0000000000940704

AUTHOR

Johannes Ueberberg

showing 2 related works from this author

A characterization of the line set of an odd-dimensional Baer subspace

1990

Generalizing a theorem of Beutelspacher and Seeger, we consider line sets\(\mathcal{L}\) inP=PG(2t + 1,q),t ∈ IN, with the following properties: (1) any (t + 1)-dimensional subspace ofP contains at least one line of\(\mathcal{L}\), (2) if a pointx ofP is incident with at least two lines of\(\mathcal{L}\) then the points in the factor geometryP/x which are induced by the lines of\(\mathcal{L}\) throughx form a blocking set of type (t, 1) inP/x, (3) any line of\(\mathcal{L}\) is coplanar with at least one further line of\(\mathcal{L}\). We will show that the examples of minimal cardinality are exactly the line sets of Baer subspaces ofP.

Set (abstract data type)CombinatoricsDiscrete mathematicsCardinalityBlocking setLine (geometry)Geometry and TopologyCharacterization (mathematics)Type (model theory)Linear subspaceSubspace topologyMathematicsJournal of Geometry
researchProduct

Zur Spektralinvarianz von Algebren von Pseudodifferentialoperatoren in derL p -Theorie

1988

Die Hormander-Klassen Ψ1,δ0 (0≤δ<1) von Pseudodifferentialoperatoren sind Ψ-Algebren. Insbesondere ist die Inverse eines inL(Lp(ℝn)) invertierbaren Pseudodifferentialoperators der Klasse Ψ1,δ0 selbst wieder ein Pseudodifferential-operator derselben Klasse.

Pure mathematicsNumber theoryGeneral MathematicsAlgebraic geometryAlgebra over a fieldMathematicsManuscripta Mathematica
researchProduct