Lehman's forbidden minor characterization of ideal 0-1 matrices
An \(m\times n\) (0,1)-matrix is called ideal if the polyhedron \(P(A):= \{x\in \mathbb{R}^ n: Ax\geq e,\;x\geq 0\) (componentwise)\} is nonempty and all of its extreme points are integer-valued, where \(e= (1,\dots,1)^ T\). In 1979 A. Lehman gave characterizations of minimally nonideal (0,1)- matrices which remained unpublished. In the paper under review, the author presents both a documentation of Lehman's investigations and a different proof of the complete characterization of all minimally (almost) nonideal matrices.
scientific article; zbMATH DE number 428336