[List of chess traps|chess traps]], to throw the other player off their preferred openings they've prepared for and played many times, and force the game onto a path that only the irregular opening player has studied.  This advantage can offset the theoretical weakness; even if the other player avoids any direct blunders, they may be forced to spend time deriving the correct move through personal analysis, rather than instantly knowing the "correct" reply from a memorized opening book.  In the same way, such strategies could be effective against older and weaker computer chess programs from the 1980s and 1990s: a chess program that heavily relied on memorized opening books from games of top players could be set adrift quickly by an irregular opening, and forced to calculate moves for itself.  Such tactics no longer work on modern chess programs, however, which are significantly stronger.

==Examples==

===Unusual first moves by White===
The vast majority of high-level chess games begin with either [[King's Pawn Game|1.e4]], [[Queen's Pawn Game|1.d4]], [[Zukertort Opening|1.Nf3]], or [[English Opening|1.c4]].<ref name=ChessBase>Randy Olson, [https://en.chessbase.com/post/popularity-of-chess-openings-over-time ''Popularity of chess openings over time''], ChessBase, 24 June 2014</ref> Also seen occasionally are [[King's Fianchetto Opening|1.g3]], [[Larsen's Opening|1.b3]], and [[Bird's Opening|1.f4]]. Other opening moves by White, along with a few non-[[transposition (chess)|transposing]] lines beginning 1.g3, are classified under the code "A00" by the ''[[Encyclopaedia of Chess Openings]]'' and described as "uncommon" or "irregular".<ref name="chessinformant">{{cite web | url=http://www.chessinformant.org/content/eco-codes.pdf | title=Encyclopaedia of Chess Openings Classification Code Index | publisher=chessinformant | access-date=6 July 2016 | archive-url=https://web.archive.org/web/20170829000056/http://www.chessinformant.org/content/eco-codes.pdf | archive-date=29 August 2017 | url-status=dead }}</ref><ref name="chessarch">{{cite web | url=http://www.chessarch.com/library/0000_eco/a00_a99.shtml | title=A00-A99 | publisher=chessarch | access-date=5 July 2016}}</ref> Although they are classified under a single code, these openings are unrelated to each other.

The openings classified as A00 are:
*1.[[b:Chess Opening Theory/1. a3|a3]] – [[Anderssen's Opening]]
*1.[[b:Chess Opening Theory/1. a4|a4]] – [[Ware Opening]]
*1.[[b:Chess Opening Theory/1. b4|b4]] – [[Sokolsky Opening]], also known as the Polish Opening or Orangutan Opening
*1.[[b:Chess Opening Theory/1. c3|c3]] – [[Saragossa Opening]]
*1.[[b:Chess Opening Theory/1. d3|d3]] – [[Mieses Opening]]
*1.[[b:Chess Opening Theory/1. e3|e3]] – [[Van 't Kruijs Opening]]
*1.[[b:Chess Opening Theory/1. f3|f3]] – [[Barnes Opening]], also known as Gedult's Opening
*1.[[b:Chess Opening Theory/1. g3|g3]] – [[King's Fianchetto Opening|King's Fianchetto Opening or Benko's Opening]]
*1.[[b:Chess Opening Theory/1. g4|g4]] – [[Grob's Attack]]
*1.[[b:Chess Opening Theory/1. h3|h3]] – [[Clemenz Opening]], or Basman's Attack
*1.[[b:Chess Opening Theory/1. h4|h4]] – [[Desprez Opening]], or Kadas Opening
*1.[[b:Chess Opening Theory/1. Na3|Na3]] – [[Durkin Opening]], also known as Durkin's Attack or the Sodium Attack
*1.[[b:Chess Opening Theory/1. Nc3|Nc3]] – [[Dunst Opening]]
*1.[[b:Chess Opening Theory/1. Nh3|Nh3]] – [[Amar Opening]], also known as the Paris Opening, Ammonia Opening, or Drunken Knight Opening

The [[Nimzowitsch-Larsen Attack]] (1.b3, ECO code A01) and [[Bird's Opening]] (1.f4, ECO codes A02–A03) have also been described as "irregular", particularly in older books.<ref name=Tartakower>[[Savielly Tartakower]] & Jules du Mont, [https://books.google.com/books?id=HW4WAwAAQBAJ&pg=PA651 ''500 Master Games of Chess''], Dover, 1952, p651</ref><ref name=Staunton />

===Unusual responses by Black===
Openings in which Black makes an unconventional response to 1.e4 are classified as B00 ([[King's Pawn Game]]).<ref name="chessinformant" /> Included in this code are:
*1.e4 a6 – [[St. George Defence]]
*1.e4 b6 – [[Owen's Defence]]
*1.e4 f6 – [[Barnes Defence]]
*1.e4 h6 – [[Carr Defence]]
*1.e4 Na6 – [[Lemming Defence]]
*1.e4 Nc6 – [[Nimzowitsch Defence]]
*1.e4 Nh6 – [[Adams Defence]]
*1.e4 a5 – [[Cornstalk Defence]]
*1.e4 b5 – O'Neill Gambit (loses pawn to 2. Bxb5)
*1.e4 f5 – [[Fred Defence]]
*1.e4 g5 – [[Borg Defence]]
*1.e4 h5 – [[Goldsmith Defence]]

Of these, 1...Nc6, 1...b6, 1...a6, and 1...g5 have received the most theoretical attention.<ref name=MCO>Nick de Firmian, [https://books.google.com/books?id=3xS_CAAAQBAJ&pg=PA543 ''Batsford's Modern Chess Openings''], 2014</ref> [[Tony Miles]] famously used 1...a6 to defeat [[Anatoly Karpov]].<ref name=Ottawa>Les Bunning, [https://news.google.com/newspapers?nid=2194&dat=19800628&id=MaMyAAAAIBAJ&sjid=g-4FAAAAIBAJ&pg=5891,3880942&hl=en Miles known for unorthodox style of play], Ottawa Citizen, 28 June 1980</ref>

==See also==
* [[List of chess openings]]
* [[Bongcloud Attack]]

==Notes==
{{reflist}}

==References==
*{{cite book
 | last1=Benjamin
 | first1=Joel
 | author-link1=Joel Benjamin
 | last2=Schiller
 | first2=Eric
 | author-link2=Eric Schiller
 | title=Unorthodox Openings
 | publisher=[[Macmillan Publishers (United States)|Macmillan Publishing Company]]
 | year=1987
 | isbn=0-02-016590-0}}
*{{cite book | author=Schiller, Eric | title=Unorthodox Chess Openings | publisher=Cardoza | year=2003 | isbn=1-58042-072-9}}
*{{Cite journal
 | last = Tamburro|first = Pete
 |date=August 2009
 | title = A Brief Chess Opening Glossary
 | journal = Chess Life for Kids
 | pages = 8–9
 }}

{{Chess}}

[[Category:Chess openings|*Irregular openings (chess)]]