A conjecture of Grünbaum on common transversals.
A Helly number for unions of two boxes in .
A New Step in the Solution of the Szökefalvi-Nagy Problem.
A Proof of Bárány's Theorem
A purely combinatorial proof of the Hadwiger Debrunner conjecture.
A sandwich theorem and Hyers-Ulam stability of affine functions.
A selection theorem of Helly type and its applications
We prove an abstract selection theorem for set-valued mappings with compact convex values in a normed space. Some special cases of this result as well as its applications to separation theory and Hyers-Ulam stability of affine functions are also given.
A simple geometrie proof of a theorem for starshaped unions of convex sets
A staircase illumination theorem for orthogonal polygons.
Bounding the Piercing Number.
Carathéodory's and Helly's dimensions of products of convexity structures
Characterizing certain staircase convex sets in .
Complexity aspects of the Helly property: graphs and hypergraphs.
Determining Dimension of the Kernel of a Cone.
Ein ebenes Transversalenproblem.
Extension of Cm, omega-Smooth Functions by Linear Operators.
Haar spaces and polynomial selections.
Helly property associated with the discrete planes.
Helly-type theorems for infinite and for finite intersections of sets starshaped via staircase paths.
Helly-Type Theorems for Spheres.