Degree

Doctor of Philosophy (PhD)

Department

Mathematics

Document Type

Dissertation

Abstract

Targets are matroids that arise from a nested sequence of flats in a projective geometry. This class of matroids was introduced by Nelson and Nomoto, who found the forbidden induced restrictions for binary targets. In this dissertation, their result is generalized to targets arising from projective geometries over $GF(q)$. In addition, targets arising from nested sequences of affine flats are introduced and the forbidden induced restrictions for these affine targets are determined.

In 1963, Halin and Jung proved that every simple graph with minimum degree at least four has $K_5$ or $K_{2,2,2}$ as a minor. Mills and Turner proved an analog of this theorem by showing that every $3$-connected binary matroid in which every cocircuit has size at least four has $F_7, M^*(K_{3,3}), M(K_5),$ or $ M(K_{2,2,2})$ as a minor. Generalizing we prove that every simple matroid in which all cocircuits have at least four elements has as a minor one of nine matroids, seven of which are well known. All nine of these special matroids have rank at most five and have at most twelve elements.

Date

3-19-2026

Committee Chair

James Oxley

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

Download

Share

COinS