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On the second order absolute differentiation

Cabras, Antonella, Kolář, Ivan (1999)

Proceedings of the 18th Winter School "Geometry and Physics"

In this paper the authors compare two different approaches to the second order absolute differentiation of a fibered manifold (one of them was studied by the authors [Arch. Math., Brno 33, 23-35 (1997; Zbl 0910.53014)]. The main goal is the extension of one approach to connections on functional bundles of all smooth maps between the fibers of two fibered manifolds over the same base (we refer to the book “Natural Operations in Differential Geometry” [Springer, Berlin (1993; Zbl 0782.53013)] I. Kolar,...

On the simplicial structure of some Weil bundles

Kureš, Miroslav (2000)

Proceedings of the 19th Winter School "Geometry and Physics"

The author considers the problem to give explicit descriptions for several types of bundles on smooth manifolds, naturally related with the bundle of k -dimensional velocities, or k -jets. In fact, this kind of bundles are very natural objects in differential geometry, mechanics and Lagrangian dynamics. For this the author considers Weil bundles that arose from Weil algebras. If a suitable combinatorial data is provided by a simplicial coloured structure, then the author describes the corresponding...

On the structure constants of certain Hecke algebras

Helversen-Pasotto, Anna (1991)

Proceedings of the Winter School "Geometry and Physics"

[For the entire collection see Zbl 0742.00067.]In the first part some general results on Hecke algebras are recalled; the structure constants corresponding to the standard basis are defined; in the following the example of the commuting algebra of the Gelfand- Graev representation of the general linear group G L ( 2 , F ) is examined; here F is a finite field of q elements; the structure constants are explicitly determined first for the standard basis and then for a new basis obtained via a Mellin-transformation....

On the theory of the 4-quasiplanar mappings of almost quaternionic spaces

Mikeš, Josef, Němčíková, Jana, Pokorná, Olga (1998)

Proceedings of the 17th Winter School "Geometry and Physics"

Authors’ abstract: “4-quasiplanar mappings of almost quaternionic spaces with affine connection without torsion are investigated. Geometrically motivated definitions of these mappings are presented. Based an these definitions, fundamental forms of these mappings are found, which are equivalent to the forms of 4-quasiplanar mappings introduced a priori by I. Kurbatova [Sov. Math. 30, 100-104 (1986; Zbl 0602.53029)]”.

On types of non-integrable geometrie

Friedrich, Thomas (2003)

Proceedings of the 22nd Winter School "Geometry and Physics"

A G-structure on a Riemannian manifold is said to be integrable if it is preserved by the Levi-Civita connection. In the presented paper, the following non-integrable G-structures are studied: SO(3)-structures in dimension 5; almost complex structures in dimension 6; G 2 -structures in dimension 7; Spin(7)-structures in dimension 8; Spin(9)-structures in dimension 16 and F 4 -structures in dimension 26. G-structures admitting an affine connection with totally skew-symmetric torsion are characterized....

Peak functions on convex domains

Kolář, Martin (2000)

Proceedings of the 19th Winter School "Geometry and Physics"

Let Ω ⊂ ℂ n be a domain with smooth boundary and p ∈ ∂ Ω . A holomorphic function f on Ω is called a C k ( k = 0 , 1 , 2 , ⋯ ) peak function at p if f ∈ C k ( Ω ¯ ) , f ( p ) = 1 , and | f ( q ) | < 1 for all q ∈ Ω ¯ ∖ { p } . If Ω is strongly pseudoconvex, then C ∞ peak functions exist. On the other hand, J. E. Fornaess constructed an example in ℂ 2 to show that this result fails, even for C 1 functions, on a weakly pseudoconvex domain [Math. Ann. 227, 173-175 (1977; Zbl 0346.32026)]. Subsequently, E. Bedford and J. E. Fornaess showed that there is always a continuous peak function on a...

Pontryagin algebra of a transitive Lie algebroid

Kubarski, Jan (1990)

Proceedings of the Winter School "Geometry and Physics"

[For the entire collection see Zbl 0699.00032.] It was previously known that for every principal fibre bundle P there is some corresponding transitive Lie algebroid A(P) - a vector bundle equipped with some structure like the structure of a Lie algebra in the module of sections. The author of this article shows that the Chern-Weil homomorphism of P is a notion of the Lie algebroid of P, i.e. knowing only A(P) of P one can uniquely reproduce the ring of invariant polynomials ( V g * ) I and the Chern-Weil...

Prolongation of vector fields to jet bundles

Kolář, Ivan, Slovák, Jan (1990)

Proceedings of the Winter School "Geometry and Physics"

[For the entire collection see Zbl 0699.00032.] In this interesting paper the authors show that all natural operators transforming every projectable vector field on a fibered manifold Y into a vector field on its r-th prolongation J r Y are the constant multiples of the flow operator. Then they deduce an analogous result for the natural operators transforming every vector field on a manifold M into a vector field on any bundle of contact elements over M.

Remarks on CR-manifolds of codimension 2 in C 4

Schmalz, Gerd (1999)

Proceedings of the 18th Winter School "Geometry and Physics"

The aim of the article is to give a conceptual understanding of Kontsevich’s construction of the universal element of the cohomology of the coarse moduli space of smooth algebraic curves with given genus and punctures. In a first step the author presents a toy model of tree graphs coloured by an operad 𝒫 for which the graph complex and the universal cycle will be constructed. The universal cycle has coefficients in the operad for Ω ( 𝒫 * ) -algebras with trivial differential over the (dual) cobar construction...

Representations, duals and quantum doubles of monoidal categories

Majid, Shahn (1991)

Proceedings of the Winter School "Geometry and Physics"

[For the entire collection see Zbl 0742.00067.]The Tanaka-Krein type equivalence between Hopf algebras and functored monoidal categories provides the heuristic strategy of this paper. The author introduces the notion of a double cross product of monoidal categories as a generalization of double cross product of Hopf algebras, and explains some of the motivation from physics (the representation theory for double quantum groups).The Hopf algebra constructions are formulated in terms of monoidal categories...

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