Henry H. Crapo

  • On The Foundations of Combinatorial Theory, Preliminary Edition

    Combinatorial Geometries

    Henry H. Crapo and Gian-Carlo Rota

    It has become clear within the last ten years that combinatorial geometry, together with its order-theoretic counter-part, the geometric lattice, can serve to catalyze the whole field of combinatorial theory, and a major aim of this preliminary edition is to present the theory in a form accessible to mathematicians working in disparate subjects.

    Earlier studies have been one-sided or restricted in their point of view; they were motivated primarily by the desire to extend the classical theory of graphs, or were lattice-theoretic approaches confined to axiomatics and algebraic dependence. These approaches largely ignored the original geometric motivations that gave impetus to the development of combinatorial theory.

    The present work brings all these aspects together in order to emphasize the many-sidedness of combinatorial geometry, and to point up the unifying role it may well play in current developments in combinatorics and its applications.

    The book defines the axiomatics of combinatorial geometry examples, and discusses the notion of a strong map between geometrics. In addition, there is a brief presentation of coordination theory and a sketch of two important lines of future work, the “critical problem” and matching theory. The full chapter titles are given below.

    Contents1. Introduction • 2. Geometries and Geometric Lattices • 3. Six Classical Examples • 4. Span, Bases, Bonds, Dependence, and Circuits • 5. Cryptomorphic Versions of Geometry • 6. Simplicial Geometries • 7. Semimodular Functions • 8. A Glimpse of Matching Theory • 9. Maps • 10. The Extension Theorem • 11. Orthogonality • 12. Factorization of Relatively Complemented Lattices • 13. Factorization of Geometries • 14. Connected Sets • 15. Representation • 16. The Critical Problem • 17. Bibliography

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