187 research outputs found

    Approximation of subcategories by abelian subcategories

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    Let C\mathcal{C} be an abelian category and let Λ:C→C\Lambda : \mathcal{C}\rightarrow\mathcal{C} be an idempotent functor which is not right exact, so that the zeroth left derived functor L0ΛL_0\Lambda does not necessarily coincide with Λ\Lambda. In this paper we show that, under mild conditions on Λ\Lambda, L0ΛL_0\Lambda is also idempotent, and the category of L0ΛL_0\Lambda-complete objects of C\mathcal{C} is the smallest exact subcategory of C\mathcal{C} containing the Λ\Lambda-complete objects. In the main application, where Λ\Lambda is the II-adic completion functor on a category of modules, this gives us that the category of "LL-complete modules," studied by Greenlees-May and Hovey-Strickland, is not an ad hoc construction but is in fact characterized by a universal property. Generalizations are also given to the case of relative derived functors, in the sense of relative homological algebra

    Generalized Connectives for Multiplicative Linear Logic

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    In this paper we investigate the notion of generalized connective for multiplicative linear logic. We introduce a notion of orthogonality for partitions of a finite set and we study the family of connectives which can be described by two orthogonal sets of partitions. We prove that there is a special class of connectives that can never be decomposed by means of the multiplicative conjunction ? and disjunction ?, providing an infinite family of non-decomposable connectives, called Girard connectives. We show that each Girard connective can be naturally described by a type (a set of partitions equal to its double-orthogonal) and its orthogonal type. In addition, one of these two types is the union of the types associated to a family of MLL-formulas in disjunctive normal form, and these formulas only differ for the cyclic permutations of their atoms

    Homological stability, characteristic classes and the minimal genus problem

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    The purpose of this thesis is to study the (co-)homological properties of the classifying space of subsurface bundles in a trivial background bundle with fiber a manifold M. We will investigate homological stability pheonomena of this moduli space if M is simply-connected and at least 5-dimensional and the subsurfaces are equipped with tangential structures. Additionally we will investigate the representability of second homology classes by surfaces in general topological spaces. In the case of manifolds this yields a measure for the failure of homological stability if M is not simply-connected. In the introduction we will also briefly touch on how to proceed from these homological stability results to determining the stable characteristic classes of subsurface bundles

    Retracts and retractile subcomplexes

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33452/1/0000855.pd

    Ecological study of aquatic midges and some related insects with special reference to feeding habits

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    Die Schweiz ist ein reiches Land. Sie verfĂŒgt ĂŒber viele MillionĂ€re. Der große Reichtum konzentriert sich auf wenige Familien und Personen. In der Schweiz leben aber auch eine halbe Million der Bevölkerung (7,5 Mio.) in Haushalten von ErwerbstĂ€tigen, die weniger als das Existenzminimum verdienen. Über 200‘000 Personen sind auf Sozialhilfe angewiesen. Bei den Vermögen und den verfĂŒgbaren Einkommen hat sich in den letzten Jahren die Kluft zwischen den obersten und untersten zehn Prozent verschĂ€rft. Die Zunahme der sozialen Ungleichheit erhöht die soziale Brisanz, was mehr zu ergrĂŒnden ist. Die soziale Differenzierung dokumentiert Prozesse der Globalisierung. Sie reproduziert und spezifiziert alte soziale Ungleichheiten. Wichtig ist, dass die Soziale Arbeit das thematisiert und weiter theoretisiert

    Ecological study of aquatic midges and some related insects with special reference to feeding habits

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    Published also as thesis (PH.D.) Cornell University, 1916.From Bulletin of the Bureau of Fisheries, vol. XXXVIII, 1921-22.Bibliography: p. 60-61.Mode of access: Internet
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