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'''Computer science''' (or '''computing science''') is the study and the [[science]] of various aspects the theoretical foundations of [[computersinformation]]and [[computation]] and their implementation and application in [[computer|computer system]]s. It <ref>"''Computer science is a common source of the study of information''" [http://www.njit.edu/v2/archivecatalog/undergraduate/91/19-und.html Department of Computer and degrees at Information Science], Guttenberg Information Technologies</ref><ref>"''Computer science is the college level study of computation.''" [http://www.csbsju.edu/computerscience/curriculum Computer Science Department, College of Saint Benedict], Saint John's University</ref><ref>"''Computer Science is the study of all aspects of computer systems, from the theoretical foundations to the very practical aspects of managing large software projects.''" [http://study.massey.ac.nz/major.asp?major_code=2010&prog_code=93068 Massey University]</ref> Computer science has many sub-fields; some emphasize the computation of specific results (such as [[computer graphics]]), while others relate to properties of [[computational problem]]s (such as [[computational complexity theory]]). Still others focus on the challenges in implementing computations. For example, [[programming language theory]] studies approaches to describing computations, while [[computer programming]] applies specific [[programming language]]s to solve specific computational problems. A further subfield, [[human-computer interaction]], focuses on the challenges in making computers and beyondcomputations useful, usable and universally accessible to [[humans|people]].

== History =={{main | History of computer science}}The early foundations of what would become computer science predate the invention of the modern [[Categorydigital computer]]. Machines for calculating fixed numerical tasks, such as the [[abacus]], have existed since antiquity. [[Wilhelm Schickard]] built the first mechanical calculator in 1623.<ref>{{cite web|author=Nigel Tout|title=Calculator Timeline|url=http://www.vintagecalculators.com/html/calculator_time-line.html|work=Vintage Calculator Web Museum|year=2006|accessdate=2006-09-18}}</ref> [[Charles Babbage]] designed a [[difference engine]] in [[Victorian era|Victorian]] times (between 1837 and 1901)<ref>{{cite web | url=http://www.sciencemuseum.org.uk/on-line/babbage/index.asp | title=Science Museum - Introduction to Babbage | accessdate=2006-09-24}}</ref> helped by [[Ada Lovelace]].<ref>{{cite web| url=http://www.scottlan.edu/Lriddle/women/ada-love.htm| title=A Selection and Adaptation From Ada's Notes found in "Ada, The Enchantress of Numbers," by Betty Alexandra Toole Ed.D. Strawberry Press, Mill Valley, CA | accessdate=2006-05-04}}</ref> Around 1900, the [[IBM]] corporation sold [[Key punch|punch-card machines]].<ref>{{cite web | url=http://www.pattonhq.com/ibm.html | title=IBM Punch Cards in the U.S. Army | accessdate=2006-09-24}}</ref> However, all of these machines were constrained to perform a single task, or at best some subset of all possible tasks. During the 1940s, as newer and more powerful computing machines were developed, the term ''computer'' came to refer to the machines rather than their human predecessors. As it became clear that computers could be used for more than just mathematical calculations, the field of computer science broadened to study [[computation]] in general. Computer science began to be established as a distinct academic discipline in the 1960s, with the creation of the first computer science departments and degree programs.<ref name="Denning_cs_discipline">{{cite journal | last=Denning | first=P.J. | authorlink=Peter J. Denning | year=2000 | title=Computer Science: The Discipline | url=http://web.archive.org/web/20060525195404/http://www.idi.ntnu.no/emner/dif8916/denning.pdf | journal=Encyclopedia of Computer Science|format=PDF}}</ref> Since practical computers became available, many applications of computing have become distinct areas of study in their own right. Although many initially believed it impossible that computers themselves could actually be a scientific field of study, in the late fifties it gradually became accepted among the greater academic population.<ref name="Levy1984">{{cite book | authorlink = Steven Levy | last = Levy | first = Steven | title = [[Hackers: Heroes of the Computer Revolution]] | year = 1984 | id = ISBN 0-385-19195-2 | publisher = Doubleday }}</ref> It is the now well-known IBM brand that formed part of the computer science revolution during this time. IBM (short for International Business Machines) released the IBM 704 and later the IBM 709 computers, which were widely used during the exploration period of such devices. "Still, working with the IBM [computer] was frustrating...if you had misplaced as much as one letter in one instruction, the program would crash, and you would have to start the whole process over again".<ref name="Levy1984"/> During the late 1950s, the computer science discipline was very much in its developmental stages, and such issues were commonplace. Time has seen significant improvements in the usability and effectiveness of computer science technology. Modern society has seen a significant shift from computers being used solely by experts or professionals to a more widespread user base. == Major achievements == {{Expand-section|date=June 2008}} [[Image:Enigma.jpg|170px|thumbnail|right|[[Germany|German]] military used the [[Enigma machine]] during [[World War II]] for communication they thought to be secret. The large-scale decryption of Enigma traffic at [[Bletchley Park]] was an important factor that contributed to Allied victory in WWII.<ref name="kahnbook" />]] Despite its relatively short history as a formal academic discipline, computer science has made a number of fundamental contributions to [[science]] and [[society]]. These include: ;Applications within computer science * A formal definition of [[computation]] and [[computability]], and proof that there are computationally [[Undecidable problem|unsolvable]] and [[Intractable#Intractability|intractable]] problems.<ref>{{cite paper | author=Constable, R.L. | date=March 2000 | url=http://www.cs.cornell.edu/cis-dean/bgu.pdf | title=Computer Science: Achievements and Challenges circa 2000|format=PDF}}</ref>* The concept of a [[programming language]], a tool for the precise expression of methodological information at various levels of abstraction.<ref>{{cite book|| last=Abelson| first=H.| authorlink=Hal Abelson| coauthors=G.J. Sussman with J.Sussman| year=1996| title=Structure and Interpretation of Computer Programs| edition=2nd Ed.| publisher=MIT Press| id=ISBN 0-262-01153-0| quote=The computer revolution is a revolution in the way we think and in the way we express what we think. The essence of this change is the emergence of what might best be called ''procedural epistemology'' — the study of the structure of knowledge from an imperative point of view, as opposed to the more declarative point of view taken by classical mathematical subjects.}}</ref> ;Applications outside of computing * Sparked the [[Digital Revolution]], which led to the current [[Information Age]] and the [[Internet]].<ref name="bgu">http://www.cis.cornell.edu/Dean/Presentations/Slides/bgu.pdf</ref>* In [[cryptography]], [[Cryptanalysis of the Enigma|breaking the Enigma machine]] was an important factor contributing to the Allied victory in World War II.<ref name="kahnbook">[[David Kahn]], [[The Codebreakers]], 1967, ISBN 0-684-83130-9.</ref>* [[Scientific computing]] enabled advanced study of the mind, and mapping the human genome became possible with [[Human Genome Project]].<ref name="bgu"/> [[Distributed computing]] projects such as [[Folding@home]] explore [[protein folding]].* [[Algorithmic trading]] has increased the [[Economic efficiency|efficiency]] and [[Market liquidity|liquidity]] of financial markets by using [[artificial intelligence]], [[machine learning]], and other [[statistics|statistical]] and [[Numerical analysis|numerical]] techniques on a large scale.<ref>[http://www.telegraph.co.uk/money/main.jhtml?xml=/money/2006/08/27/ccsoft27.xml Black box traders are on the march] The Telegraph, August 26, 2006</ref><br> == Fields of computer science ==As a discipline, computer science spans a range of topics from theoretical studies of algorithms and the limits of computation to the practical issues of implementing computing systems in hardware and software.<ref name="CSAB1997">{{cite web|author=Computing Sciences Accreditation Board|title=Computer Science as a Profession|url=http://www.csab.org/comp_sci_profession.html |date=28 May 1997| accessdate=2008-09-01}}</ref><ref>{{cite book|author=Committee on the Fundamentals of Computer Science: Challenges and Opportunities, National Research Council |title=Computer Science: Reflections on the Field, Reflections from the Field|url=http://www.nap.edu/catalog.php?record_id=11106#toc|publisher=National Academies Press|id=ISBN 978-0-309-09301-9|date=2004}}</ref>The Computer Sciences Accreditation Board (CSAB) – which is made up of representatives of the [[Association for Computing Machinery]] (ACM), the [[Institute of Electrical and Electronics Engineers]] Computer Society, and the [[Association for Information Systems]] – identifies four areas that it considers crucial to the discipline of computer science: ''theory of computation'', ''algorithms and data structures'', ''programming methodology and languages'', and ''computer elements and architecture''. In addition to these four areas, CSAB also identifies fields such as software engineering, artificial intelligence, computer networking and communication, database systems, parallel computation, distributed computation, computer-human interaction, computer graphics, operating systems, and numerical and symbolic computation as being important areas of computer science.<ref name="CSAB1997"/> === Theory of computation ===:{| style="border:1px solid #ddd; text-align:center; margin: auto;" cellspacing="15"| [[Image:Afd exemple.png|96px]]|| [[Image:Wang tiles.png|96px]]|| '''P = NP''' ?|| [[Image:Blochsphere.svg|96px]]|-| [[Automata theory]]|| [[Computability theory (computer science)|Computability theory]]|| [[Computational complexity theory]]|| [[Quantum computer|Quantum computing theory]]|} ==== Mathematical foundations ====:{| style="border:1px solid #ddd; text-align:center; margin: auto;" cellspacing="15"| <math> P \Rightarrow Q \,</math>|| [[Image:Elliptic curve simple.png|96px]]|| [[Image:6n-graf.svg|96px]]|| '''int''' ''x''|| [[Image:Commutative diagram for morphism.svg|96px]]|| [[Image:SimplexRangeSearching.png|96px]]|-| [[Mathematical logic]]|| [[Number theory]]|| [[Graph theory]]|| [[Type Theory]]|| [[Category Theory]]|| [[Computational geometry]]|} === Algorithms and data structures ===:{| style="border:1px solid #ddd; text-align:center; margin: auto;" cellspacing="15"| <math>O(n^2)</math>|| [[Image:Sorting quicksort anim.gif|96px]]|| [[Image:Singly linked list.png|96px]]|-| [[Analysis of algorithms]]|| [[Algorithms]]|| [[Data structures]]|} === Programming methodology and languages ===:{| style="border:1px solid #ddd; text-align:center; margin: auto;" cellspacing="15"| [[Image:Ideal compiler.png|96px]]|| [[Image:Python add5 syntax.svg|96px]]|-| [[Compilers]]|| [[Programming languages]]|} === Computer elements and architecture ===:{| style="border:1px solid #ddd; text-align:center; margin: auto;" cellspacing="15"| [[Image:NOR ANSI.svg|96px]]| [[Image:Fivestagespipeline.png|96px]]| [[Image:SIMD.svg|96px]]|-| [[Digital logic]]| [[Microarchitecture]]| [[Multiprocessing]]|} === Numerical and symbolic computation ===:{| style="border:1px solid #ddd; text-align:center; margin: auto;" cellspacing="15"| [[Image:1u04-argonaute.png|96px]]|| [[Image:User-FastFission-brain.gif|96px]]|| [[Image:Naphthalene-3D-balls.png|96px]]|| [[Image:Neuron-no labels.png|96px]]|| [[Image:X-43A (Hyper - X) Mach 7 computational fluid dynamic (CFD).jpg|96px]]|| [[Image:Wind-particle.png|96px]]|| <math>y = \sin(x) + c</math>|-| [[Bioinformatics]]|| [[Cognitive Science]]|| [[Computational chemistry]]|| [[Computational neuroscience]]|| [[Computational physics]]|| [[Numerical_analysis|Numerical algorithms]]|| [[Symbolic mathematics]]|} == Relationship with other fields ==Despite its name, a significant amount of computer science does not involve the study of computers themselves. Because of this, several alternative names have been proposed. Danish scientist [[Peter Naur]] suggested the term ''datalogy'', to reflect the fact that the scientific discipline revolves around data and data treatment, while not necessarily involving computers. The first scientific institution to use the term was the Department of Datalogy at the University of Copenhagen, founded in 1969, with Peter Naur being the first professor in datalogy. The term is used mainly in the Scandinavian countries. Also, in the early days of computing, a number of terms for the practitioners of the field of computing were suggested in the ''Communications of the ACM'' – ''turingineer'', ''turologist'', ''flow-charts-man'', ''applied meta-mathematician'', and ''applied epistemologist''.<ref>Communications of the ACM 1(4):p.6</ref> Three months later in the same journal, ''comptologist'' was suggested, followed next year by ''hypologist''.<ref>Communications of the ACM 2(1):p.4</ref> The term ''computics'' has also been suggested.<ref>IEEE Computer 28(12):p.136</ref> ''Informatik'' was a term used in Europe with more frequency. The renowned computer scientist [[Edsger W. Dijkstra|Edsger Dijkstra]] stated, "Computer science is no more about computers than astronomy is about telescopes." The design and deployment of computers and computer systems is generally considered the province of disciplines other than computer science. For example, the study of [[computer hardware]] is usually considered part of [[computer engineering]], while the study of commercial [[computer system]]s and their deployment is often called [[information technology]]or [[information systems]]. Computer science is sometimes criticized as being insufficiently scientific, a view espoused in the statement "Science is to computer science as hydrodynamics is to plumbing", credited to [[Stan Kelly-Bootle]]<ref>''Computer Language'', October 1990</ref> and others. However, there has been much cross-fertilization of ideas between the various computer-related disciplines. Computer science research has also often crossed into other disciplines, such as [[cognitive science]], [[economics]], [[mathematics]], [[physics]] (see [[quantum computing]]), and [[linguistics]]. Computer science is considered by some to have a much closer relationship with [[mathematics]] than many scientific disciplines.<ref name="Denning_cs_discipline" /> Early computer science was strongly influenced by the work of mathematicians such as [[Kurt Gödel]] and [[Alan Turing]], and there continues to be a useful interchange of ideas between the two fields in areas such as [[mathematical logic]], [[category theory]], [[domain theory]], and [[algebra]]. The relationship between computer science and [[software engineering]] is a contentious issue, which is further muddied by [[Debates within software engineering|disputes]] over what the term "software engineering" means, and how computer science is defined. [[David Parnas]], taking a cue from the relationship between other engineering and science disciplines, has claimed that the principal focus of computer science is studying the properties of computation in general, while the principal focus of software engineering is the design of specific computations to achieve practical goals, making the two separate but complementary disciplines.<ref>{{cite journal | last = Parnas| first = David L.| authorlink = David Parnas| year = 1998| title = [http://citeseer.ist.psu.edu/parnas98software.html Software Engineering Programmes are not Computer Science Programmes]| journal = Annals of Software Engineering| volume = 6| pages = 19–37| doi = 10.1023/A:1018949113292}}, p. 19: "Rather than treat software engineering as a subfield ofcomputer science, I treat it as an element of the set, {Civil Engineering, Mechanical Engineering,Chemical Engineering, Electrical Engineering, ....}."</ref> The academic, political, and funding aspects of computer science tend to depend on whether a department formed with a mathematical emphasis or with an engineering emphasis. Computer science departments with a mathematics emphasis and with a numerical orientation consider alignment [[computational science]]. Both types of departments tend to make efforts to bridge the field educationally if not across all research. == Computer science education ==Some universities teach computer science as a theoretical study of computation and algorithmic reasoning. These programs often feature the [[theory of computation]], [[analysis of algorithms]], [[formal methods]], [[Concurrency (computer science)|concurrency theory]], [[databases]], [[computer graphics]] and [[systems analysis]], among others. They typically also teach [[computer programming]], but treat it as a vessel for the support of other fields of computer science rather than a central focus of high-level study. Other colleges and universities, as well as [[secondary school]]s and vocational programs that teach computer science, emphasize the practice of advanced [[computer programming]] rather than the theory of algorithms and computation in their computer science curricula. Such curricula tend to focus on those skills that are important to workers entering the software industry. The practical aspects of computer programming are often referred to as [[software engineering]]. However, there is a lot of [[Debates within software engineering|disagreement]] over the meaning of the term, and whether or not it is the same thing as programming. == See also =={{portal}}: ''Main list: [[List of basic computer science topics]]''<div class="references-small" style="-moz-column-count:2; column-count:2;">* [[Career domains in computer science]]* [[Computer scientist]]* [[Computing]]* [[English in computing|English in computer science]]* [[Informatics]]* [[List of academic computer science departments]]* [[List of computer science conferences]]* [[List of computer scientists]]* [[List of important publications in computer science|List of publications in computer science]]* [[List of pioneers in computer science]]* [[List of software engineering topics]]* [[Unsolved problems in computer science|List of open problems in computer science]]* [[Women in computer science]]</div> == References == {{reflist|2}} == Further reading ==* [[Association for Computing Machinery]]. [http://www.acm.org/class/1998/overview.html 1998 ACM Computing Classification System]. 1998.* [[IEEE Computer Society]] and the [[Association for Computing Machinery]]. [http://www.computer.org/portal/cms_docs_ieeecs/ieeecs/education/cc2001/cc2001.pdf Computing Curricula 2001: Computer Science]. December 15, 2001.* [[Peter J. Denning]]. ''[http://portal.acm.org/citation.cfm?id=1053309&coll=&dl=ACM&CFID=15151515&CFTOKEN=6184618 Is computer science science?]'', Communications of the ACM, April 2005.* [[Donald E. Knuth]]. ''Selected Papers on Computer Science,'' CSLI Publications, Cambridge Univ. Press, 1996.* [[Peter J. Denning]], ''[http://portal.acm.org/citation.cfm?id=971303&dl=ACM&coll=&CFID=15151515&CFTOKEN=6184618 Great principles in computing curricula]'', Technical Symposium on Computer Science Education, 2004. == External links =={{wikibooks}}{{wikiversity | Portal:Computer Science}} * {{dmoz|Computers/Computer_Science/}}* [http://www.lecturefox.com/computerscience/ Directory of free university lectures in Computer Science] * [http://liinwww.ira.uka.de/ bibliography/ Collection of Computer Science Bibliographies]* [http://csdir.org/ CS Directory and resources]* [http://se.ethz.ch/~meyer/gallery/ Photographs of computer scientists] ([[Bertrand Meyer]]'s gallery) === Webcasts ===* [http://www.oid.ucla.edu/webcasts/courses/2006-2007/2006fall/cs1 UCLA Computer Science 1 Freshman Computer Science Seminar Section 1]* [http://webcast.berkeley.edu/course_details.php?seriesid=1906978395 Berkeley Introduction to Computers] {{Computer_Science}} <!-- [[sr:Рачунарство]] --> [[Category:Computer science| ]] [[af:Rekenaarwetenskap]][[als:Informatik]][[ar:معلوماتية]][[an:Informatica]][[ast:Informática]][[bn:কম্পিউটার বিজ্ঞান]][[zh-min-nan:Tiān-náu kho-ha̍k]][[bs:Informatika]][[br:Urzhiataerezh]][[bg:Информатика]][[ca:Informàtica]][[cs:Informatika (počítačová věda)]][[da:Datalogi]][[de:Informatik]][[et:Informaatika]][[el:Επιστήμη υπολογιστών]][[es:Ciencias de la computación]][[eo:Komputiko]][[eu:Informatika]][[fa:علوم رایانه]][[fo:Teldufrøði]][[fr:Informatique]][[fy:Ynformatika]][[fur:Informatiche]][[ga:Ríomheolaíocht]][[gv:Sheanse Coearrooagh]][[gl:Informática]][[ko:전산학]][[hr:Računarstvo]][[io:Informatiko]][[id:Ilmu komputer]][[ia:Informatica]][[ie:Informatica]][[iu:ᑐᓴᐅᒪᖃᑦᑕᐅᑎᔾᔪᑎᓂᒃ ᐊᐅᓚᑦᑎᔩᑦ/tusaumaqattautijjutinik aulattijiit]][[is:Tölvunarfræði]][[it:Informatica]][[he:מדעי המחשב]][[csb:Infòrmatika]][[ht:Enfòmatik]][[lad:Informatika]][[la:Informatica]][[lv:Datorzinātne]][[lb:Informatik]][[lt:Kompiuterių mokslas]][[li:Informatica]][[jbo:samske]][[hu:Számítástechnika]][[mk:Информатика]][[mg:Informatika]][[ml:കമ്പ്യൂട്ടര്‍ ശാസ്ത്രം]][[ms:Sains komputer]][[nl:Informatica]][[nds-nl:Infermatika]][[ja:計算機科学]][[no:Informatikk]][[oc:Informatica]][[ug:بیلگیسايار مۈھەندیسلیغی]][[pms:Anformàtica]][[pl:Informatyka]][[pt:Ciência da computação]][[ro:Informatică]][[ru:Информатика]][[sq:Informatika]][[scn:Nfurmàtica]][[simple:Computer science]][[sk:Veda o počítačoch]][[sl:Računalništvo]][[fi:Tietojenkäsittelytiede]][[sv:Datavetenskap]][[tl:Agham pangkompyuter]][[ta:கணினியியல்]][[th:วิทยาการคอมพิวเตอร์]][[vi:Khoa học máy tính]][[tr:Bilgisayar bilimi]][[tk:Informatika]][[uk:Інформатика]][[vec:Computer Science]][[wo:Xibaarfeppal]][[wuu:计算机科学]][[yo:Informatics (Ifitonileti)]][[zh-yue:電算]][[bat-smg:Infuormatėka]][[zh:计算机科学]]