Special linear systems and syzygies
Let be a reduced, equidimensional germ of an analytic singularity with reduced tangent cone . We prove that the absence of exceptional cones is a necessary and sufficient condition for the smooth part of the specialization to the tangent cone to satisfy Whitney’s conditions along the parameter axis . This result is a first step in generalizing to higher dimensions Lê and Teissier’s result for hypersurfaces of which establishes the Whitney equisingularity of and its tangent cone under...
Let be a number field, and suppose is irreducible over . Using algebraic geometry and group theory, we describe conditions under which the -exceptional set of , i.e. the set of for which the specialized polynomial is -reducible, is finite. We give three applications of the methods we develop. First, we show that for any fixed , all but finitely many -specializations of the degree generalized Laguerre polynomial are -irreducible and have Galois group . Second, we study specializations...
The spectrum of the Laplace operator on algebraic and semialgebraic subsets in is studied and the number of small eigenvalues is estimated by the degree of .
The notion of a real semigroup was introduced in [8] to provide a framework for the investigation of the theory of (diagonal) quadratic forms over commutative, unitary, semi-real rings. In this paper we introduce and study an outstanding class of such structures, that we call spectral real semigroups (SRS). Our main results are: (i) The existence of a natural functorial duality between the category of SRSs and that of hereditarily normal spectral spaces; (ii) Characterization of the SRSs as the...