Positive Modal Logic is the restriction of the modal local consequence relation defined by the class of all Kripke models to the propositional negation-free modal language. The class of positive modal algebras is the one canonically associated with PML according to the theory of the algebrization of logics [12]. A Priestley-style duality is established between the category of positive modal alg...

Early in my teaching career I became convinced that history has value in causing the student to look at chemistry in a realistic fashion. But, like classroom demonstrations, history should fulfill a teaching objective and not be used merely as entertainment. Further, history is made by human beings and lends a human interest which is lacking when only the facts of chemistry are expounded (1). M...

[1] B. Banaschewski, Über nulldimensionale Räume, Math. Nache 13 (1955) 129-140. [2] F. Borceux and J. Janelidze, Galois Theories, Cambridge University Press (2001). [3] M. Dias and M. Sobral, Descent for Priestley Spaces, Appl. Categor. Struct 14 (2006) 229-241. [4] B. A. Davey and H. A. Priestley, Introduction to Lattices and Order, Cambridge Mathematical Texbooks (1990). [5] R. Engelking and...

We present a new Priestley-style topological duality for bounded N4-lattices, which are the algebraic counterpart of paraconsistent Nelson logic. Our duality differs from the existing one, due to Odintsov, in that we only rely on Esakia duality for Heyting algebras and not on the duality for De Morgan algebras of Cornish and Fowler. A major advantage of our approach is that for our topological ...

Carl Wilhelm Scheele (1742-1786) has an important place in the history of the discovery of respiratory gases because he was undoubtedly the first person to prepare oxygen and describe some of its properties. Despite this, his contributions have often been overshadowed by those of Joseph Priestley and Antoine Lavoisier, who also played critical roles in preparing the gas and understanding its na...

We investigate Heyting varieties determined by prohibition of systems of configuraations in Priestley duals; we characterize the configuration systems yielding such varieties. On the other hand, the question whether a given finitely generated Heyting variety is obtainable by such means is solved for the special case of systems of trees. Priestley duality provides a correspondence between bounde...