Freeness in classes without equality

1999 ◽  
Vol 64 (3) ◽  
pp. 1159-1194 ◽  
Author(s):  
Raimon Elgueta
Keyword(s):  
Structural Properties ◽  
Universal Algebra ◽  
Reduction Process ◽  
Point Of View ◽  
Basic Notion ◽  
Algebraic Point ◽  
Generic Problem

AbstractThis paper is a continuation of [27], where we provide the background and the basic tools for studying the structural properties of classes of models over languages without equality. In the context of such languages, it is natural to make distinction between two kinds of classes, the so-called abstruct classes, which correspond to those closed under isomorphic copies in the presence of equality, and the reduced classes, i.e., those obtained by factoring structures by their largest congruences. The generic problem described in [27] is to investigate under what conditions this reduction process does not alter the metatheory of a class.Here we focus our attention on a concrete aspect of this generic problem that we import from universal algebra, namely the existence and description of free models. As in [27], we can find here again the basic notion of protoalgebraicity, which was originally introduced in [7] as the weakest condition to guarantee that the reduction process behaves reasonably well from an algebraic point of view. Our concern, however, takes us to handle a further notion, that of semialgebraicity, which corresponds to the notion of equivalential logic of [18]; semialgebraicity turns out to be the property which ensures that freeness is fully preserved by the reduction process.

scholarly journals CONFLICTS AND FAIR TESTING

2006 ◽  
Vol 17 (04) ◽  
pp. 797-813 ◽  
Author(s):  
ROBI MALIK ◽  
DAVID STREADER ◽  
STEVE REEVES
Keyword(s):  
Discrete Event Systems ◽  
Process Algebra ◽  
Discrete Event ◽  
Denotational Semantics ◽  
Point Of View ◽  
Algebraic Point ◽  
Event Systems ◽  
Common Task ◽  
Testing Theory ◽  
Process Algebraic

This paper studies conflicts from a process-algebraic point of view and shows how they are related to the testing theory of fair testing. Conflicts have been introduced in the context of discrete event systems, where two concurrent systems are said to be in conflict if they can get trapped in a situation where they are waiting or running endlessly, forever unable to complete their common task. In order to analyse complex discrete event systems, conflict-preserving notions of refinement and equivalence are needed. This paper characterises an appropriate refinement, called the conflict preorder, and provides a denotational semantics for it. Its relationship to other known process preorders is explored, and it is shown to generalise the fair testing preorder in process-algebra for reasoning about conflicts in discrete event systems.

scholarly journals Obtaining hollow semi-finished products from copper alloys for electrical applications by screw rolling method

2020 ◽  
pp. 27-38 ◽  
Author(s):  
Yu. V. Gamin ◽  
B. A. Romantsev ◽  
A. N. Pashkov ◽  
P. V. Patrin ◽  
I. A. Bystrov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Copper Alloys ◽  
Reduction Process ◽  
Point Of View ◽  
Wall Thickening ◽  
Relative Reduction ◽  
Outer Diameter ◽  
Screw Rolling ◽  
Front End ◽  
Rolling Method

The article proposes a process for obtaining semi-finished products in the form of pipes made of copper alloys for electrical applications using the screw rolling method. The paper presents the results of experimental piercing and rolling of pipe samples made of Cu–0.75Cr copper alloy billets with a diameter of 45 mm. The 43.5×10.0 mm samples obtained after piercing using a two-roll screw rolling mill had exact geometrical dimensions: outer diameter deviation at the front end was up to 1 %, at the back end – up to 2.4 %; relative variation in wall thickness at the front end was 0.3÷0.5 %, at the rear end – 0.5÷1.0 %. Then pierced pipe samples were rolled using a three-roll radial-shear rolling (RSR) mini mill with a different total degree of reduction – samples were obtained with an outer diameter of 30, 25 and 18 mm. The reduction process was analyzed from the point of view of internal hole stability and deformation. In case of 30 % relative reduction of the outer diameter, rolling without a mandrel is accompanied by wall thickening. In this case, inner diameter deviations are within acceptable limits. The experiments on obtaining samples from the Cu–0.75Cr alloy by screw piercing and reduction in the RSR mill show that this scheme can be implemented in principle in industry. At the same time it is necessary to define more exactly deformation parameters (degree of deformation, choice of reduction scheme) to obtain a quality product. Various options for heat treatment (HT) of the obtained pipe samples and the effect of the HT method on electrical conductivity and hardness are considered. Samples after piercing had a conductivity of 59.3 % IACS. The maximum electrical conductivity of 76.7 % IACS was obtained on samples after quenching from a temperature of 1020 °C and aging at 450 °C for 3 h. The results of the work show the fundamental possibility of obtaining semi-finished products from copper alloys for electrical purposes using the screw rolling method.

scholarly journals Localizability of unicycle mobiles robots: An algebraic point of view

2012 ◽  
Author(s):  
Hugues Sert ◽  
Wilfrid Perruquetti ◽  
Annemarie Kokosy ◽  
Xin Jin ◽  
Jorge Palos
Keyword(s):  
Point Of View ◽  
Algebraic Point

scholarly journals Ups and Downs of Water Photodecolorization by Nanocomposite Polymer Nanofibers

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 250 ◽  
Author(s):  
Shahin Homaeigohar ◽  
Niharika Krishna Botcha ◽  
Eman. S. Zarie ◽  
Mady Elbahri
Keyword(s):  
Structural Properties ◽  
Thermomechanical Properties ◽  
Second Order ◽  
Point Of View ◽  
Order Kinetic ◽  
Dye Molecules ◽  
Nanocomposite Polymer ◽  
Nanocomposite System ◽  
Order Kinetic Model ◽  
Pros And Cons

Given the exponentially expanding water pollution causing water scarcity, there is an urgent need for operative nanotechnological systems that can purify water, with insignificant energy consumption, and rapidly. Here, we introduce a nanocomposite system based on TiO2 nanoparticles (NPs) and PES nanofibers (NFs) that can adsorb and then photodecompose organic water pollutants such as dye molecules. We evaluate pros and cons of this system with respect to its purification efficiency and structural properties that can be impacted by the photocatalytic activity of the nanofillers. While the material is superhydrophilic and able to remove 95% methylene blue (MB) from water via adsorption/photodecomposition, its thermomechanical properties decline upon UV irradiation. However, these properties still remain at the level of the neat NFs. The removal behavior is modeled by the first- and second-order kinetic models from the kinetic point of view. The nanocomposite NFs’ removal behavior complies much better with the second-order kinetic model. Overall, such feedbacks implied that the nanocomposite can be effectively applied for water treatment and the structural properties are still as reliable as those of the neat counterpart.

MAGNETIC GROUP ON THE PSEUDOSPHERE

1992 ◽  
Vol 06 (21) ◽  
pp. 3525-3537 ◽  
Author(s):  
V. BARONE ◽  
V. PENNA ◽  
P. SODANO
Keyword(s):  
Magnetic Field ◽  
Hilbert Space ◽  
Quantum Mechanics ◽  
Constant Magnetic Field ◽  
Coherent States ◽  
Compact Operators ◽  
Point Of View ◽  
Algebraic Point ◽  
Planar Limit ◽  
Discrete Part

The quantum mechanics of a particle moving on a pseudosphere under the action of a constant magnetic field is studied from an algebraic point of view. The magnetic group on the pseudosphere is SU(1, 1). The Hilbert space for the discrete part of the spectrum is investigated. The eigenstates of the non-compact operators (the hyperbolic magnetic translators) are constructed and shown to be expressible as continuous superpositions of coherent states. The planar limit of both the algebra and the eigenstates is analyzed. Some possible applications are briefly outlined.

scholarly journals Connectivity of pseudomanifold graphs from an algebraic point of view

2015 ◽  
Vol 353 (12) ◽  
pp. 1061-1065 ◽  
Author(s):  
Karim A. Adiprasito ◽  
Afshin Goodarzi ◽  
Matteo Varbaro
Keyword(s):  
Point Of View ◽  
Algebraic Point

A lattice of extension rings for a commutative ring

1978 ◽  
Vol 84 (2) ◽  
pp. 225-234 ◽  
Author(s):  
D. Kirby ◽  
M. R. Adranghi
Keyword(s):  
Point Of View ◽  
Local Rings ◽  
Algebraic Point ◽  
Multiple Points ◽  
One Dimensional ◽  
Maximal Ideals ◽  
Blowing Up ◽  
Abstract Case ◽  
Algebroid Curve

The work of this note was motivated in the first place by North-cott's theory of dilatations for one-dimensional local rings (see, for example (4) and (5)). This produces a tree of local rings as in (4) which corresponds, in the abstract case, to the branching sequence of infinitely-near multiple points on an algebroid curve. From the algebraic point of view it seems more natural to characterize such one-dimensional local rings R by means of the set of rings which arise by blowing up all ideals Q which are primary for the maximal ideals M of R. This set of rings forms a lattice (R), ordered by inclusion, each ring S of which is a finite R-module. Moreover the length of the R-module S/R is just the reduction number of the corresponding ideal Q (cf. theorem 1 of Northcott (6)). Thus the lattice (R) provides a finer classification of the rings R than does the set of reduction numbers (cf. Kirby (1)).

scholarly journals Electrochemical Behavior of Quinoxalin-2-one Derivatives at Mercury Electrodes and Its Analytical Use

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Milan Zimpl ◽  
Jana Skopalova ◽  
David Jirovsky ◽  
Petr Bartak ◽  
Tomas Navratil ◽  
...  
Keyword(s):  
Electrochemical Behavior ◽  
Reduction Process ◽  
Differential Pulse ◽  
Point Of View ◽  
Semiquinone Radical ◽  
Mesomeric Effect ◽  
Radical Intermediate ◽  
Mercury Electrodes ◽  
Electron Reduction

Derivatives of quinoxalin-2-one are interesting compounds with potential pharmacological activity. From this point of view, understanding of their electrochemical behavior is of great importance. In the present paper, a mechanism of electrochemical reduction of quinoxalin-2-one derivatives at mercury dropping electrode was proposed. Pyrazine ring was found to be the main electroactive center undergoing a pH-dependent two-electron reduction process. The molecule protonization of nitrogen in the position 4 precedes the electron acceptance forming a semiquinone radical intermediate which is relatively stable in acidic solutions. Its further reduction is manifested by separated current signal. A positive mesomeric effect of the nonprotonized amino group in the position 7 of the derivative III accelerates the semiquinone reduction yielding a single current wave. The suggested reaction mechanism was verified by means of direct current polarography, differential pulse, cyclic and elimination voltammetry, and coulometry with subsequent GC/MS analysis. The understanding of the mechanism was applied in developing of analytical method for the determination of the studied compounds.

scholarly journals On the mechanism of oxidation-reduction potential

1927 ◽  
Vol 101 (707) ◽  
pp. 57-70 ◽  
Keyword(s):  
Reduction Potential ◽  
Reduction Process ◽  
Point Of View ◽  
Biological Oxidation ◽  
Hydrogen Atoms ◽  
Oxidation Processes ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
The Subject ◽  
Mechanism Of Oxidation

The phenomena of oxidation-reduction potential are becoming increasingly important in the study of biological oxidation processes. Unfortunately, however, the application of the results obtained from studies on potential to such processes has been somewhat hindered by the fact that the study of potential phenomena has up to the present been approached from a point of view which differs considerably from that of the more important theories of the mechanism of biological oxidation processes. The conceptions used in the development of the two subjects have been different, and the close connection between the two sets of phenomena has thereby been obscured. For instance, Wieland’s theory, which has played such an important part in the development of the subject of biological oxidation processes, is founded on the conception of activation and transfer of hydrogen atoms, while Mansfield Clark, in his recent important and valuable studies on reduction-potential, makes use of conceptions such as electron activity, transfer of “ electron pairs,” and so on. This absence of “ linking up ” between the two sides of the subject has, in fact, been brought up as an objection to the Wieland view. For instance, Clark (3, 4) claims that the reduction-potential phenomena prove that the oxidation-reduction process consists essentially in the transfer of an electron pair from reductant to oxidant, and not in the transfer of hydrogen as assumed by Wieland. He regards this as a very serious objection to the Wieland theory, although possibly not sufficient entirely to disprove it. It must be pointed out, however, that the fact that the electron transfer hypothesis leads to correct results is no proof of its truth until the alternative hypotheses have been shown to yield incorrect results. In the present communication it is shown that the Wieland view also leads to correct results ; in fact, it is possible to predict the reduction-potential phenomena from the work of Wieland. This at once disposes of one of the main objections to Wieland’s theory and renders it possible to relate the mechanism of oxidation-reduction potential with that of biological oxidation-reduction processes.

scholarly journals LIGHTWEIGHT SLAB CAST OVER PRECAST JOISTS

Vestnik MGSU ◽  
2017 ◽  
pp. 636-641 ◽  
Author(s):  
Aleksandr Aleksandrovich Koyankin
Keyword(s):  
Structural Properties ◽  
Point Of View ◽  
Significant Part ◽  
Sound Insulation ◽  
Light Weight ◽  
Longitudinal Reinforcement ◽  
Limit States ◽  
Numerical Studies ◽  
House Building ◽  
Mass Construction

Precast-monolithic house-building in domestic and world practice is a significant part in the mass construction. We propose a relatively large number of designs of precast-monolithic buildings, as well as its individual elements. Despite this, we cannot say that found the most effective constructive solutions able to satisfy the requirements of consumers (future residents) and builders. On this basis, we developed quite effective, from the point of view of construction and further operation, a constructive solution of light weight precast-monolithic overlap. Some features offered are overlapping: smaller mass, compared with beams of heavy concrete; increased heat and sound insulation properties; optimal use of the structural properties of heavy and light precast monolithic concrete and longitudinal reinforcement, depending on the stage of construction. The author has carried out in this article the results of numerical studies the proposed design of precast-monolithic overlap, confirming its compliance with the requirements of 1st and 2nd group of limit States.

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