Editing Description logic (section)

==History==
Description logic was given its current name in the 1980s. Previous to this it was called (chronologically): ''terminological systems'', and ''concept languages''.

===Knowledge representation===
[[semantic frames|Frame]]s and [[semantic network]]s lack formal (logic-based) semantics.<ref name="DLHB">Franz Baader, Ian Horrocks, and Ulrike Sattler ''Chapter 3 Description Logics''. In Frank van Harmelen, Vladimir Lifschitz, and Bruce Porter, editors, ''Handbook of Knowledge Representation''. Elsevier, 2007.</ref> DL was first introduced into [[knowledge representation]] (KR) systems to overcome this deficiency.<ref name="DLHB"/>

The first DL-based KR system was [[KL-ONE]] (by [[Ronald J. Brachman]] and Schmolze, 1985). During the '80s other DL-based systems using ''structural subsumption algorithms''<ref name="DLHB"/> were developed including KRYPTON (1983), [[LOOM (ontology)|LOOM]] (1987), BACK (1988), K-REP (1991) and CLASSIC (1991). This approach featured DL with limited expressiveness but relatively efficient (polynomial time) reasoning.<ref name="DLHB"/>

In the early '90s, the introduction of a new ''tableau based algorithm'' paradigm allowed efficient reasoning on more expressive DL.<ref name="DLHB"/> DL-based systems using these algorithms — such as KRIS (1991) — show acceptable reasoning performance on typical inference problems even though the worst case complexity is no longer polynomial.<ref name="DLHB"/>

From the mid '90s, reasoners were created with good practical performance on very expressive DL with high worst case complexity.<ref name="DLHB"/> Examples from this period include FaCT,<ref name="fact">{{Cite book | last1 = Tsarkov | first1 = D. | last2 = Horrocks | first2 = I. | chapter = FaCT++ Description Logic Reasoner: System Description | doi = 10.1007/11814771_26 | chapter-url = http://www.cs.ox.ac.uk/ian.horrocks/Publications/download/2006/TsHo06a.pdf| title = Automated Reasoning | series = Lecture Notes in Computer Science | volume = 4130 | pages = 292–297 | year = 2006 | isbn = 978-3-540-37187-8 | citeseerx = 10.1.1.65.2672 }}</ref> [[RACER system|RACER]] (2001), CEL (2005), and [[KAON|KAON 2]] (2005).

DL reasoners, such as FaCT, FaCT++,<ref name="fact"/> RACER, DLP and Pellet,<ref>{{Cite journal | last1 = Sirin | first1 = E. | last2 = Parsia | first2 = B. | last3 = Grau | first3 = B. C. | last4 = Kalyanpur | first4 = A. | last5 = Katz | first5 = Y. | title = Pellet: A practical OWL-DL reasoner | url = http://pellet.owldl.com/papers/sirin05pellet.pdf | doi = 10.1016/j.websem.2007.03.004 | journal = Web Semantics: Science, Services and Agents on the World Wide Web | volume = 5 | issue = 2 | pages = 51–53 | year = 2007 | s2cid = 101226 | url-status = dead | archive-url = https://web.archive.org/web/20070627202215/http://pellet.owldl.com/papers/sirin05pellet.pdf | archive-date = 2007-06-27 }}</ref> implement the [[method of analytic tableaux]]. KAON2 is implemented by algorithms which reduce a SHIQ(D) knowledge base to a disjunctive [[datalog]] program.

===Semantic web===
The [[DARPA Agent Markup Language]] (DAML) and [[Ontology Inference Layer]] (OIL) [[Ontology Language|ontology languages]] for the [[Semantic Web]] can be viewed as
[[Syntax (logic)|syntactic]] variants of DL.<ref name="HS">Ian Horrocks and Ulrike Sattler ''Ontology Reasoning in the SHOQ(D) Description Logic'', in  ''Proceedings of the Seventeenth International Joint Conference on Artificial Intelligence'', 2001.</ref> In particular, the formal semantics and reasoning in OIL use the <math>\mathcal{SHIQ}</math> DL.<ref>{{Cite journal | last1 = Fensel | first1 = D. | last2 = Van Harmelen | first2 = F. | last3 = Horrocks | first3 = I. | last4 = McGuinness | first4 = D. L. | last5 = Patel-Schneider | first5 = P. F. | title = OIL: An ontology infrastructure for the Semantic Web | doi = 10.1109/5254.920598 | journal = [[IEEE Intelligent Systems]] | volume = 16 | issue = 2 | pages = 38–45 | year = 2001 | citeseerx = 10.1.1.307.9456 }}</ref> The [[DAMLplusOIL|DAML+OIL]] DL was developed as a submission to<ref>Ian Horrocks and Peter F. Patel-Schneider ''The Generation of DAML+OIL''. In ''Proceedings of the 2001 Description Logic Workshop (DL 2001)'', volume 49 of CEUR <http://ceur-ws.org/>, pages 30–35, 2001.</ref>—and formed the starting point of—the [[World Wide Web Consortium]] (W3C) Web Ontology Working Group.<ref>Web Ontology Working Group Charter, 2003</ref> In 2004, the Web Ontology Working Group completed its work by issuing the [[Web Ontology Language|OWL]]<ref>W3C Press Release, 2004</ref> recommendation. The design of OWL is based on the <math>\mathcal{SH}</math> family of DL<ref name="HPH">{{Cite journal | last1 = Horrocks | first1 = I. | author-link1 = Ian Horrocks| last2 = Patel-Schneider | first2 = Peter| last3 = van Harmelen | first3 = Frank| author-link3 = Frank van Harmelen| doi = 10.1016/j.websem.2003.07.001 | url = http://www.comlab.ox.ac.uk/people/ian.horrocks/Publications/download/2003/HoPH03a.pdf| title = From SHIQ and RDF to OWL: The making of a Web Ontology Language | journal = Web Semantics: Science, Services and Agents on the World Wide Web | volume = 1 | pages = 7–26 | year = 2003 | citeseerx = 10.1.1.2.7039 | s2cid = 8277015 }}</ref> with OWL DL and OWL Lite based on <math>\mathcal{SHOIN}^\mathcal{(D)}</math> and <math>\mathcal{SHIF}^\mathcal{(D)}</math> respectively.<ref name="HPH"/>

The W3C OWL Working Group began work in 2007 on a refinement of - and extension to - OWL.<ref>OWL Working Group Charter, 2007</ref> In 2009, this was completed by the issuance of the [[Web Ontology Language|OWL2]] recommendation.<ref name='owl2.primer'>{{cite web |url=http://www.w3.org/TR/2009/REC-owl2-primer-20091027/ |title=OWL 2 Web Ontology Language Primer
|last1=Hitzler |first1=Pascal | author-link1=Pascal Hitzler
|last2=Krötzsch |first2=Markus | author-link2=Markus Krötzsch
|last3=Parsia |first3=Bijan | author-link3=Bijan Parsia
|last4=Patel-Schneider |first4=Peter F.  | author-link4=Peter F. Patel-Schneider
|last5=Rudolph |first5=Sebastian  | author-link5=Sebastian Rudolph
|date=27 October 2009 |work=OWL 2 Web Ontology Language  |publisher=World Wide Wed Consortium |access-date=2010-12-14}}</ref> OWL2 is based on the description logic <math>\mathcal{SROIQ}^\mathcal{(D)}</math>.<ref>{{cite book |title=Foundations of Semantic Web Technologies |author1=Pascal Hitzler | author-link1=Pascal Hitzler|author2=Markus Krötzsch |author3=Sebastian Rudolph |publisher=CRCPress |date=August 25, 2009 |isbn=978-1-4200-9050-5 |url=http://www.semantic-web-book.org}}</ref> Practical experience demonstrated that OWL DL lacked several key features necessary to model complex domains.<ref name="GHMPPS"/>