Four-corner method: Difference between revisions

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{{Short description|Method of encoding Chinese characters}}

{{More citations needed|date=August 2009}}

[[File:four-corner method.svg|200px|right|thumb|The code of 法 ({{zh|p=fǎ}}; meaning "method/law/France") is an example of a fifth digit for an extra part: 3413₁ (丶十一丶_一). (The numbers refer to the code for the colored ''part'', not the order of entry (which is left to right, top to bottom.) ]]

The '''Fourfour-Cornercorner Methodmethod''' or '''four-corner system''' ({{zh|t=四角號碼檢字法|s=四角号码检字法|p=sì jiǎo hàomǎ jiǎnzì fǎ|l=four corner code lookup-character method}}) is a [[Chinese input methods for computers|character-input method]] used for [[Character encoding|encoding]] [[Chinese character]]s into either a computer or a manual typewriter, using four or five [[numerical digit]]sdigits per [[Character (computing)|character]]. The Four-Corner Method is also known as the '''Four-Corner System'''.

The four digits encode the shapes found in the four corners of the symbol, top-upper left to bottom-lower right. Although this does not uniquely identify a Chinese character, it leaves only a very short list of possibilities. A fifth digit can be added to describe an extra part above the bottom-lower right if necessary.

The four-corner method, in its three revisions, was supported by the Chinese state for a while, and is notfound in commonnumerous usageolder reference works and some still in Chinapublication. orThe Taiwansmall today,''Kangorin althoughSino-Japanese dictionariesDictionary'' by Yoneyama had a four-corner index withwhen it arewas availableintroduced in manythe bookshops1980s, andbut librariesit forhas thosesince whobeen needdeleted. orHowever, desireit tois learnnot orin usecommon usage today, although dictionaries using it are available. It is identified, in public opinion, with the time when many Chinese were illiterate and the language was not yet unified; more Chinese today use the dictionary to help them write, not read. But it is useful for scholars, clerks, editors, compilers, and especially for foreigners who read Chinese. In recent years it has achieved a new usage as a character input system for computers, generating very short lists to browse.

==Origin==

The Fourfour-Cornercorner Methodmethod was invented in the 1920s by [[Wang Yunwu]] (王雲五), the editor in chief at Commercial Press Ltd., China. It was based on experiments by [[Lin Yutang]] and others.{{Citation needed|date=April 2007}} Its original purpose was to aid telegraphers in looking up [[Chinese telegraph code]] (CST) numbers in use at that time from long lists of characters. This was mentioned by Wang Yunwu in an introductory pamphlet called "Sijiaohaoma''Four-Corner Jianzifa"Method'', published in 1926. Introductory essays for this pamphlet were written by [[Cai Yuanpei]] and [[Hu Shih]] wrote introductory essays for this pamphlet.

==Mnemonics==

The four digits used to encode each character are chosen according to the "shape" of the four corners of each character.{{clarify|date=October 2021}} In order, these corners are upper left, upper right, lower left and lower right. The shapes can be memorized using a Chinese poem thatcomposed by [[Hu Shih composed]], called ''Bihuahaoma Ge'' ({{Lang-zh|t=筆畫號碼歌|p=Bǐhuà hàomǎ gē|labels=no|l=stroke number song}}), as a "[[Mnemonic device|memory key]]" to the system:

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!Traditional

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|}

In the 1950s, [[lexicographer]]s in the [[People's Republic of China]] changed the poem somewhat in order to avoid association with Hu Shih, althoughwho thehad contentscriticized remainthe generally unchanged. For[[Chinese variousCommunist reasonsParty]], his name was "unmentionable" atalthough the timecontents theremain newgenerally version was composedunchanged. The 1950s version is as follows:

{|border="0" cellspacing="0" cellpadding="0" style="margin:0.5em;margin-left:2em;background:transparent"

|-

!Traditional

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* If the character is fenced by {{Linktext|囗}}, {{Linktext|門}} (门), or {{Linktext|鬥}}, the lower corners are used to denote what is inside the [[Radical (Chinese character)|radical]], instead of 00 for 囗 or 22 for the others. (e.g. the code for 回 is 6060)

There have been scores, maybe hundreds, of such numerical and alpha-numerical systems proposed or popularized (such as [[Lin Yutang]]'s "[[Lin Yutang's Chinese-English Dictionary of Modern Usage|Instant Index]]", [[A Chinese–English Dictionary#Content|Trindex]], Head-tail, [[Wang An]]'s ''Sanjiahaoma'', [[Jack Halpern (linguist)|Halpern]]); some Chinese refer to these generically as "''sijiaohaoma"'' (after the original pamphlet) though this is not correct.

==Versions==

Over time, the Fourfour-Cornercorner Methodmethod has gone through some changes.

===First Version===

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* Military code making (for handling the characters quickly)

The ''Wang Yun-wu Da Cidian (Wang Yun-wu Ta Tz'u-tien)' of 1928 was remarkable for its time, and although the pronunciations were very much in line with today's Standard Chinese, the lack of a phonetic index diminished its overall usefulness. The northern [[Mandarin Chinese|Mandarin]] pronunciations were given in the "[[Gwoyeu Romatzyh|Guoyu Luomazi]]", a romanization system devised by linguist [[Yuen Ren Chao|Zhao Yuanren]], as well as in [[Bopomofo|Mandarin Phonetic System (MPS or Bopomofo) ]] characters with a dotted corner for tone. It also delineated parts of speech, and all compounds were listed by the four-corner method as well. It was extremely modern. It used some arcane styles of characters as a citation form, and had a few errors and some important omissions.

The famed lexicographer and editor of ''[[Ciyuan]]'', Lu Erkui (Lu Er-k'ui), as well as other lexicographers, became early proponents of the Fourfour-Cornercorner Methodmethod. By 1931, it was used extensively by the Commercial Press to index virtually all classical reference works and collections of China, such as the ''Pei Wen Yun Fu'' and ''[[SikuComplete Quanshu|SiLibrary Kuof Quanthe ShuFour Treasuries]]'', as well as many modern ones.

Hospital, personnel and police records were organized just like the biographical indexes and dynastic histories of former times. For a while (Nash, Trindex, 1930), it seemed that theuse Kangof Xithe Bushou (K'ang-hsi Pu-shou)214 [[214Kangxi Radical Systemradicals]], leftintroduced byduring the Qing (Ch'ing) Dynastydynasty, was being replaced by the Fourfour-Cornercorner Methodmethod.

Internationally, Harvard and other universities were using the method for their book collections, and the [[Kuomintang|KMT]] Nanjing government (thein main political and governmental body prior to 1949)Nanjing seemed to have selected this numerical system as its standard. It was taught in primary schools to children in [[Shanghai]] and other locations during the late 1920s and throughout the 1930s, up to the outbreak of general war with [[Japan]] in 1937. The four-corner method was extremely popular in government education circles to promote spoken language unification until pronunciation-based systems became fashionable in the mid-1930s.

The Four-Corner Method was extremely popular in government education circles to promote spoken language unification until pronunciation-based systems became fashionable in the mid-1930s.

The first large-scale project to promote spoken language unification was in 1936: [[Wang Li (linguist)|Wang Li]]'s 4-volume Mandarin Phonetic System (MPS) entry, ''Guoyu Cidian (Kuo-yu Tz'u-tien)'. In 1949 it was re-edited into the MPS ''[[Hanyu Da Cidian]]'' with [[Kangxi Emperor|Kang Xi]] 214 radical index, and a small Four Corner dictionary was available as the ''Xin Sijiaohaoma Cidian'' of 1953. After 1949, limited use of MPS and the original Fourfour-Cornercorner Methodmethod continued underin the People's GovernmentRepublic of China, until the introduction of [[pinyin]] in 1958 and after. Today's Chinese dictionaries still contain MPS characters below each Pinyinpinyin class entry and sometimes in a phonetics chart in tables (''Xinhua Cidian''), while main entries are all in Hanyu Pinyin order. There is one all-''sijiaohaoma'' small dictionary (Third Revision, below).

===Second Revision===

A minor Second Revision was made during and just after World War II. This was used by most postwar lexicographers including [[Morohashi Tetsuji]], who created his 12-volume Sino-Japanese dictionary, the ''[[Dai Kan-Wa jiten]]'' and included the Four Cornerfour-corner index among several other lookup methods. [[Oshanin]] (USSR) included a Four Cornerfour-corner index in his Chinese-Russian dictionary and in new China, an extraordinary projectedition of the ''25 Histories'' (Ershi wu''Ershiwu shi'') was published in the early 1950s with a Four Cornerfour-corner index volume containing the entire content.

Then, in 1958, with the introduction of [[Pinyin]]pinyin, a small "''Xin Sijiaohaoma Cidian"'' was produced by the Beijing Commercial Press, but the rapid Han character simplification of the following years made the small (30,000 compound) book obsolete in China. Overseas and in Hong Kong, it remained popular for a number of years as a high speed key to phonetic dictionaries and indexes. It was used by those partly literate in Chineseor or—in some areas—unfamiliarunfamiliar with [[Standard Chinese]], especially Hanyu Pinyin.

Wang Yunwu produced a "''Xiao Cidian"'' and "''Zonghe Cidian"'' in the late 1940s.; Inthe Taiwan, "Zonghe Cidian"latter remains in print in Taiwan, with an auxiliary section of rare characters. Theand gives the telecode number, radical and stroke counts are shown for each character in a convenient size, but a phonetic index is still lacking. Also, it's all in [[traditional Chinese characters]], and it contains a lot of obsolete information. Still, it is convenient for reading old [[Republic of China (1912–1949)|Republic]]-period materials and literature, and as a handy finder for pronunciations.

===Third Revision===

During the [[Cultural Revolution]] in mainland China, the Fourfour-Cornercorner Methodmethod underwent a radical Third Revision during the compilation of the experimental volume of the [[Chinese dictionary#Chinese–Chinese dictionaries|''Xiandai Hanyu Cidian'']], Commercial Press, Beijing, 1972. Another medium-sized dictionary, the ''[[Xinhua Zidian]]'', appeared with this index as well, but in the late 1990s the four-corner index disappeared from newer editions. Both works now use only the Pinyinpinyin main entry and multi-door radical index systems that make it possible to look up a character with perhaps a wrong radical (i.e., characters appear redundantly under different radicals) and the number of strokes and variant forms are greatly reduced, and many more people are literate and capable of transcribing Mandarin Chinese with Pinyinpinyin. The use of stroke counting and radicals puts memorization of the character ahead of sheer speed in handling it. This method is more supportive of mass literacy than classical scholarship or processing and filing names or characters for the majority in China today.

The four-corner method is ultimately for readers, researchers, editors and fileclerks, not for writers who seek a character that they know in speech or recitation. In China today, a new version of the excellent small "''Xin Sijiaohaoma Cidian"'', soft cover from Commercial Press, Beijing, has been available since the late 1970s, updated in several new editions and printings. It also uses the Third Revision and enjoys some popularity.

==Current usage==

The main purpose of the original four-corner system today is in doing academic research or handling large numbers of characters, terms, index cards, or names. It is also used in computer entry, where a smaller list of items is created to browse from than with other systems. The ''[[Xinhua Zidian]]'' large type edition is available with a four-corner index for those whose failing eyesight precludes browsing and counting strokes.

In China today, many famous [[Kuomintang|KMT]] period reference books and collections with four-corner indexes are being reprinted for sale to scholars and those interested in Old Chinese language or historical studies.{{Citation needed|date=December 2018}}

==Summary==

{{unreferenced section|date=August 2013}}

The four-corner method, in its three revisions, was supported by the Chinese state for a while, and is found in numerous older reference works and some still in publication. The small Kangorin Sino-Japanese Dictionary by Yoneyama had a four-corner index when it was introduced in the 1980s, but it has been since deleted.

In China today, many famous [[Kuomintang|KMT]] period reference books and collections with four-corner indexes are being reprinted for sale to scholars and those interested in Old Chinese language or historical studies.{{Citation needed|date=December 2018}}

The four-corner method is not in common usage in China or Taiwan today, although dictionaries with it are available in many bookshops and libraries for those who need or desire to learn or use it. It is identified, in public opinion, with the time when many Chinese were illiterate and the language was not yet unified; more Chinese today use the dictionary to help them write, not read. But it is useful for scholars, clerks, editors, compilers, and especially for foreigners who read Chinese. In recent years it has achieved a new usage as a character input system for computers, generating very short lists to browse.

==See also==

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===Uses===

* [[CKC Chinese Input System]], implementation of the four-corner method

* [[Wiktionary:Wiktionary:Chinese four corner index|Chinese four-corner index]], listing of many Chinese characters sorted by Fourfour-Cornercorner number

===Other structural encodings===

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==External links==

*[https://web.archive.org/web/20100206034658/http://www.sungwh.freeserve.co.uk/sapienti/fourcinp.htm Four Corner System for Searching Character Indexes and Computer Input explained]

*[httphttps://www.mdbg.net/chindictchinese/chindict.phpdictionary?page=chardict MDBG online Chinese-English dictionary, a dictionary with four corner code support]

*[http://www.csse.monash.edu.au/~jwb/FOURCORNER.html An overview of the four corner coding system]

*{{cite web |title=Information about Wang Yun-Wu |url=http://blog.kuririnmail.com/wangyunwu |archive-url=https://archive.phtoday/CzLJ20121206014847/http://blog.sanriotown.com/wangyunwu:kuririnmail.com |archive-date=2012-12-606 |date=2009-12-505 |url-status=dead}}

*[https://web.archive.org/web/20100413100909/http://vimimnihongo.googlecodemonash.com/svnedu/vimim/vimimFOURCORNER.html#four-corner VimIM 四角號碼中文輸入法]

*[http://kanji.sljfaq.org/four.html Graphical four-corner lookup] for [[WWWJDIC]].

{{Chinese language}}

{{DEFAULTSORT:Four Cornercorner Methodmethod}}

[[Category:Han characterCJK input methods]]

[[Category:Index (publishing)]]

[[Category:1926 introductions]]