Positive Subsumption in Fuzzy EL with General t-Norms
نویسندگان
چکیده
The Description Logic EL is used to formulate several large biomedical ontologies. Fuzzy extensions of EL can express the vagueness inherent in many biomedical concepts. We study the reasoning problem of deciding positive subsumption in fuzzy EL with semantics based on general t-norms. We show that the complexity of this problem depends on the specific t-norm chosen. More precisely, if the t-norm has zero divisors, then the problem is co-NP-hard; otherwise, it can be decided in polynomial time. We also show that the best subsumption degree cannot be computed in polynomial time if the t-norm contains the Łukasiewicz t-norm.
منابع مشابه
About Subsumption in Fuzzy EL
Classical Description Logics (DLs) [2] cannot properly deal with the endemic imprecision of biomedical knowledge. For example, the current version of the SNOMEDCT ontology defines a “Perinatal Cyanotic Attack” as a cardiovascular disorder occurring in the perinatal period and manifested through cyanosis. This definition depends on two vague notions, namely the perinatal period—the period of tim...
متن کاملHow Fuzzy Is My Fuzzy Description Logic?
Fuzzy Description Logics (DLs) with t-norm semantics have been studied as a means for representing and reasoning with vague knowledge. Recent work has shown that even fairly inexpressive fuzzy DLs become undecidable for a wide variety of t-norms. We complement those results by providing a class of t-norms and an expressive fuzzy DL for which ontology consistency is linearly reducible to crisp r...
متن کاملPushing the EL Envelope
Recently, it has been shown that the small description logic (DL) EL, which allows for conjunction and existential restrictions, has better algorithmic properties than its counterpart FL0, which allows for conjunction and value restrictions. Whereas the subsumption problem in FL0 becomes already intractable in the presence of acyclic TBoxes, it remains tractable in EL even with general concept ...
متن کاملClassifying Fuzzy Subsumption in Fuzzy-EL+
Fuzzy Description Logics (f-DLs) have been proposed as extensions of classical Description Logics able to handle imprecise and vague knowledge. Although several extensions to expressive DLs have been proposed today and many reasoning algorithms exist there is still no scalable and efficient reasoning system reported, mainly due to inherited computational complexity from crisp DLs and the lack f...
متن کامل