9 citations · 18 across the 6 of their papers we have counts for
6 papers
Modular difference logic is hard
Nikolaj Bjørner, Andreas Blass, Yuri Gurevich +1
In connection with machine arithmetic, we are interested in systems of constraints of the form x + k \leq y + k'. Over integers, the satisfiability problem for such systems is poly…
Two Forms of One Useful Logic: Existential Fixed Point Logic and Liberal Datalog
Andreas Blass, Yuri Gurevich
A natural liberalization of Datalog is used in the Distributed Knowledge Authorization Language (DKAL). We show that the expressive power of this liberal Datalog is that of existen…
One useful logic that defines its own truth
Andreas Blass, Yuri Gurevich
Existential fixed point logic (EFPL) is a natural fit for some applications, and the purpose of this talk is to attract attention to EFPL. The logic is also interesting in its own…
Persistent Queries
Andreas Blass, Yuri Gurevich
We propose a syntax and semantics for interactive abstract state machines to deal with the following situation. A query is issued during a certain step, but the step ends before an…
Generalizing Hartogs' Trichotomy Theorem
David Feldman, Mehmet Orhon, Andreas Blass
A celebrated argument of F. Hartogs (1915) deduces the Axiom of Choice from the hypothesis of comparability for any pair of cardinals. We show how each of a sequence of seemingly m…
Basic Subgroups and Freeness, A Counterexample
Andreas Blass, Saharon Shelah
We construct a non-free but aleph_1-separable, torsion-free abelian group G with a pure free subgroup B such that all subgroups of G disjoint from B are free and such that G/B is d…