Linear Programming Duality An Introduction to Oriented Matroids

This book presents an elementary introduction to the theory of oriented matroids. The way oriented matroids are intro- duced emphasizes that they are the most general - and hence simplest - structures for which linear Programming Duality results can be stated and proved. The main theme of the book is duality. Using Farkas' Lemma as the basis the authors start withre- sults on polyhedra in Rn and show how to restate the essence of the proofs in terms of sign patterns of oriented ma- troids. Most of the standard material in Linear Programming is presented in the setting of real space as well as in the more abstract theory of oriented matroids. This approach clarifies the theory behind Linear Programming and proofs become simpler. The last part of the book deals with the facial structure of polytopes respectively their oriented matroid counterparts. It is an introduction to more advanced topics in oriented matroid theory. Each chapter contains suggestions for furt- herreading and the references provide an overview of the research in this field.

1 Prerequisites.- 7.1 Sets and Relations.- 10.2 Linear Algebra.- 14.3 Topology.- 15.4 Polyhedra.- 2 Linear Duality in Graphs.- 2.1 Some Definitions.- 2.2 FARKAS’ Lemma for Graphs.- 2.3 Subspaces Associated with Graphs.- 2.4 Planar Graphs.- 2.5 Further Reading.- 3 Linear Duality and Optimization.- 3.1 Optimization Problems.- 3.2 Recognizing Optimal Solutions.- 3.3 Further Reading.- 4 The FARKAS Lemma.- 4.1 A first version.- 4.2 Homogenization.- 4.3 Linearization.- 4.4 Delinearization.- 4.5 Dehomogenization.- 4.6 Further Reading.- 5 Oriented Matroids.- 5.1 Sign Vectors.- 5.2 Minors.- 5.3 Oriented Matroids.- 5.4 Abstract Orthogonality.- 5.5 Abstract Elimination Property.- 5.6 Elementary vectors.- 5.7 The Composition Theorem.- 5.8 Elimination Axioms.- 5.9 Approximation Axioms.- 5.10 Proof of FARKAS’ Lemma in OMs.- 5.11 Duality.- 5.12 Further Reading.- 6 Linear Programming Duality.- 6.1 The Dual Program.- 6.2 The Combinatorial Problem.- 6.3 Network Programming.- 6.4 Further Reading.- 7 Basic Facts in Polyhedral Theory.- 7.1 MINKOWSKI’S Theorem.- 7.2 Polarity.- 7.3 Faces of Polyhedral Cones.- 7.4 Faces and Interior Points.- 7.5 The Canonical Map.- 7.6 Lattices.- 7.7 Face Lattices of Polars.- 7.8 General Polyhedra.- 7.9 Further Reading.- 8 The Poset (O, ?).- 8.1 Simplifications.- 8.2 Basic Results.- 8.3 Shellability of Topes.- 8.4 Constructibility of O.- 8.5 Further Reading.- 9 Topological Realizations.- 9.1 Linear Sphere Systems.- 9.2 A Nonlinear OM.- 9.3 Sphere Systems.- 9.4 PL Ball Complexes.- 9.5 Further Reading.