Higher multiplicities and almost free divisors and complete intersections
About this Title
Publication: Memoirs of the American Mathematical Society
Publication Year 1996: Volume 123, Number 589
ISBNs: 978-0-8218-0481-0 (print); 978-1-4704-0174-0 (online)
MathSciNet review: 1346928
MSC (1991): Primary 32S30; Secondary 14M10, 32S55
In this book, the author considers a general class of nonisolated hypersurface and complete intersection singularities called “almost free divisors and complete intersections”, which simultaneously extend both the free divisors introduced by K. Saito and the isolated hypersurface and complete intersection singularities. They also include discriminants of mappings, bifurcation sets, and certain types of arrangements of hyperplanes, such as Coxeter arrangements and generic arrangements.
Topological properties of these singularities are studied via a “singular Milnor fibration” which has the same homotopy properties as the Milnor fibration for isolated singularities. The associated “singular Milnor number” can be computed as the length of a determinantal module using a Bezout-type theorem. This allows one to define and compute higher multiplicities along the lines of Teissier's $\mu ^*$-constants.
These are applied to deduce topological properties of singularities in a number of situations including: complements of hyperplane arrangements, various nonisolated complete intersections, nonlinear arrangements of hypersurfaces, functions on discriminants, singularities defined by compositions of functions, and bifurcation sets.
Treats nonisolated and isolated singularities together
Uses the singular Milnor fibration with its simpler homotopy structure as an effective tool
Explicitly computes the singular Milnor number and higher multiplicities using a Bezout-type theorem for modules
Graduate students and research mathematicians interested in local analytic singularities, algebraic geometry, singularity theory, topology of arrangements and their applications.
Table of Contents
- I. Almost free divisors
- II. Linear and nonlinear arrangements
- III. Almost free complete intersections
- IV. Topology of compositions and NonREALizability