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How Charles Ehresmann's vision of geometry developed with time

Andrée C. Ehresmann (2007)

Banach Center Publications

In the mid fifties, Charles Ehresmann defined Geometry as "the theory of more or less rich structures, in which algebraic and topological structures are generally intertwined". In 1973 he defined it as the theory of differentiable categories, their actions and their prolongations. Here we explain how he progressively formed this conception, from homogeneous spaces to locally homogeneous spaces, to fibre bundles and foliations, to a general notion of local structures, and to a new foundation of differential...

How to define "convex functions" on differentiable manifolds

Stefan Rolewicz (2009)

Discussiones Mathematicae, Differential Inclusions, Control and Optimization

In the paper a class of families (M) of functions defined on differentiable manifolds M with the following properties: 1 . if M is a linear manifold, then (M) contains convex functions, 2 . (·) is invariant under diffeomorphisms, 3 . each f ∈ (M) is differentiable on a dense G δ -set, is investigated.

Induced differential forms on manifolds of functions

Cornelia Vizman (2011)

Archivum Mathematicum

Differential forms on the Fréchet manifold ( S , M ) of smooth functions on a compact k -dimensional manifold S can be obtained in a natural way from pairs of differential forms on M and S by the hat pairing. Special cases are the transgression map Ω p ( M ) Ω p - k ( ( S , M ) ) (hat pairing with a constant function) and the bar map Ω p ( M ) Ω p ( ( S , M ) ) (hat pairing with a volume form). We develop a hat calculus similar to the tilda calculus for non-linear Grassmannians [6].

Intégrales premières d'une forme de Pfaff analytique

Jean-François Mattei, Robert Moussu (1978)

Annales de l'institut Fourier

Soit ω un germe en 0 C n de 1-forme différentielle holomorphe vérifiant la condition d’intégrabilité ω d ω = 0 . S’il existe un germe h d’application holomorphe de ( C r , 0 ) dans ( C n , 0 ) qui possède les deux propriétés suivantes :a) h * ( ω ) a une intégrale première formelle,b) la codimension du lieu singulier S ( h * ( ω ) ) de h * ( ω ) est supérieure ou égale à 2,alors ω a une intégrale première holomorphe.

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