Some completely positive maps on reduced amalgamated free products of C∗–algebras are constructed, showing that every reduced amalgamated free product of exact C∗–algebras is exact. Consequently, every amalgamated free product of exact discrete groups is exact.

Amalgamated graph transformation allows to define schemes of rules coinciding in common core activities and differing over additional parallel independent activities. Consequently, a rule scheme is specified by a kernel rule and a set of extending multi-rules forming an interaction scheme. Amalgamated transformations have been increasingly used in various modeling contexts. Critical Pair Analys...

The theory of Amalgamated Knowledge' Bases [7] represents a formal logical foundation for heterogeneous databases. In an Amalgamated Knowledge Base, data sources are modeled by generalized annotated logic. Moreover, an Amalgamated Knowledge Base is equipped with a supervisor acting as a mediator for amalgamating knowledge from the local databases. Even if the framework is quite appealing, it do...

Let R be a commutative ring with non-zero identity. In this paper, we introduce the concept of weakly J-ideals as new generalization J-ideals. We call proper ideal I J-ideal if whenever a,b ? 0 ab and J(R), then b I. Many basic properties characterizations are studied. investigate under various contexts constructions such direct products, localizations, homomorphic images. Moreover, number exam...

Based on cosmogenic 10Be and 26Al analyses in 15 individual detrital quartz pebbles (16–21 mm) and cosmogenic 10Be in amalgamated medium sand (0.25–0.50 mm), all collected from the outlet of the upper Gaub River catchment in Namibia, quartz pebbles yield a substantially lower average denudation rate than those yielded by the amalgamated sand sample. 10Be and 26Al concentrations in the 15 indivi...

Introduction. If d is a positive square-free integer let Id be the ring of integers in Q(\Jd). Id is a Euclidean domain if d = 1, 2, 3, 7, 11. The groups PSL2(/d) = Fd over these Euclidean rings have recently been investigated. Methods for generating presentations as well as actual presentations were given in [2], [3] and [8], while these groups were shown to be describable in terms of generali...