<p> Commutative semigroup equations are described, and rules of inference for them are given. Then a skeleton sublattice of the lattice of equational classes of commutative semigroups is described, and a partial description is given of the way in which the rest of the lattice hangs on the skeleton.</p> / Thesis / Doctor of Philosophy (PhD)

No description available.

Titre de l'écran-titre (visionné le 13 décembre 2023) / La théorie des fonctions non commutatives est un domaine de recherche assez nouveau. Elle essaie de généraliser plusieurs résultats déjà connus en analyse complexe en ne supposant pas que les variables indéterminées soient commutatives. Par exemple, les monômes $$X_1X_2 \quad et \quad X_2X_1$$ ne représentent pas la même choses dans ce contexte. Nous verrons d'abord dans les chapitres 1 et 2 comment les fonctions libres, qui sont les fonctions d'intérêt dans la théorie des fonction non commutatives, satisfont des propriétés qui les rendent très régulières et très intéressantes. Dans le chapitre 3, nous verrons comment le théorème de monodromie standard en analyse complexe se généralise a un nouveau théorème encore plus fort dans la théorie des fonctions non commutatives. Dans le chapitre 4, nous étudierons une généralisation de l'espace de Hardy ainsi que l'espace de Drury-Arveson, soit l'espace des fonction $$f(X)=\sum_{\alpha}c_\alpha X^\alpha,$$ où les coefficients sont carré sommables, c'est-à-dire que $$\sum_{\alpha}\left|\alpha \right|^2< \infty.$$ Finalement, dans le chapitre 5, nous verrons comment, sous certaines contraintes, chaque fonction libre est localement représentable par une série entière.

No description available.

This paper presents an introduction to the theory of ideals in a ring with emphasis on ideals in a commutative ring with identity.

The combinatorial objects known as association schemes arise in group theory, extremal graph theory, coding theory, the design of experiments, and even quantum information theory. One may think of a d-class association scheme as a (d + 1)-dimensional matrix algebra over R closed under entrywise products. In this context, an imprimitive scheme is one which admits a subalgebra of block matrices, also closed under the entrywise product. Such systems of imprimitivity provide us with quotient schemes, smaller association schemes which are often easier to understand, providing useful information about the structure of the larger scheme. One important property of any association scheme is that we may find a basis of d + 1 idempotent matrices for our algebra. A cometric scheme is one whose idempotent basis may be ordered E0, E1, . . . , Ed so that there exists polynomials f0, f1, . . . , fd with fi ◦ (E1) = Ei and deg(fi) = i for each i. Imprimitive cometric schemes relate closely to t-distance sets, sets of unit vectors with only t distinct angles, such as equiangular lines and mutually unbiased bases. Throughout this thesis we are primarily interested in three distinct goals: building new examples of cometric association schemes, drawing connections between cometric association schemes and other objects either combinatorial or geometric, and finding new realizability conditions on feasible parameter sets — using these conditions to rule out open parameter sets when possible. After introducing association schemes with relevant terminology and definitions, this thesis focuses on a few recent results regarding cometric schemes with small d. We begin by examining the matrix algebra of any such scheme, first looking for low rank positive semidefinite matrices with few distinct entries and later establishing new conditions on realizable parameter sets. We then focus on certain imprimitive examples of both 3- and 4-class cometric association schemes, generating new examples of the former while building realizability conditions for both. In each case, we examine the related t-distance sets, giving conditions which work towards equivalence; in the case of 3-class Q-antipodal schemes, an equivalence is established. We conclude by partially extending a result of Brouwer and Koolen concerning the connectivity of graphs arising from metric association schemes.

by Ng Siu-Hung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 80-81). / Introduction --- p.iii / Chapter 1 --- Distributive Modules --- p.1 / Chapter 1.1 --- Basic Definitions --- p.1 / Chapter 1.2 --- Distributive modules --- p.3 / Chapter 1.3 --- Direct sum of distributive modules --- p.9 / Chapter 1.4 --- Endomorphisms of a distributive module --- p.13 / Chapter 1.5 --- Distributive modules satisfying chain conditions --- p.20 / Chapter 2 --- Rings with distributive lattices of right ideals --- p.25 / Chapter 2.1 --- Rings of quotients of right D-rings --- p.25 / Chapter 2.2 --- Localization of right D-rings --- p.28 / Chapter 2.3 --- Reduced primary factorizations in right ND-rings --- p.31 / Chapter 2.4 --- ND-rings --- p.38 / Chapter 3 --- Distributive modules over commutative rings --- p.43 / Chapter 3.1 --- Multiplication modules --- p.43 / Chapter 3.2 --- Properties of distributive modules over commutative rings --- p.48 / Chapter 3.3 --- Distributive modules over arithematical rings --- p.52 / Chapter 4 --- Chinese Modules and Universal Chinese rings --- p.59 / Chapter 4.1 --- Introduction --- p.59 / Chapter 4.2 --- Chinese Modules and CRT modules --- p.61 / Chapter 4.3 --- Universal Chinese Rings --- p.65 / Chapter 4.4 --- Chinese modules over Noetherian domains --- p.70 / Chapter 4.5 --- Remarks on CRT modules --- p.77 / Bibliography --- p.80

Putting fractions in lowest terms is a common problem for basic algebra courses, but it is rarely discussed in abstract algebra. In a 1990 paper, D.D. Anderson, D.F. Anderson, and M. Zafrullah published a paper called Factorization in Integral Domains, which summarized the results concerning different factorization properties in domains. In it, they defined an LT domain as one where every fraction is equal to a fraction in lowest terms. That is, for any x/y in the field of fractions of D, there is some a/b with x/y=a/b and the greatest common divisor of a and b is 1. In addition, R. Gilmer included a brief exercise concerning lowest terms over a domain in his book Multiplicative Ideal Theory. In this thesis, we expand upon those definitions. First, in Chapter 2 we make a distinction between putting a fraction in lowest terms and reducing it to lowest terms. In the first case, we simply require the existence of an equal fraction which is in lowest terms, while the second requires an element which divides both the numerator and the denominator to reach lowest terms. We also define essentially unique lowest terms, which requires a fraction to have only one lowest terms representation up to unit multiples. We prove that a reduced lowest terms domain is equivalent to a weak GCD domain, and that a domain which is both a reduced lowest terms domain and a unique lowest terms domain is equivalent to a GCD domain. We also provide an example showing that not every domain is a lowest terms domain as well as an example showing that putting a fraction in lowest terms is a strictly weaker condition than reducing it to lowest terms. Next, in Chapter 3 we discuss how lowest terms in a domain interacts with the polynomial ring. We prove that if D[T] is a unique lowest terms domain, then D must be a GCD domain. We also provide an alternative approach to some of the earlier results using the group of divisibility. So far, all fractions have been representatives of the field of fractions of a domain. However, in Chapter 4 we examine fractions in other localizations of a domain. We define a necessary and sufficient condition on the multiplicatively closed set, and then examine how this relates to existing properties of multiplicatively closed sets. Finally, in Chapter 5 we briefly examine lowest terms in rings with zero divisors. Because many properties of GCDs do not hold in such rings, this proved difficult. However, we were able to prove some results from Chapter 2 in this more general case.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 106-108).

Thesis (Ph. D.)--University of Chicago, Dept. of Mathematics, June 1997. / Includes bibliographical references. Also available on the Internet.