Let C be a clutter and let I be its edge ideal. We present a combinatorial description of the minimal generators of the symbolic Rees algebra Rs(I) of I . It is shown that the minimal generators of Rs(I) are in one to one correspondence with the irreducible parallelizations of C. From our description some major results on symbolic Rees algebras of perfect graphs and clutters will follow. As a b...

The rings considered in this article are commutative with identity $1neq 0$. By a proper ideal of a ring $R$,  we mean an ideal $I$ of $R$ such that $Ineq R$.  We say that a proper ideal $I$ of a ring $R$ is a  maximal non-prime ideal if $I$ is not a prime ideal of $R$ but any proper ideal $A$ of $R$ with $ Isubseteq A$ and $Ineq A$ is a prime ideal. That is, among all the proper ideals of $R$,...

Let S be a Heegaard splitting surface of a compact orientable 3-manifold M. If S is strongly irreducible, the manner in which it can intersect a ball or a solid torus in M is very constrained and the allowable configurations are simple and useful. Splitting surfaces not conforming to these simple local pictures must be weakly reducible.

Suppose K is a knot in a closed 3-manifold M such that M −N(K) is irreducible. We show that for any integer b there exists a triangulation of M −N(K) such that any weakly incompressible bridge surface for K of b bridges or fewer is isotopic to an almost normal bridge surface.

Nonperturbative approximation schemes are inevitable even in weakly coupled theories if the nonequilibrium behavior of quantum fields is investigated. The two-particle irreducible (2PI) effective action formalism provides an efficient framework for obtaining resummation schemes both in and out of equilibrium. We briefly review the these techniques and discuss recent findings for nonequilibrium ...

SOLVMANIFOLD DARYL COOPER AND MARTIN SCHARLEMANN Abstract. We classify isotopy classes of Heegaard splittings of solvmanifolds. If the monodromy of the solvmanifold can be expressed as m 1 1 0 ; for some m 3 (as always is true when the trace of the monodromy is 3), then any irreducible splitting is strongly irreducible and of genus two. If m 4 any two such splittings are isotopic. If m = 3 then...

Fermionic-type character formulae are presented for charged irreducible modules of the graded parafermionic conformal field theory associated to the coset ôsp(1, 2)k/û(1). This is obtained by counting the weakly ordered ‘partitions’ subject to the graded Z̃k exclusion principle. The bosonic form of the characters is also presented.

It is shown that the discriminant of a discriminant has the same irreducible factors as the product of seven polynomials which are defined as the GCD of the generators of an elimination ideal. Under tame conditions of genericity, three of these polynomials are irreducible and generate the corresponding elimination ideal, while the four other are equal to one. Moreover the factors of two of thes...

It is known that there exists a Minimum Distance Diagram (MDD) for circulant digraphs of degree two (or double-loop computer networks) which is an L-shape. Its description provides the diameter and the average distance of the graph on constant time. In this paper we clarify, justify and extend these diagrams to circulant digraphs of arbitrary degree by presenting monomial ideals as a natural to...

In this paper, new examples of weakly symmetric spaces in the sense of A. Selberg 14] are constructed. Let G be a connected, simply-connected, simple Lie group of hermitian type and K a maximal compactly embedded subgroup of G such that D = G=K is an irreducible classical bounded symmetric domain. Let G 1 and D 1 be circle extensions of G and D, respectively. The factor of automorphy induces a ...