1,720,984 research outputs found
DISTRIBUTORS AND THE COMPREHENSIVE FACTORIZATION SYSTEM FOR INTERNAL GROUPOIDS
Full text linkIn this note we prove that distributors between groupoids in a Barr-exact category epsilon form the bicategory of relations relative to the comprehensive factorization system in Gpd(epsilon). The case epsilon = Set is of special interest
A NOTE ON THE CATEGORICAL NOTIONS OF NORMAL SUBOBJECT AND OF EQUIVALENCE CLASS
Full text linkIn a non-pointed category E, a subobject which is normal to an equivalence relation is not necessarily an equivalence class. We elaborate this categorical distinction, with a special attention to the Mal'tsev context. Moreover, we introduce the notion of fibrant equipment, and we use it to establish some conditions ensuring the uniqueness of an equivalence relation to which a given subobject is normal, and to give a description of such a relation
A note on strong protomodularity, actions and quotients
Full text linkIn order to study the problems of extending an action along a quotient of the acted object and along a quotient of the acting object, we investigate some properties of the fibration of points. In fact, we obtain a characterization of protomodular categories among quasi-pointed regular ones, and, in the semi-abelian case, a characterization of strong protomodular categories. Eventually, we return to the initial questions by stating the results in terms of internal action
Discrete and Conservative Factorizations in Fib(B)
Full text linkWe focus on the transfer of some known orthogonal factorization systems from Cat to the 2-category Fib(B) of fibrations over a fixed base category B: the internal version of the comprehensive factorization, and the factorization systems given by (sequence of coidentifiers, discrete morphism) and (sequence of coinverters, conservative morphism) respectively. For the class of fibrewise opfibrations in Fib(B) , the construction of the latter two simplify to a single coidentifier (respectively coinverter) followed by an internal discrete opfibration (resp. fibrewise opfibration in groupoids). We show how these results follow from their analogues in Cat, providing suitable conditions on a 2-category C, that allow the transfer of the construction of coinverters and coidentifiers from C to FibC(B)
RELATIVE IDEALS IN HOMOLOGICAL CATEGORIES WITH AN APPLICATION TO MV-ALGEBRAS
No full textLet A be a homological category and U: B → A be a faithful conservative right adjoint. We introduce the notion of relative ideal with respect to U and show that, under suitable conditions, any object of A can be seen as a relative ideal of some object in B. We then develop a case study: we first prove that the category of hoops is semi-abelian and that the category of MV-algebras is protomodular; then we apply our results to the forgetful functor from the category of MV-algebras to the category of Wajsberg hoops
Bipullbacks of fractions and the snail lemma
Full text linkWe establish conditions giving the existence of bipullbacks in bicategories of fractions. We apply our results to construct a π0-π1 exact sequence associated with a fractor between groupoids internal to a pointed exact categor
Fibered aspects of Yoneda's regular span
Full text linkIn this paper we start by pointing out that Yoneda's notion of a regular span S:X→A×B can be interpreted as a special kind of morphism, that we call fiberwise opfibration, in the 2-category Fib(A). We study the relationship between these notions and those of internal opfibration and two-sided fibration. This fibrational point of view makes it possible to interpret Yoneda's Classification Theorem given in his 1960 paper as the result of a canonical factorization, and to extend it to a non-symmetric situation, where the fibration given by the product projection Pr0:A×B→A is replaced by any split fibration over A. This new setting allows us to transfer Yoneda's theory of extensions to the non-additive analog given by crossed extensions for the cases of groups and other algebraic structures
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
On Pseudofunctors Sending Groups to 2-Groups
Full text linkFor a category B with finite products, we first characterize pseudofunctors from B to Cat whose associated opfibration is Cartesian monoidal. Among those, we then characterize the ones which extend to pseudofunctors from internal groups to 2-groups. IfBis additive, this is the case precisely when the associated opfibration has groupoidal fibres
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