We give alternative proofs of results due to Paris and Wilkie concerning the existence of end extensions of countable models of $B\Sigma_{1}$, that is, the theory of $\Sigma_{1}$ collection.

In June 2012, the conference Trends in Logic XI, whose main theme was Advances in Philosophical Logic, took place at the Ruhr University in Bochum. Eight of the invited papers were published in a special issue of the journal Studia Logica. The present volume contains fourteen papers, which the editors selected out of the contributed papers presented at the conference, in order to offer a panorama of the themes developed in philosophical logic in the last two decades or so, as (...) well as to indicate some promising directions for further research. In what follows, we give a brief description of each contribution, following the order in the list of contents.In the first paper, B. Armour-Garb and J.A. Woodbridge discuss a manner in which one can treat semantic pathologies, such as the Liar Paradox. According to their approach, semantically pathological sentences are s-defective, i.e. they can be understood in a sense, but they bear no content, which we can accept or reject. The a .. (shrink)

On the basis of recent work concerning the meaning of the term stoicheion in Aristotle’s Analytics, we strengthen the view that this treatise can be viewed as a precursor of Euclid’s Elements.

The volume under review contains work dedicated to the memory of Leo Esakia, who died in 2010, after having worked for over 40 years towards developing duality theory for modal and intuitionistic logics. The collection comprises ten technical contributions that follow the first chapter, in which the reader can find information on Esakia’s studies and career, as well as a complete list of his research publications. In the sequel, we will refer briefly to each of these ten chapters, following the (...) order in the list of contents.B. Jónsson and A. Tarski, in two papers they published in the early 1950s in the American Journal of Mathematics, initiated the study of duality for Boolean algebras with additional operations, via the theory of canonical extensions. Esakia was among the first researchers who studied duality for lattices with additional operations [Topological Kripke models. Soviet Math.Dokl. 15 , 147–151], in particular for Heyting algebras and S4 modal algebras. M. Gehrke, a .. (shrink)