The Range of Ultrametrics, Compactness, and Separability
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On X-Normed Spaces and Operator Theory on C 0 Over a Field with A
ON X-NORMED SPACES AND OPERATOR THEORY ON c0 OVER A FIELD WITH A KRULL VALUATION OF ARBITRARY RANK by Angel Barría Comicheo A thesis submitted to the Faculty of Graduate Studies of The University of Manitoba in partial fulfillment of the requirements of the degree of Doctor of Philosophy Department of Mathematics University of Manitoba Winnipeg Copyright c 2018 by Angel Barría Comicheo Abstract Between 2013 and 2015 Aguayo et al. developed an operator theory on the space c0 of null sequences in the complex Levi-Civita field C by defining an inner product on c0 that induces the supremum norm on c0 and then studying compact and self- adjoint operators on c0, thus presenting a striking analogy between c0 over C and the Hilbert space `2 over C. In this thesis, we try to obtain these results in the most general case possible by considering a base field with a Krull valuation taking values in an arbitrary commutative group. This leads to the concept of X-normed spaces, which are spaces with norms taking values in a totally ordered set X not necessarily embedded in R. Two goals are considered in the thesis: (1) to present and contribute to a theory of X-normed spaces, and (2) to develop an operator theory on c0 over a field with a Krull valuation of arbitrary rank. In order to meet the goal (1), a systematic study of valued fields, G-modules and X-normed spaces is conducted in order to satisfy the generality of the settings required. For the goal (2), we identify the major differences between normed spaces over fields of rank 1 and X-normed spaces over fields of higher rank; and we try to find the right conditions for which the techniques employed in the rank-1 case can be used in the higher rank case. -
Synthetic Topology and Constructive Metric Spaces
University of Ljubljana Faculty of Mathematics and Physics Department of Mathematics Davorin Leˇsnik Synthetic Topology and Constructive Metric Spaces Doctoral thesis Advisor: izr. prof. dr. Andrej Bauer arXiv:2104.10399v1 [math.GN] 21 Apr 2021 Ljubljana, 2010 Univerza v Ljubljani Fakulteta za matematiko in fiziko Oddelek za matematiko Davorin Leˇsnik Sintetiˇcna topologija in konstruktivni metriˇcni prostori Doktorska disertacija Mentor: izr. prof. dr. Andrej Bauer Ljubljana, 2010 Abstract The thesis presents the subject of synthetic topology, especially with relation to metric spaces. A model of synthetic topology is a categorical model in which objects possess an intrinsic topology in a suitable sense, and all morphisms are continuous with regard to it. We redefine synthetic topology in order to incorporate closed sets, and several generalizations are made. Real numbers are reconstructed (to suit the new background) as open Dedekind cuts. An extensive theory is developed when metric and intrinsic topology match. In the end the results are examined in four specific models. Math. Subj. Class. (MSC 2010): 03F60, 18C50 Keywords: synthetic, topology, metric spaces, real numbers, constructive Povzetek Disertacija predstavi podroˇcje sintetiˇcne topologije, zlasti njeno povezavo z metriˇcnimi prostori. Model sintetiˇcne topologije je kategoriˇcni model, v katerem objekti posedujejo intrinziˇcno topologijo v ustreznem smislu, glede na katero so vsi morfizmi zvezni. Definicije in izreki sintetiˇcne topologije so posploˇseni, med drugim tako, da vkljuˇcujejo zaprte mnoˇzice. Realna ˇstevila so (zaradi sin- tetiˇcnega ozadja) rekonstruirana kot odprti Dedekindovi rezi. Obˇsirna teorija je razvita, kdaj se metriˇcna in intrinziˇcna topologija ujemata. Na koncu prouˇcimo dobljene rezultate v ˇstirih izbranih modelih. Math. Subj. Class. (MSC 2010): 03F60, 18C50 Kljuˇcne besede: sintetiˇcen, topologija, metriˇcni prostori, realna ˇstevila, konstruktiven 8 Contents Introduction 11 0.1 Acknowledgements ................................. -
A Structure Theorem in Finite Topology
Canad. Math. Bull. Vol. 26 (1), 1983 A STRUCTURE THEOREM IN FINITE TOPOLOGY BY JOHN GINSBURG ABSTRACT. Simple structure theorems or representation theorems make their appearance at a very elementary level in subjects such as algebra, but one infrequently encounters such theorems in elemen tary topology. In this note we offer one such theorem, for finite topological spaces, which involves only the most elementary con cepts: discrete space, indiscrete space, product space and homeomorphism. Our theorem describes the structure of those finite spaces which are homogeneous. In this short note we will establish a simple representation theorem for finite topological spaces which are homogeneous. We recall that a topological space X is said to be homogeneous if for all points x and y of X there is a homeomorphism from X onto itself which maps x to y. For any natural number k we let D(k) and I(k) denote the set {1, 2,..., k} with the discrete topology and the indiscrete topology respectively. As usual, if X and Y are topological spaces then XxY is regarded as a topological space with the product topology, which has as a basis all sets of the form GxH where G is open in X and H is open in Y. If the spaces X and Y are homeomorphic we write X^Y. The number of elements of a set S is denoted by \S\. THEOREM. Let X be a finite topological space. Then X is homogeneous if and only if there exist integers m and n such that X — D(m)x/(n). -
Amplicon Analysis I
Amplicon Analysis I Eduardo Pareja-Tobes, Raquel Tobes Oh no sequences! research group, Era7 Bioinformatics Plaza de Campo Verde, 3, 18001 Granada, Spain September 16, 2019 Abstract Here we present 1. a model for amplicon sequencing 2. a definition of the best assignment of a read to a set of reference sequences 3. strategies and structures for indexing reference sequences and computing the best assign- ments of a set of reads efficiently, based on (ultra)metric spaces and their geometry The models, techniques, and ideas are particularly relevant to scenarios akin to 16S taxonomic profiling, where both the number of reference sequences and the read diversity is considerable. Keywords bioinformatics, NGS, DNA sequencing, DNA sequence analysis, amplicons, ultrametric spaces, in- dexing. Corresponding author Eduardo Pareja-Tobes [email protected] 1 1 Reads, Amplicons, References, Assignments In this section we will define what we understand as reads, amplicons, references, and the best as- signment of a read with respect to a set of references. In our model the reads are a product of the probability distribution for the 4 bases (A, C, G and T) in each position of the sequence. 푛−1 Definition 1.0.1 Read. A read 푅 of length 푛 is a product ∏푖=0 푅푖 of 푛 probability distributions on Σ = {퐴, 푇 , 퐶, 퐺}. We will denote the length of a read as |푅|. The corresponding probability mass function is thus defined on the space Σ푛 of sequences in Σ of 푛−1 푛 length 푛, the domain of 푅. The probability that 푅 assigns to a sequence 푥 = (푥푖)푖=0 ∶ Σ is 푛−1 푅(푥) = ∏ 푅푖(푥푖) 푖=0 Remark 1.0.2. -
Arxiv:1810.03128V2 [Math.MG]
FINITE ULTRAMETRIC BALLS O. DOVGOSHEY Abstract. The necessary and sufficient conditions under which a given family F of subsets of finite set X coincides with the family BX of all balls generated by some ultrametric d on X are found. It is shown that the representing tree of the ultrametric space (BX , dH ) with the Hausdorff distance dH can be obtained from the representing tree TX of ultrametric space (X, d) by adding a leaf to every internal vertex of TX . 1. Introduction. Balls in ultrametric space The main object of research in this paper is the set of all balls in a given finite ultrametric space. The theory of ultrametric spaces is closely connected with various directions of studies in mathematics, physics, linguistics, psychology and computer science. Different prop- erties of ultrametric spaces are described at [3, 7, 11–14, 20,21,28,31– 38,42–46]. The use of trees and tree-like structures gives a natural lan- guage for description of ultrametric spaces. For the relationships between these spaces and the leaves or the ends of certain trees see [1,2,5,8,19,22,23,25–27,38]. In particular, a convenient representa- tion of finite ultrametric spaces (X,d) by monotone canonical trees was found by V. Gurvich and M. Vyalyi [22]. A simple algorithm having a clear geometric interpretation was proposed in [40] for constructing monotone canonical trees. Following [40] we will say that these trees arXiv:1810.03128v2 [math.MG] 23 Mar 2019 are representing trees of spaces (X,d). The present paper can be con- sidered as a development of studies initiated at [22] and continued at [10,16,18,39–41]. -
Path Integrals on Ultrametric Spaces by Alan Blair B.Sc, B.A
I Path Integrals on Ultrametric Spaces by Alan Blair B.Sc, B.A. Hons.) University of Sydney 19885 1989 Submitted to the Department of Mathematics in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology May 1994 1994 Alan Blair. All rights reserved. The author hereby grants to MIT permission to reproduce and to distribute copies of this thesis document in whole or 1n Dart. Signature of, Author. .. A-V . Department of Mat4emati _AprilN. Certified by. ,' Gian-Carlo Rota Professor of Mathematics M.I.T. Thesis Advisor Accepted by . q -. ! .; ".. -. , . 1 - L Scfencp David Vogan Chair DepaTtmental Committee on Graduate Studies iFf.7-7r) t4F7171 AUG 1 994 PATH INTEGRALS ON ULTRAMETRIC SPACES by ALAN BLAIR Submitted to the Department of Mathematics on April 29, 1994 in partial fulfillment of the requirements for the degree of Doctor of Philosophy ABSTRACT A framework for the study of path integrals on ad6lic spaces is developed, and it is shown that a family of path space measures on the localizations of an algebraic number field may, under certain conditions, be combined to form a global path space measure on its ade'le ring. An operator on the field of p-adic numbers analogous to the harmonic oscillator operator is then analyzed, and used to construct an Ornstein-Uhlenbeck type process on the ade'le ring of the rationals. Thesis Advisors: Andrew Lesniewski, Professor of Physics (Harvard) Arthur JaHe, Professor of Mathematics (Harvard) 3 Acknowledgments To my father, who first introduced me to the lofty heights of mathematics, and my mother and brother, who kept me in touch with the real world below. -
MATH 614, Spring 2018 [3Mm] Dynamical Systems and Chaos
MATH 614 Dynamical Systems and Chaos Lecture 7: Symbolic dynamics (continued). Symbolic dynamics Given a finite set A (an alphabet), we denote by ΣA the set of all infinite words over A, i.e., infinite sequences s =(s1s2 ... ), si ∈A. For any finite word w over the alphabet A, that is, w = s1s2 ... sn, si ∈A, we define a cylinder C(w) to be the set of all infinite words s ∈ ΣA that begin with w. The topology on ΣA is defined so that open sets are unions of cylinders. Two infinite words are considered close in this topology if they have a long common beginning. The shift transformation σ : ΣA → ΣA is defined by σ(s0s1s2 ... )=(s1s2 ... ). This transformation is continuous. The study of the shift and related transformations is called symbolic dynamics. Properties of the shift • The shift transformation σ :ΣA → ΣA is continuous. • An infinite word s ∈ ΣA is a periodic point of the shift if and only if s = www... for some finite word w. • An infinite word s ∈ ΣA is an eventually periodic point of the shift if and only if s = uwww... for some finite words u and w. • The shift σ has periodic points of all (prime) periods. Dense sets Definition. Suppose (X , d) is a metric space. We say that a subset E ⊂ X is everywhere dense (or simply dense) in X if for every x ∈ X and ε> 0 there exists y ∈ E such that d(y, x) <ε. More generally, suppose X is a topological space. We say that a subset E ⊂ X is dense in X if E intersects every nonempty open subset of X . -
Finite Preorders and Topological Descent I George Janelidzea;1 , Manuela Sobralb;∗;2 Amathematics Institute of the Georgian Academy of Sciences, 1 M
Journal of Pure and Applied Algebra 175 (2002) 187–205 www.elsevier.com/locate/jpaa Finite preorders and Topological descent I George Janelidzea;1 , Manuela Sobralb;∗;2 aMathematics Institute of the Georgian Academy of Sciences, 1 M. Alexidze Str., 390093 Tbilisi, Georgia bDepartamento de Matematica,Ã Universidade de Coimbra, 3000 Coimbra, Portugal Received 28 December 2000 Communicated by A. Carboni Dedicated to Max Kelly in honour of his 70th birthday Abstract It is shown that the descent constructions of ÿnite preorders provide a simple motivation for those of topological spaces, and new counter-examples to open problems in Topological descent theory are constructed. c 2002 Published by Elsevier Science B.V. MSC: 18B30; 18A20; 18D30; 18A25 0. Introduction Let Top be the category of topological spaces. For a given continuous map p : E → B, it might be possible to describe the category (Top ↓ B) of bundles over B in terms of (Top ↓ E) using the pullback functor p∗ :(Top ↓ B) → (Top ↓ E); (0.1) in which case p is called an e)ective descent morphism. There are various ways to make this precise (see [8,9]); one of them is described in Section 3. ∗ Corresponding author. Dept. de MatemÃatica, Univ. de Coimbra, 3001-454 Coimbra, Portugal. E-mail addresses: [email protected] (G. Janelidze), [email protected] (M. Sobral). 1 This work was pursued while the ÿrst author was visiting the University of Coimbra in October=December 1998 under the support of CMUC=FCT. 2 Partial ÿnancial support by PRAXIS Project PCTEX=P=MAT=46=96 and by CMUC=FCT is gratefully acknowledged. -
University of Cape Town Department of Mathematics and Applied Mathematics Faculty of Science
The copyright of this thesis vests in the author. No quotation from it or information derived from it is to be published without full acknowledgementTown of the source. The thesis is to be used for private study or non- commercial research purposes only. Cape Published by the University ofof Cape Town (UCT) in terms of the non-exclusive license granted to UCT by the author. University University of Cape Town Department of Mathematics and Applied Mathematics Faculty of Science Convexity in quasi-metricTown spaces Cape ofby Olivier Olela Otafudu May 2012 University A thesis presented for the degree of Doctor of Philosophy prepared under the supervision of Professor Hans-Peter Albert KÄunzi. Abstract Over the last ¯fty years much progress has been made in the investigation of the hyperconvex hull of a metric space. In particular, Dress, Espinola, Isbell, Jawhari, Khamsi, Kirk, Misane, Pouzet published several articles concerning hyperconvex metric spaces. The principal aim of this thesis is to investigateTown the existence of an injective hull in the categories of T0-quasi-metric spaces and of T0-ultra-quasi- metric spaces with nonexpansive maps. Here several results obtained by others for the hyperconvex hull of a metric space haveCape been generalized by us in the case of quasi-metric spaces. In particular we haveof obtained some original results for the q-hyperconvex hull of a T0-quasi-metric space; for instance the q-hyperconvex hull of any totally bounded T0-quasi-metric space is joincompact. Also a construction of the ultra-quasi-metrically injective (= u-injective) hull of a T0-ultra-quasi- metric space is provided. -
Basic Functional Analysis Master 1 UPMC MM005
Basic Functional Analysis Master 1 UPMC MM005 Jean-Fran¸coisBabadjian, Didier Smets and Franck Sueur October 18, 2011 2 Contents 1 Topology 5 1.1 Basic definitions . 5 1.1.1 General topology . 5 1.1.2 Metric spaces . 6 1.2 Completeness . 7 1.2.1 Definition . 7 1.2.2 Banach fixed point theorem for contraction mapping . 7 1.2.3 Baire's theorem . 7 1.2.4 Extension of uniformly continuous functions . 8 1.2.5 Banach spaces and algebra . 8 1.3 Compactness . 11 1.4 Separability . 12 2 Spaces of continuous functions 13 2.1 Basic definitions . 13 2.2 Completeness . 13 2.3 Compactness . 14 2.4 Separability . 15 3 Measure theory and Lebesgue integration 19 3.1 Measurable spaces and measurable functions . 19 3.2 Positive measures . 20 3.3 Definition and properties of the Lebesgue integral . 21 3.3.1 Lebesgue integral of non negative measurable functions . 21 3.3.2 Lebesgue integral of real valued measurable functions . 23 3.4 Modes of convergence . 25 3.4.1 Definitions and relationships . 25 3.4.2 Equi-integrability . 27 3.5 Positive Radon measures . 29 3.6 Construction of the Lebesgue measure . 34 4 Lebesgue spaces 39 4.1 First definitions and properties . 39 4.2 Completeness . 41 4.3 Density and separability . 42 4.4 Convolution . 42 4.4.1 Definition and Young's inequality . 43 4.4.2 Mollifier . 44 4.5 A compactness result . 45 5 Continuous linear maps 47 5.1 Space of continuous linear maps . 47 5.2 Uniform boundedness principle{Banach-Steinhaus theorem . -
Hierarchical Overlapping Clustering of Network Data Using Cut Metrics Fernando Gama, Santiago Segarra, and Alejandro Ribeiro
IEEE TRANSACTIONS ON SIGNAL AND INFORMATION PROCESSING OVER NETWORKS (ACCEPTED) 1 Hierarchical Overlapping Clustering of Network Data Using Cut Metrics Fernando Gama, Santiago Segarra, and Alejandro Ribeiro Abstract—A novel method to obtain hierarchical and overlap- degrees that may be present. Hierarchical clustering solves ping clusters from network data – i.e., a set of nodes endowed this issue by providing a collection of partitions, indexed with pairwise dissimilarities – is presented. The introduced by a resolution parameter, that can be set by the user to method is hierarchical in the sense that it outputs a nested collection of groupings of the node set depending on the resolution determine the extent up to which nodes are considered similar or degree of similarity desired, and it is overlapping since it or different [9]. In other words, each partition in the collection allows nodes to belong to more than one group. Our construction reflects a different degree of similarity between the nodes, is rooted on the facts that a hierarchical (non-overlapping) ranging from considering all nodes different, to considering clustering of a network can be equivalently represented by all nodes similar. Examples of hierarchical clustering methods a finite ultrametric space and that a convex combination of ultrametrics results in a cut metric. By applying a hierarchical are UPGMA [10], Ward’s method [11], complete [12] or single (non-overlapping) clustering method to multiple dithered versions linkage [13]. of a given network and then convexly combining the resulting However, hierarchical methods still have a major limitation, ultrametrics, we obtain a cut metric associated to the network namely, that nodes are assigned to one and only one category of interest. -
FINITE TOPOLOGICAL SPACES 1. Introduction: Finite Spaces And
FINITE TOPOLOGICAL SPACES NOTES FOR REU BY J.P. MAY 1. Introduction: finite spaces and partial orders Standard saying: One picture is worth a thousand words. In mathematics: One good definition is worth a thousand calculations. But, to quote a slogan from a T-shirt worn by one of my students: Calculation is the way to the truth. The intuitive notion of a set in which there is a prescribed description of nearness of points is obvious. Formulating the “right” general abstract notion of what a “topology” on a set should be is not. Distance functions lead to metric spaces, which is how we usually think of spaces. Hausdorff came up with a much more abstract and general notion that is now universally accepted. Definition 1.1. A topology on a set X consists of a set U of subsets of X, called the “open sets of X in the topology U ”, with the following properties. (i) ∅ and X are in U . (ii) A finite intersection of sets in U is in U . (iii) An arbitrary union of sets in U is in U . A complement of an open set is called a closed set. The closed sets include ∅ and X and are closed under finite unions and arbitrary intersections. It is very often interesting to see what happens when one takes a standard definition and tweaks it a bit. The following tweaking of the notion of a topology is due to Alexandroff [1], except that he used a different name for the notion. Definition 1.2. A topological space is an A-space if the set U is closed under arbitrary intersections.