1,818 research outputs found

    Simply connected projective manifolds in characteristic p>0p>0 have no nontrivial stratified bundles

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    We show that simply connected projective manifolds in characteristic p>0p>0 have no nontrivial stratified bundles. This gives a positive answer to a conjecture by D. Gieseker. The proof uses Hrushovski's theorem on periodic points.Comment: 16 pages. Revised version contains a more general theorem on torsion points on moduli, together with an illustration in rank 2 due to M. Raynaud. Reference added. Last version has some typos corrected. Appears in Invent.math

    Kickshaws

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    A collection of linguistic kickshaws

    Eliashberg's proof of Cerf's theorem

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    Following a line of reasoning suggested by Eliashberg, we prove Cerf's theorem that any diffeomorphism of the 3-sphere extends over the 4-ball. To this end we develop a moduli-theoretic version of Eliashberg's filling-with-holomorphic-discs method.Comment: 32 page

    Measuring the functionality of online stores

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    This paper makes a case for the need of a framework which can be used to measure the functionality delivered by electronic commerce (e-commerce) systems. Such a framework would be helpful in areas such as cost prediction, effort estimatation, and so on. The paper also goes on to propose such a framework, based on the tried and tested methods of function points and object points.peer-reviewe

    Large N 2D Yang-Mills Theory and Topological String Theory

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    We describe a topological string theory which reproduces many aspects of the 1/N expansion of SU(N) Yang-Mills theory in two spacetime dimensions in the zero coupling (A=0) limit. The string theory is a modified version of topological gravity coupled to a topological sigma model with spacetime as target. The derivation of the string theory relies on a new interpretation of Gross and Taylor's ``\Omega^{-1} points.'' We describe how inclusion of the area, coupling of chiral sectors, and Wilson loop expectation values can be incorporated in the topological string approach.Comment: 95 pages, 15 Postscript figures, uses harvmac (Please use the "large" print option.) Extensive revisions of the sections on topological field theory. Added a compact synopsis of topological field theory. Minor typos corrected. References adde
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