Describing minimal generating sets of toric ideals is a well-studied and difficult problem. Neil White conjectured in 1980 that the toric ideal associated to a matroid is generated by quadrics corresponding to single element symmetric exchanges. We give a combinatorial proof of White’s conjecture for graphic matroids.

Achieving the goals in the title (and others) relies on a cardinality-wise scanning of the ideals of the poset. Specifically, the relevant numbers attached to the k + 1 elment ideals are inferred from the corresponding numbers of the k-element (order) ideals. Crucial in all of this is a compressed representation (using wildcards) of the ideal lattice. The whole scheme invites distributed comput...

Sulfolobus solfataricus and Sulfolobus islandicus contain several genes exhibiting D-arabinose-inducible expression and these systems are ideal for studying mechanisms of archaeal gene expression. At sequence level, only two highly conserved cis elements are present on the promoters: a regulatory element named ara box directing arabinose-inducible expression and the basal promoter element TATA,...

Let A be a semigroup whose only invertible element is 0. For an A-homogeneous ideal we discuss the notions of simple i-syzygies and simple minimal free resolutions of R/I. When I is a lattice ideal, the simple 0-syzygies of R/I are the binomials in I. We show that for an appropriate choice of bases every A-homogeneous minimal free resolution of R/I is simple. We introduce the gcd-complex ∆gcd(b...

The focus of this paper is to outline the experience of a European based software organization utilizing the IDEAL model, while implementing a tailored Capability Maturity Model (CMM) software process improvement program. The goal was to achieve process improvement rather than a specific CMM maturity level. In doing this, the IDEAL model was extensively researched and employed. The benefits and...

In this paper S will denote an AG-groupoid. A two-sided ideal I of S is called a right (left) pure ideal of S , if for each x in I , there is an element y in I such that ) = ( = x yx x xy . A left (right) pure ideal I is called purely prime if it is proper and if for any pure ideals 1 I and 2 I : I I I 2 1 implies I I1 or I I2 . Analogous to the construction of the pure spectrum of a semigroup ...

Multi-element arrays at both ends of a communication link (Multiple Input Multiple Output – MIMO) have the potential of increasing the throughput and/or of improving the link reliability through spatial diversity. In this paper the capability of increasing the throughput in HIPERLAN/2 (H/2) Wireless LAN (WLAN) standard by MIMO Spatial Multiplexing is investigated with both ideal and real channe...

Let K/F denote an abelian extension of number fields with associated rings of integers OK and OF . Let S denote a finite set of places of F containing the archimedean places and those which ramify in K. Assume that S contains at least one place v that splits completely in K and that |S| ≥ 2. For each ideal n ⊂ OF not divisible by a prime that ramifies in K, we denote by σn the associated Froben...

Coupling phenomena between artificial left-handed ~LH! transmission lines are explored on the basis of a transmission line approach of LH materials. A LH forward coupler in the form of an ideal lumped-element ladder network is presented and is shown to exhibit strong forward coupling that increases with decreasing of frequency. A quasi-lumped element microstrip implementation of a LH coupler is...

For any ordered set P, the join dense completions of P form a complete lattice K(P) with least element O(P), the lattice of order ideals of P, and greatest element M(P), the Dedekind-MacNeille completion of P. The lattice K(P) is isomorphic to an ideal of the lattice of all closure operators on the lattice O(P). Thus it inherits some local structural properties which hold in the lattice of clos...