We study the Chv\'atal rank of polytopes as a complexity measure of
unsatisfiable sets of clauses. Our first result establishes a
connection between the Chv\'atal rank and the minimum refutation
length in the cutting planes proof system. The result implies that
length lower bounds for cutting planes, or even for ... more >>>

We use recent results on the hardness of resource-bounded
Kolmogorov random strings, to prove that RP is small in SUBEXP
else ZPP=PSPACE and NP=EXP.
We also prove that if NP is not small in SUBEXP, then
NP=AM, improving a former result which held for the measure ... more >>>

A theory, in this context, is a Boolean formula; it is
used to classify instances, or truth assignments. Theories
can model real-world phenomena, and can do so more or less
correctly.
The theory revision, or concept revision, problem is to
correct a given, roughly correct concept.
This problem is ... more >>>