We prove that in theories without the tree property of the second kind (which include dependent and simple theories) forking and dividing over models are the same, and in fact over any extensionâ€¦ (More)

The kinetic behavior of a neutron transport medium which is irradiated by a burst of fast neutrons has been investigated on the basis of several theoretical models. Expressions have been derived forâ€¦ (More)

We show that the groups AGLn (Q) (for n â‰¥ 2) and PGLn (Q) (for n â‰¥ 3), seen as closed subgroups of SÏ‰, are maximal-closed. Subgroups of the infinite symmetric group SÏ‰ (or more generally, SÎº for anyâ€¦ (More)

Given a centerless group one can embed it into its automorphism group which is again centerless. One can define a tower of groups, G, such that G = Aut(G). The Automorphism tower problem asks whenâ€¦ (More)

In this note we interpret Voevodskyâ€™s Univalence Axiom in the language of (abstract) model categories. We then show that any posetal locally Cartesian closed model category Qt in which the mappingâ€¦ (More)

The main result (already achieved in [11]), is that any group can be represented as an automorphism group of a field. We introduce a new proof, using a simple construction. We also bound the field'sâ€¦ (More)