NiCr alloys with different components were obtained by pack chromation and homogenization heat treatment of octet Ni lattice. The microstructure, alloy composition, microhardness quasi-static compression properties the lattice tested. results showed that after treatment, had an austenitic structure uniform composition. Compared pure nickel lattice, microhardness, compressive strength, elastic m...

Given a topological space X, K(X) denotes the upper semi-lattice of its (Hausdorff) compactifications. Recent studies have asked when, for αX ∈ K(X), the restriction homomorphism ρ : C(αX) → C(X) is an epimorphism in the category of commutative rings. This article continues this study by examining the sub-semilattice, Kepi(X), of those compactifications where ρ is an epimorphism along with two ...

Symmetric and k-cyclic structure of modal pseudocomplemented De Morgan algebras was introduced previously. In this paper, we first present the construction epimorphisms between finite symmetric (or 2-cyclic) algebras. Furthermore, compute cardinality set all epimorphism structures. Secondly, free on variety display how our computations are in fact generalizations to others literature. Our work ...

Given a graph G = ( V, E ) and threshold ? ? (0, 1], the maximum cardinality quasi- clique problem consists in finding subset C * of vertices V such that density induced by is greater than or equal to ?. This has number applications data mining, e.g ., social networks phone call graphs. We propose matheuristic for solving quasi-clique problem, based on hybridization biased random-key genetic al...

0.1. Related results. Krstić-McCool proved that GL3(A) is not finitely presented if there is an epimorphism from A to F [t] for some field F [Krs-Mc]. Suslin proved that SLn(A[t1, . . . , tk]) is generated by elemetary matrices if n ≥ 3, A is a regular ring, and K1(A) ∼= A× [Su]. GrunewaldMennicke-Vaserstein proved that Sp2n(A[t1, . . . , tk]) is generated by elementary matrices if n ≥ 2 and A ...

let $r$ be a ring and $m$ a right $r$-module with $s=end_r(m)$. a module $m$ is called semi-projective if for any epimorphism $f:mrightarrow n$, where $n$ is a submodule of $m$, and for any homomorphism $g: mrightarrow n$, there exists $h:mrightarrow m$ such that $fh=g$. in this paper, we study sgq-projective and$pi$-semi-projective modules as two generalizations of semi-projective modules. a m...

There is a natural epimorphism from the symmetric algebra to the Rees algebra of an ideal. When this epimorphism is an isomorphism, we say that the ideal is of linear type. Given two determinantal rings over a field, we consider the diagonal ideal, kernel of the multiplication map. We prove in many cases that the diagonal ideal is of linear type and recover the defining ideal of the Rees algebr...

It is proved that in any pointed category with pullbacks, coequalizers and regular epi-mono factorizations, the class of regular epimorphisms is stable under pullback along the so-called balanced effective descent morphisms. Here “balanced” can be omitted if the category is additive. A balanced effective descent morphism is defined as an effective descent morphism p : E → B such that any subobj...