EL with Default Attributes and Overriding

Biomedical ontologies and semantic web policy languages based on description logics (DLs) provide fresh motivations for extending DLs with nonmonotonic inferences - a topic that has attracted a significant amount of attention along the years. Despite this, nonmonotonic inferences are not yet supported by the existing DL engines. One reason is the high computational complexity of the existing decidable fragments of nonmonotonic DLs. In this paper we identify a fragment of circumscribed $\EL^\bot$ that supports attribute inheritance with specificity-based overriding (much like an object-oriented language), and such that reasoning about default attributes is in P.