This book presents an elementary introduction to the theory of oriented matroids. The way oriented matroids are introduced 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 with results on polyhedra in R n and show how to restate the essence of the proofs in terms of sign patterns of oriented matroids. 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...