Foundations of knowledge representation and reasoning.- Collective entities and relations in concept languages.- Computing extensions of terminological default theories.- A formalization of interval-based temporal subsumption in first order logic.- Normative, subjunctive and autoepistemic defaults.- Abductive reasoning with abstraction axioms.- Queries, rules and definitions as epistemic sentences in concept languages.- The power of beliefs or translating default logic into standard autoepistemic logic.- Learning an optimally accurate representation system.- Default reasoning via negation as failure.- Weak autoepistemic reasoning and well-founded semantics.- Forming concepts for fast inference.- A common-sense theory of time.- Reasoning with analogical representations.- Asking about possibilities - Revision and update semantics for subjunctive queries Extended report.- On the impact of stratification on the complexity of nonmonotonic reasoning.- Logics of mental attitudes in AI.- Hyperrational conditionals.- Revision by expansion in logic programs.