in the present paper, we consider biflatness of certain classes of semigroupalgebras. indeed, we give a necessary condition for a band semigroup algebra to bebiflat and show that this condition is not sufficient. also, for a certain class of inversesemigroups s, we show that the biflatness of ell^{1}(s)^{primeprime} is equivalent to the biprojectivity of ell^{1}(s).

This paper is devoted to the algebraic and combinatorial properties of polytopal semigroup rings defined as follows. Let P be a lattice polytope in R n , i. e. a poly-tope whose vertices have integral coordinates, and K a field. Then one considers the embedding ι : R n → R n+1 , ι(x) = (x, 1), and defines S P to be the semigroup generated by the lattice points in ι(P); the K-algebra K[S P ] is ...

The main purpose of this paper is to establish a relation between universality of certain P-compactifications of a semitopological semigroup and their corresponding enveloping semigroups. In particular, we show that if we take P to be the property that the enveloping semigroup of a compactification of a semitopological semigroup s is left simple, a group, or the trivial singleton semigroup, t...

The number of PL-homeomorphism types of combinatorial manifolds in a fixed dimension with an upper bound on g2 is finite. At the intersection of topological and enumerative combinatorics is the relationship between the f -vector of simplicial complex and its topology. The Euler-Poincaré formula is perhaps the oldest such result. More recently, the complete characterization of all possible f -ve...

self-affine maps were successfully used for edge detection, image segmentation, and contour extraction. they belong to the general category of patch-based methods. particularly, each self-affine map is defined by one pair of patches in the image domain. by minimizing the difference between these patches, the optimal translation vector of the self-affine map is obtained. almost all image process...

The aim of this paper is to classify all monogenic ternary semigroups, up to isomorphism. We divide them to two groups: finite and infinite. We show that every infinite monogenic ternary semigroup is isomorphic to the ternary semigroup O, the odd positive integers with ordinary addition. Then we prove that all finite monogenic ternary semigroups with the same index...

in this paper we describe how the degrees of the irreducible characters of the affine subgroups of the classical groups under consideration can be found inductively. in [4] gow obtained certain character degrees for all of the affine subgroups of the classical groups. we apply the method of fischer to the above groups and, in addition to the character degrees given in [4], we obtain some new ch...

Affine semigroups – discrete analogues of convex polyhedral cones – mark the crossroads of algebraic geometry, commutative algebra and integer programming. They constitute the combinatorial background for the theory of toric varieties, which is their main link to algebraic geometry. Initiated by the work of Demazure [De] and Kempf, Knudsen, Mumford and Saint-Donat [KKMS] in the early 70s, toric...