Walter Kern

Note on the computational complexity of least core concepts for min-cost spanning tree games

Abstract. Various least core concepts including the classical least core of cooperative games are discussed. By a reduction from minimum cover problems, we prove that computing an element in these least cores is in general NP-hard for minimum cost spanning tree games. As a consequence, computing the nucleolus, the nucleon and the per-capita nucleolus of minimum cost spanning tree games is also NP-hard.

Adjoints of oriented matroids

AbstractAn adjoint of a geometric latticeG is a geometric latticen

Matroid matching in pseudomodular lattices

tilde G

On a problem about covering lines by squares

n of the same rank into which there is an embeddinge mapping the copoints ofG onto the points ofn

An efficient algorithm for solving a special class of LP's

tilde G

On finite locally projective planar spaces

n. In this paper we introduce oriented adjoints and prove that they can be embedded into the extension lattice of oriented matroids.