Editing Description logic (section)

===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.