This comprehensive text demonstrates how various notions of logic can be viewed as
notions of universal algebra. It is aimed primarily for logisticians in mathematics, philosophy …

Until not too many years ago, all logics except classical logic (and, perhaps, intuitionistic
logic too) were considered to be things esoteric. Today this state of a airs seems to have …

Note carefully that the title of this piece is not 'A Survey of Relevance Logic'. Such a project
would be impossible given the development of the field and even the space limitations of …

The title of this piece is not 'A Survey of Relevance Logic'. Such a project was impossible in
the mid 1980s when the first version of this article was published, due to the development of …

This book is a specialized monograph on interpolation and definability, a notion central in
pure logic and with significant meaning and applicability in all areas where logic is applied …

The existence of simple semantics and appropriate cut-free Gentzen-type formulations are
fundamental intrinsic criteria for the usefulness of logics. In this paper we show that by using …

We provide a general investigation of logic in which the notion of a simple consequence
relation is taken to be fundamental. Our notion is more general than the usual one since we …

Brouwer's views on the foundations of mathematics have inspired the study of intuitionistic
logic, including the study of the intuitionistic propositional calculus and its extensions. The …

CONTENTS: Chapter I. Basic notions and theorems. 1. Sentential languages and their
matrices. 2. Consequence operations. 3. Matrix consequences. 4. The lattice of the set of …

Hypersequent calculi arise by generalizing standard sequent calculi to refer to whole
contexts of sequents instead of single sequents. We present a number of results using …