In computability theory and computational complexity theory , RE ( recursively enumerable ) is the class of decision problems for which a 'yes' answer can be verified by a Turing machine in a finite amount of time. Informally, it means that if the answer to a problem instance is 'yes', then there is some procedure that takes finite time to determine this, and this procedure never falsely reports 'yes' when the true answer is 'no'. However, when the true answer is 'no', the procedure is not required to halt; it may go into an " infinite loop " for some 'no' cases. Such a procedure is sometimes called a semi-algorithm , to distinguish it from an algorithm , defined as a complete solution to a decision problem.
15-454: [REDACTED] Look up re or re- in Wiktionary, the free dictionary. Re or RE may refer to: Arts, media and entertainment [ edit ] ...Re (film) , a 2016 Indian Kannada-language film Realencyclopädie der classischen Altertumswissenschaft , a German encyclopedia of classical scholarship Resident Evil ,
30-472: A chemical element Reference pressure (Re), as sound pressure level Reference pressure (Re), in underwater acoustics Computing and mathematics [ edit ] RE (complexity) (recursively enumerable), a complexity class of decision problems Recursively enumerable (r.e.), in computability theory Regular expression , a sequence of characters to match text against a specified pattern Re function, in mathematics, where Re( z ) denotes
45-493: A finite amount of time, but proving membership might take forever. Equivalently, RE is the class of decision problems for which a Turing machine can list all the 'yes' instances, one by one (this is what 'enumerable' means). Each member of RE is a recursively enumerable set and therefore a Diophantine set . To show this is equivalent, note that if there is a machine E {\displaystyle E} that enumerates all accepted inputs, another machine that takes in
60-635: A former Irish regional airline Places [ edit ] Re, Norway , a former municipality in Vestfold county Re, Vestland , a village in Gloppen municipality, Vestland county, Norway Re, Piedmont , an Italian municipality Île de Ré , an island off the west coast of France Le Bois-Plage-en-Ré , a commune on that island Re di Anfo , a torrent (seasonal stream) in Italy Re di Gianico, Re di Niardo, Re di Sellero, and Re di Tredenus, torrents in
75-694: A horror game franchise Music [ edit ] Re, the second syllable of the scale in solfège D (musical note) or Re, the second note of the musical scale in fixed do solfège Re: (band) , a musical duo based in Canada and the US Albums [ edit ] Re (Café Tacuba album) Re (Les Rita Mitsouko album) Re. , by Aya Ueto Re: (EP) , by Kard Language [ edit ] re (interjection) , in Greek Re (kana) (れ and レ), Japanese syllables In re , Latin for 'in
90-610: A preprint announced a proof that RE was equivalent to the class MIP* (the class where a classical verifier interacts with multiple all-powerful quantum provers who share entanglement ); a revised, but not yet fully reviewed, proof was published in Communications of the ACM in November 2021. The proof implies that the Connes embedding problem and Tsirelson's problem are false. RE-complete
105-442: A result. Therefore: Conversely, the set of languages that are neither RE nor co-RE is known as NRNC . These are the set of languages for which neither membership nor non-membership can be proven in a finite amount of time, and contain all other languages that are not in either RE or co-RE . That is: Not only are these problems undecidable, but neither they nor their complement are recursively enumerable. In January of 2020,
120-411: A string can run E {\displaystyle E} and accept if the string is enumerated. Conversely, if a machine M {\displaystyle M} accepts when an input is in a language, another machine can enumerate all strings in the language by interleaving simulations of M {\displaystyle M} on every input and outputting strings that are accepted (there
135-419: Is an order of execution that will eventually get to every execution step because there are countably many ordered pairs of inputs and steps). The set of recursive languages ( R ) is a subset of both RE and co-RE . In fact, it is the intersection of those two classes, because we can decide any problem for which there exists a recogniser and also a co-recogniser by simply interleaving them until one obtains
150-502: Is different from Wikidata All article disambiguation pages All disambiguation pages re">re The requested page title contains unsupported characters : ">". Return to Main Page . RE (complexity) Similarly, co-RE is the set of all languages that are complements of a language in RE . In a sense, co-RE contains languages of which membership can be disproved in
165-554: The Val Camonica , Lombardy, Italy Réunion (ISO 3166-1 code), a French overseas department and island in the Indian Ocean Science and technology [ edit ] Effective reproduction number , in epidemiology Relative effectiveness or RE factor, of an explosive's demolition power Reynolds number ( Re ), a dimensionless quantity in fluid mechanics used to help predict flow patterns Rhenium (symbol Re),
SECTION 10
#1732848140826180-636: The matter of...' RE: and Re:, a standard email subject line prefix Organisations [ edit ] Renew Europe , a political group in the European Parliament Renovación Española , a former Spanish monarchist political party Royal Engineers , a part of the British Army Royal Society of Painter-Printmakers , whose fellows may use the Post-nominal letters RE Stobart Air (former IATA code: RE),
195-631: The real part of a complex number z People [ edit ] Ré (futsal player) , Portuguese futsal player Andrea Re (born 1963), Italian rower Cayetano Ré (1938–2013), Paraguayan footballer Christopher Ré , American computer scientist Davide Re , Italian runner Germán Ré , Argentine footballer Giovanni Battista Re (born 1934), Italian cardinal Maximiliano Ré , Argentine-Italian footballer Paul Ré , American artist and writer Savannah Ré , Canadian singer-songwriter Vincenzo Re , Italian scenic designer Other uses [ edit ] Religious education (RE),
210-492: The same term [REDACTED] This disambiguation page lists articles associated with the title Re . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Re&oldid=1250808682 " Categories : Disambiguation pages Disambiguation pages with surname-holder lists Place name disambiguation pages Hidden categories: Short description
225-563: The study of religion Re (Egyptian religion) , an ancient Egyptian god Regional-Express , a type of regional train in Germany, Luxembourg and Austria See also [ edit ] [REDACTED] Search for "re" on Misplaced Pages. Il re , Italian-language opera Rhee (disambiguation) Ree (disambiguation) All pages with titles beginning with Re All pages with titles containing Re Res (disambiguation) Ra (disambiguation) Topics referred to by
#825174