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Reduction theorem for general connections

Josef Janyška — 2011

Annales Polonici Mathematici

We prove the (first) reduction theorem for general and classical connections, i.e. we prove that any natural operator of a general connection Γ on a fibered manifold and a classical connection Λ on the base manifold can be expressed as a zero order operator of the curvature tensors of Γ and Λ and their appropriate derivatives.

Hidden symmetries of the gravitational contact structure of the classical phase space of general relativistic test particle

Josef Janyška — 2014

Archivum Mathematicum

The phase space of general relativistic test particle is defined as the 1-jet space of motions. A Lorentzian metric defines the canonical contact structure on the odd-dimensional phase space. In the paper we study infinitesimal symmetries of the gravitational contact phase structure which are not generated by spacetime infinitesimal symmetries, i.e. they are hidden symmetries. We prove that Killing multivector fields admit hidden symmetries of the gravitational contact phase structure and we give...

Relations between constants of motion and conserved functions

Josef Janyška — 2015

Archivum Mathematicum

We study relations between functions on the cotangent bundle of a spacetime which are constants of motion for geodesics and functions on the odd-dimensional phase space conserved by the Reeb vector fields of geometrical structures generated by the metric and an electromagnetic field.

Remarks on local Lie algebras of pairs of functions

Josef Janyška — 2018

Czechoslovak Mathematical Journal

Starting by the famous paper by Kirillov, local Lie algebras of functions over smooth manifolds were studied very intensively by mathematicians and physicists. In the present paper we study local Lie algebras of pairs of functions which generate infinitesimal symmetries of almost-cosymplectic-contact structures of odd dimensional manifolds.

On Lie algebras of generators of infinitesimal symmetries of almost-cosymplectic-contact structures

Josef Janyška — 2016

Archivum Mathematicum

We study Lie algebras of generators of infinitesimal symmetries of almost-cosymplectic-contact structures of odd dimensional manifolds. The almost-cosymplectic-contact structure admits on the sheaf of pairs of 1-forms and functions the structure of a Lie algebra. We describe Lie subalgebras in this Lie algebra given by pairs generating infinitesimal symmetries of basic tensor fields given by the almost-cosymplectic-contact structure.

Natural vector fields and 2-vector fields on the tangent bundle of a pseudo-Riemannian manifold

Josef Janyška — 2001

Archivum Mathematicum

Let M be a differentiable manifold with a pseudo-Riemannian metric g and a linear symmetric connection K . We classify all natural (in the sense of [KMS]) 0-order vector fields and 2-vector fields on T M generated by g and K . We get that all natural vector fields are of the form E ( u ) = α ( h ( u ) ) u H + β ( h ( u ) ) u V , where u V is the vertical lift of u T x M , u H is the horizontal lift of u with respect to K , h ( u ) = 1 / 2 g ( u , u ) and α , β are smooth real functions defined on R . All natural 2-vector fields are of the form Λ ( u ) = γ 1 ( h ( u ) ) Λ ( g , K ) + γ 2 ( h ( u ) ) u H u V , where γ 1 , γ 2 are smooth real functions defined...

Combinatorial differential geometry and ideal Bianchi–Ricci identities II – the torsion case

Josef JanyškaMartin Markl — 2012

Archivum Mathematicum

This paper is a continuation of [2], dealing with a general, not-necessarily torsion-free, connection. It characterizes all possible systems of generators for vector-field valued operators that depend naturally on a set of vector fields and a linear connection, describes the size of the space of such operators and proves the existence of an ‘ideal’ basis consisting of operators with given leading terms which satisfy the (generalized) Bianchi–Ricci identities without corrections.

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