The complexity of existential quantification in concept languages

✍ Scribed by Francesco M. Donini; Maurizio Lenzerini; Daniele Nardi; Bernhard Hollunder; Werner Nutt; Alberto Marchetti Spaccamela

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 965 KB
• Volume: 53
• Category: Article
• ISSN: 0004-3702
• DOI: 10.1016/0004-3702(92)90076-a

✦ Synopsis

Much of the research on concept languages, which also are called terminological languages, has focused on the computational complexity of subsumption. The intractability results can be divided into two groups. First, it has been shown that extending the basic language ,~Sfwith constructs containing some form of logical disjunction leads to co-NP-hard subsumption problems. Secondly, adding negation to ~-makes subsumption PSPACE-complete. The main result of this paper is that extending ,~-with unrestricted existential quantification makes subsumption NP-complete. This is the first proof of intractability for a concept language containing, whether explicitly or implicitly, no construct expressing disjunction. Unrestricted existential quantification is therefore, alongside disjunction, a source of computational complexity in concept languages.