Article

ON THE HOMOLOGY THEORY OF MODULES

Journal of the Faculty of Science. Section I 01/1954;
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    ABSTRACT: The purpose of this text is to equip the reader with an intuitive but precise understanding of elementary structures of category and topos theory. In order to achieve this goal, we provide a guided tour through category theory, leading to the definition of an elementary (Lawvere–Tierney) topos. Then we turn to the investigation of consequences of this definition. In particular, we analyse in detail the topos Set 2 op , the internal structure of its subobject classifier and its variation over stages. Next we turn to the discussion of the interpretation of a logic and language in topos, viewed as a model of higher order intuitionistic multisort type theory, as well as the geometric perspective on a topos, viewed as a category of set-valued sheaves over base category equipped with a Grothendieck topology. This text is designed as an elementary introduction, written in a self-contained way, with no previous knowledge required.
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    ABSTRACT: This text aims to be a short introduction to some of the basic notions in ordinary and enriched category theory. With reasonable detail but always in a compact fashion, we have brought together in the first part of this paper the definitions and basic properties of such notions as limit and colimit constructions in a category, adjoint functors between categories, equivalences and monads. In the second part we pass on to enriched category theory: it is explained how one can "replace" the category of sets and mappings, which plays a crucial role in ordinary category theory, by a more general symmetric monoidal closed category, and how most results of ordinary category theory can be translated to this more general setting. For a lack of space we had to omit detailed proofs, but instead we have included lots of examples which we hope will be helpful. In any case, the interested reader will find his way to the references, given at the end of the paper.