Let R be a commutative ring with 1 and M left unitary R-module. In this paper, we give generalization for the notions of compressible (retractable) Modules. We study s-essentially (s-essentially retractable). some their advantages, properties, characterizations examples. also relation between retractable modules) classes modules.

We study the automorphism group of the algebraic closure of a substructure A of a pseudo-finite field F . We show that the behavior of this group, even when A is large, depends essentially on the roots of unity in F . For almost all completions of the theory, we show that algebraic closure agrees with definable closure, as soon as A contains the relative algebraic closure of the prime field.

We obtain an explicit representation for quasiradial γ-harmonic functions, which shows that these functions have essentially algebraic nature. In particular, we give a complete description of all γ which admit algebraic quasiradial solutions. Unlike the cases γ = ∞ and γ = 1, only finitely many algebraic solutions is shown to exist for any fixed |γ| > 1. Moreover, there is a special extremal se...

We define collagories essentially as “distributive allegories without zero morphisms”, and show that they are sufficient for accommodating the relation-algebraic approach to graph transformation. Collagories closely correspond to the adhesive categories important for the categorical DPO approach to graph transformation. but thanks to their relation-algebraic flavour provide a more accessible an...

let $k$ be a field of characteristic$p>0$, $k[[x]]$, the ring of formal power series over $ k$,$k((x))$, the quotient field of $ k[[x]]$, and $ k(x)$ the fieldof rational functions over $k$. we shall give somecharacterizations of an algebraic function $fin k((x))$ over $k$.let $l$ be a field of characteristic zero. the power series $finl[[x]]$ is called differentially algebraic, if it satisfies...

We observe that a certain kind of algebraic proof—which covers essentially all known algebraic circuit lower bounds to date—cannot be used to prove lower bounds against VP if and only if what we call succinct hitting sets exist for VP. This is analogous to the Razborov–Rudich natural proofs barrier in Boolean circuit complexity, in that we rule out a large class of lower bound techniques under ...

In this paper we construct a pushforward-pullback adjoint pair for categories of quasi-coherent sheaves, along a morphism of algebraic stacks, which is represented in algebraic stacks over the site C = Affflat. The construction uses the characterization of algebraic stacks of [H3] and is based on the descent description of the category of quasi-coherent sheaves given in [H2]. We show that an es...