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Eduard Nigsch

Publications and source records attributed to Eduard Nigsch.

7 recordsLinked to original sources
arXiv2018

Well-posedness for stochastic scalar conservation laws on Riemannian manifolds

We consider the scalar conservation law with stochastic forcing $$ \partial_t u +\mathrm{div}_g {\mathfrak f}(\mx,u)= Φ(\mx,u) dW, \ \ {\bf x} \in M, \ \ t\geq 0 $$ on a smooth compact Riemannian manifold $(M,g)$ where $W$ is the Wiener process and ${\bf x}\mapsto {\mathfrak f}(\mx,ξ)$ is a vector field on $M$ for each $ξ\in {\bf R}$. We introduce admissibility conditions, derive the kinetic formulation and use it to prove well posedness.

math.AP↗
arXiv2014

Unifying order structures for Colombeau algebras

We define a general notion of set of indices which, using concepts from pre-ordered sets theory, permits to unify the presentation of several Colombeau-type algebras of nonlinear generalized functions. In every set of indices it is possible to generalize Landau's notion of big-O such that its usual properties continue to hold. Using this generalized notion of big-O, these algebras can be formally defined the same way as the special Colombeau algebra. Finally, we examine the scope of this formalism and show its effectiveness by applying it to the proof of the pointwise characterization in Colombeau algebras.

math.FA↗
arXiv2011

Manifold-valued generalized functions in full Colombeau spaces

We introduce the notion of generalized function taking values in a smooth manifold into the setting of full Colombeau algebras. After deriving a number of characterization results we also introduce a corresponding concept of generalized vector bundle homomorphisms and, based on this, provide a definition of tangent map for such generalized functions.

math.FA↗
arXiv2011

Nonlinear tensor distributions on Riemannian manifolds

We construct an algebra of nonlinear generalized tensor fields on manifolds in the sense of J.-F. Colombeau, i.e., containing distributional tensor fields as a linear subspace and smooth tensor fields as a faithful subalgebra. The use of a background connection on the manifold allows for a simplified construction based on the existing scalar theory of full diffeomorphism invariant Colombeau algebras on manifolds, still having a canonical embedding of tensor distributions. In the particular case of the Levi-Civita connection on Riemannian manifolds one obtains that this embedding commutes with pullback along homotheties and Lie derivatives along Killing vector fields only.

math.DG↗