Mathematics
http://hdl.handle.net/10125/2093
Tue, 28 Feb 2017 05:36:37 GMT2017-02-28T05:36:37ZLinear and non-linear operators, and the distribution of zeros of entire functions
http://hdl.handle.net/10125/100655
Abstract: An important chapter in the theory of distribution of zeros of entire functions pertains to the study of linear operators acting on entire functions. This dissertation presents new results involving not only linear, but also some non-linear operators.
If fkg1k =0 is a sequence of real numbers, and Q = fqk(x)g1k=0 is a sequence of polynomials, where deg qk(x)= k, associate with the sequence fkg1k =0 a linear operator T such that T[qk(x)]=kqk(x), k = 0; 1; 2; : : : . The sequence fkg1k =0 is termed a Q-multiplier sequence if T is a hyperbolicity preserving operator. Some multiplier sequences are characterized when the polynomial set Q is the set of Jacobi polynomials. In a related question, a family of second order differential operators which preserve hyperbolicity is established. It is shown that a real entire function '(x), expressed in terms of Laguerre-type inequalities, do not require the a priori assumptions about the order and type of '(x) to belong to the Laguerre-P olya class. Recently, P. Br and en proved a conjecture due to S. Fisk, P. R. W. McNamara, B. E. Sagan and R. P. Stanley. The result of P. Br and en is extended, and a related question posed by S. Fisk regarding the distribution of zeros of polynomials under the action of certain non-linear operators is answered.
Description: Ph.D. University of Hawaii at Manoa 2013.; Includes bibliographical references.Thu, 01 Aug 2013 00:00:00 GMThttp://hdl.handle.net/10125/1006552013-08-01T00:00:00ZYoshida, RintaroGeometric optimal control with an application to imaging in nuclear magnetic resonance
http://hdl.handle.net/10125/100723
Abstract: This work addresses the contrast problem in nuclear magnetic resonance as a Mayer problem in optimal control. This is a problem motivated by improving the visible contrast in magnetic resonance imaging, in which the magnetization of the nuclei of the substances imaged are first prepared by being set to a particular configuration by an external magnetic field, the control. In particular we examine the contrast problem by saturation, wherein the magnetization of the first substance is set to zero. This system is modeled by a pair of Bloch equations representing the evolution of the magnetization vectors of the nuclei of two different substances, both influenced by the same control field.
The Pontryagin maximum principle is used to reduce the problem to the analysis of so-called singular trajectories of the system, and we apply the tools of geometric optimal control. We explore the exceptional singular trajectories in detail. In this case the singular control, which is generically a feedback of the state and adjoint vectors of the Hamiltonian system, is a feedback of only the state for this problem, characterizing exceptional singular trajectories as solutions of an ordinary differential equation in the state variables.
We introduce the concept of feedback equivalent control systems and results concerning quadratic differential equations, and compute a set of invariants for the quadratic approximation of exceptional singular ow to distinguish the different cases occurring in physical experiments. Additionally, Grobner bases are employed to make an algebraic-geometric classification of the equilibrium and singular points of the exceptional dynamics.
Description: Ph.D. University of Hawaii at Manoa 2013.; Includes bibliographical references.Sun, 01 Dec 2013 00:00:00 GMThttp://hdl.handle.net/10125/1007232013-12-01T00:00:00ZMarriott, JohnNon-linear coefficient-wise stability and hyperbolicity preserving transformations
http://hdl.handle.net/10125/100958
Abstract: We study the operation of replacing the coeffcients of a real function with a non-linear combination of its coeffcients. We are particularly interested in the coeffcient-wise transformations that preserve the location of zeros in a prescribed region. The earliest example of such transformations may be traced back to the classical composition theorem of Malo, Schur, and Szego, from which it follows that squaring all the coeffcients of a real entire function with only real zeros preserves the reality of zeros. A next and quite recent example of such transformations is due to P. Branden who studied the operation that subtracts from the square of a coeffcient the product of its two closest neighbors. We relate this form of coeffcient-wise transformation to a system of inequalities characterizing the Laguerre-Polya class of real entire functions. Then using Branden's criterion for stability preserving coeffcient-wise transformations we describe a class of non-linear transformations that arise naturally from this system of inequalities. Other systems of inequalities characterizing the Laguerre-Polya class would potentially yield coeffcient-wise transformations of a different character. We investigate the stability preserving properties of coeffcient-wise transformations that arise from the systems of inequalities characterizing the Laguerre-Polya class.
Applications to logarithmic concavity and decreasing sequences yield novel results on the stability preserving properties of these transformations. Under certain conditions the stability-preserving properties of the coeffcient-wise transformations under consideration extend to sequences of real stable polynomials. We highlight several open problems and propose conjectures regarding the stability-preserving properties of transformations considered in this work.
Description: Ph.D. University of Hawaii at Manoa 2012.; Includes bibliographical references.Wed, 01 Aug 2012 00:00:00 GMThttp://hdl.handle.net/10125/1009582012-08-01T00:00:00ZGrabarek, LukaszComplexity of index sets of computable lattices
http://hdl.handle.net/10125/100392
Abstract: We analyze computable algebras in the sense of universal algebra and the index set complexity of properties of such algebras. We look at the difficulty of determining properties of Con(A), the congruence lattice of an algebra A. In particular, we introduce the notion of a class of algebras witnessing the complexity of a property of algebras and show that computable lattices witness the 02-completeness of being simple, as well as witnessing the 03-completeness of having finitely many congruences. Finally, in our main result, we show that the property "to be subdirectly irreducible" is 03-complete as well, and in the process show that computable lattices witness this.
Description: Ph.D. University of Hawaii at Manoa 2014.; Includes bibliographical references.Fri, 01 Aug 2014 00:00:00 GMThttp://hdl.handle.net/10125/1003922014-08-01T00:00:00ZNguyen, Paul Kim Long VuHyperbolicity preserving differential operators and classifications of orthogonal multiplier sequences
http://hdl.handle.net/10125/101054
Abstract: It is well known that every linear operator, T : R[x] ! R[x], can be represented in the form, T := 1Xk=0 Qk(x)Dk; D := d dx ; where fQk(x)g1k=0 is a sequence of real polynomials. An outstanding open problem in the theory of distribution of zeros of polynomials is to characterize the sequence, fQk(x)g1k =0, such that the operator T is hyperbolicity preserving; i.e., T maps polynomials with only real zeros to polynomials of the same kind.
A large portion of this dissertation focuses on diagonal differential operators; that is, T[Bn(x)] := 1Xk=0 Qk(x)Dk!Bn(x) = nBn(x); n 2 N0; where fBn(x)g1n=0 is a simple sequence of real polynomial eigenvectors and f ng1n=0 is the corresponding sequence of real eigenvalues. Our analysis leads to new relations between the eigenvector sequence and the eigenvalue sequence in a diagonal differential operator. In particular, we develop new methods for determining the polynomial coefficients, fQk(x)g1k=0, in cases of Hermite, Laguerre, or monomial linear transformations.
We establish a new representation of linear operators and demonstrate novel hyperbolicity properties for this representation. We show that every Hermite or Laguerre multiplier sequence can be expressed as a sum of classical multiplier sequences.
Using the Malo-Schur-Szeg}o Composition Theorem, we present a new proof of J. Borcea and P. Brändén's seminal result on the hyperbolicity preservation of finite order differential operators. The hyperbolicity preservation of order two differential operators is studied in minute detail; this leads to a new Turán-Wronskian inequality. In addition, a new algebraic characterization is given for the class of Hermite multiplier sequences. Moreover, we prove that in the case of a Hermite diagonal differential operator, T, the zeros of Qk(x) and Qk+1(x) are interlacing, k 0. We generalize several results of D. Bleecker, G. Csordas, T.
Forgács, and A. Piotrowski, partially answer a number of general open problems of T. Craven, G. Csordas, and S. Fisk, and solve a question of M. Chasse. This dissertation concludes with an outline of possible future research and a list of open questions.
Description: Ph.D. University of Hawaii at Manoa 2014.; Includes bibliographical references.Mon, 01 Dec 2014 00:00:00 GMThttp://hdl.handle.net/10125/1010542014-12-01T00:00:00ZBates, Robert D.Congruence Lattices of Finite Algebras
http://hdl.handle.net/10125/25938
Abstract: An important and long-standing open problem in universal algebra asks whether every finite lattice
is isomorphic to the congruence lattice of a finite algebra. Until this problem is resolved, our
understanding of finite algebras is incomplete, since, given an arbitrary finite algebra, we cannot say
whether there are any restrictions on the shape of its congruence lattice. If we find a finite lattice
that does not occur as the congruence lattice of a finite algebra (as many suspect we will), then we
can finally declare that such restrictions do exist.
By a well known result of Palfy and Pudlak, the problem would be solved if we could prove
the existence of a finite lattice that is not the congruence lattice of a transitive group action or,
equivalently, is not an interval in the lattice of subgroups of a finite group. Thus the problem of
characterizing congruence lattices of finite algebras is closely related to the problem of characterizing
intervals in subgroup lattices.
In this work, we review a number of methods for finding a finite algebra with a given congruence
lattice, including searching for intervals in subgroup lattices. We also consider methods for proving
that algebras with a given congruence lattice exist without actually constructing them. By combining
these well known methods with a new method we have developed, and with much help from computer
software like the UACalc and GAP, we prove that with one possible exception every lattice with at
most seven elements is isomorphic to the congruence lattice of a finite algebra. As such, we have
identified the unique smallest lattice for which there is no known representation. We examine this
exceptional lattice in detail, and prove results that characterize the class of algebras that could
possibly represent this lattice.
We conclude with what we feel are the most interesting open questions surrounding this problem
and discuss possibilities for future work.
Description: Thesis (Ph. D.)--University of Hawaii at Manoa, 2012.Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/10125/259382012-01-01T00:00:00ZDeMeo, William J.Sparse ordinary graphs
http://hdl.handle.net/10125/25937
Abstract: Ordinary graphs are directed graphs that can be viewed as generalizations of symmetric block designs. They were introduced by Fossorier, Jezek, Nation and Pogel in [2] in an attempt to construct new finite projective planes. In this thesis we investigate some special cases of ordinary graphs, most prominently the case where nonadjacent vertices have no common neighbors. We determine all connected graphs of this type that exist.
Description: vii, 65 leaves, bound ; 29 cm.; Thesis (Ph. D.)--University of Hawaii at Manoa, 2005.Sat, 01 Jan 2005 00:00:00 GMThttp://hdl.handle.net/10125/259372005-01-01T00:00:00ZKalk, Jonathan W.Small lattices
http://hdl.handle.net/10125/25936
Abstract: This dissertation introduces triple gluing lattices and proves that a triple gluing lattice is small if the key subcomponents are small. Then attention is turned to triple gluing irreducible small lattices. The triple gluing irreducible [Special characters omitted.] lattices are introduced. The conditions which insure [Special characters omitted.] small are discovered. This dissertation also give some triple gluing irreducible small lattices by gluing [Special characters omitted.] 's. Finally, K-structured lattices are introduced. We prove that a K-structured lattice L is triple gluing irreducible if and only if [Special characters omitted.] . We prove that no 4-element antichain lies in u 1 /v1 of a K-structured small lattice. We also prove that some special lattices with 3-element antichains can not lie in u1 /v1 of a K-structured small lattice.
Description: viii, 87 leaves, bound : ill. ; 29 cm.; Thesis (Ph. D.)--University of Hawaii at Manoa, 2000.Sat, 01 Jan 2000 00:00:00 GMThttp://hdl.handle.net/10125/259362000-01-01T00:00:00ZHeeney, Xiang Xia HuangPotential Good Reduction of Degree 2 Rational Maps
http://hdl.handle.net/10125/25935
Abstract: We give a complete characterization of degree two rational maps on P1 with potential good reduction over local fields. We show this happens exactly when the map corresponds to an integral point in the moduli space M2. The proof includes an algorithm by which to conjugate any degree two rational map corresponding to an integral point in M2 into a map with unit resultant. The local fields result is used to solve the same problem for number fields with class number 1. Some additional results are given for degree 2 rational maps over Q. We also give a full description of post-critically finite maps in M2(Q), including the algorithm used to find them.
Description: Thesis (Ph. D.)--University of Hawaii at Manoa, 2012.Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/10125/259352012-01-01T00:00:00ZYap, DianeP-adic analysis and mock modular forms
http://hdl.handle.net/10125/25934
Abstract: A mock modular form f+ is the holomorphic part of a harmonic Maass form f. The non-holomorphic part of f is a period integral of a cusp form g, which we call the shadow of f+. The study of mock modular forms and mock theta functions is one of the most active areas in number theory with important works by Bringmann, Ono, Zagier, Zwegers, among many others. The theory has many wide-ranging applications: additive number theory, elliptic curves, mathematical physics, representation theory, and many others.
We consider arithmetic properties of mock modular forms in three different settings: zeros of a certain family of modular forms, coupling the Fourier coefficients of mock modular forms and their shadows, and critical values of modular L-functions.
For a prime p > 3, we consider j-zeros of a certain family of modular forms called Eisenstein series. When the weight of the Eisenstein series is p - 1, the j-zeros are j-invariants of elliptic curves with supersingular reduction modulo p. We lift these j-zeros to a p-adic field, and show that when the weights of two Eisenstein series are p-adically close, then there are j-zeros of both series that are p-adically close.
A direct method for relating the coefficients of shadows and mock modular forms is not known. This is considered to be among the first of Ono's Fundamental Problems for mock modular forms. The fact that a shadow can be cast by infinitely many mock modular forms, and the expected transcendence of generic mock modular forms pose serious obstructions to this problem. We solve these problems when the shadow is an integer weight cusp form. Our solution is p-adic, and it relies on our definition of an algebraic regularized mock modular form.
We use mock modular forms to compute generating functions for the critical values of modular L-functions. To obtain this result we derive an Eichler-Shimura theory for weakly holomorphic modular forms and mock modular forms. This includes an "Eichler-Shimura isomorphism", a "multiplicity two" Hecke theory, a correspondence between mock modular periods and classical periods, and a "Haberland-type" formula which expresses Petersson's inner product and a related antisymmetric inner product on M!k in terms of periods.
Description: 87 leaves, bound ; 29 cm.; Thesis (Ph. D.)--University of Hawaii at Manoa, 2010.Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/10125/259342011-01-01T00:00:00ZKent, Zachary A.Linear preservers and entire functions with restricted zero loci
http://hdl.handle.net/10125/25933
Abstract: Let T : R [x] → R [x] be a linear operator such that T[ xk] = gammakxk for all k = 0, 1, 2, ..., where gamma k ∈ R . The real sequence gkinfinity k=0 is called a multiplier sequence if for any p ∈ R [x], having only real zeros, T[ p] also has only real zeros. A characterization of all multiplier sequences that can be interpolated by rational functions is given. This partially solves a problem of G. Csordas and T. Craven, who asked for a characterization of all the meromorphic functions, Y(k), such that Yk infinityk=0 is a multiplier sequence.
An eight-year-old conjecture of I. Krasikov is proved. Several discrete analogues of classical inequalities for polynomials with only real zeros are obtained, along with results which allow extensions to a class of transcendental entire functions in the Laguerre-Polya class. A study of finite difference operators which preserve reality of zeros is initiated, and new results are proved.
Composition theorems and inequalities for polynomials having their zeros in a sector are obtained. These are analogs of classical results by Polya, Schur, and Turan. In addition, a result of Obreschkoff is used to show that the Jensen polynomials related to the Riemann xi-function have only real zeros up to degree 1017. Sufficient conditions are established for a linear transformation to map polynomials having zeros only in a sector to polynomials of the same type, and some multivariate extensions of these results are presented. A complete characterization is given for linear operators which preserve closed ("strict") half-plane stability in the univariate Weyl algebra. These results provide new information about a general stability problem posed formally by G. Csordas and T. Craven. In his 2011 AMS Bulletin article, D. G. Wagner describes recent activity in multivariate stable polynomial theory as "exciting work---elementary but subtle, and with spectacular consequences." Wagner points out that many of the recent advancements in the theory of multivariate stable polynomials are due to the pioneering work of J. Borcea and P. Branden. These results play an important role in the investigation of linear stability preservers in this dissertation.
Several different approaches to characterizing linear transformations which map polynomials having zeros only in one region of the complex plane to polynomials of the same type are explored. In addition, an open problem of S. Fisk is solved, and several partial results pertaining to open problems from the 2007 AIM workshop "Polya-Schur-Lax problems: hyperbolicity and stability preservers" are obtained.
Description: Thesis (Ph. D.)--University of Hawaii at Manoa, 2011.Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/10125/259332011-01-01T00:00:00ZChasse, Matthew NegusLinear Operators and the Distribution of Zeros of Entire Functions
http://hdl.handle.net/10125/25932
Abstract: Motivated by the work of Pólya, Schur, and Turán, a complete characterization of multiplier sequences for the Hermite polynomial basis is given. Laguerre's theorem and a remarkable curve theorem due to Pólya are generalized. Sufficient conditions for the location of zeros in certain strips in the complex plane are determined. Results pertaining to multiplier sequences and complex zero decreasing sequences for other polynomial sets are established.
Description: viii, 178 leaves, bound ; 29 cm.; Thesis (Ph. D.)--University of Hawaii at Manoa, 2007.Mon, 01 Jan 2007 00:00:00 GMThttp://hdl.handle.net/10125/259322007-01-01T00:00:00ZPiotrowski, AndrzejGeneralized Gelfand triples
http://hdl.handle.net/10125/11728
Description: Typescript.; Thesis (Ph. D.)--University of Hawaii, 1971.; Bibliography: leaves 73-74.; vi, 74 lFri, 01 Jan 1971 00:00:00 GMThttp://hdl.handle.net/10125/117281971-01-01T00:00:00ZCasteren, J.A. vanDual linear spaces generated by a non-Desarguesian configuration
http://hdl.handle.net/10125/11727
Abstract: A dual linear space is a partial projective plane which contains the intersection of every pair of its lines. Every dual linear space can be extended to a projective plane, usually infinite, by a sequence of one line extensions. Moreover, one may describe necessary conditions for the sequence of one line extensions to terminate after finitely many steps with a finite projective plane. A computer program that attempts to construct a finite projective plane from a given dual linear space by a sequence of one line extension has been written by Dr. Nation. In particular, one would like to extend a dual linear space containing a non-Desarguesian configuration to a finite projective plane of nonprime- power order. This dissertation studies the initial dual linear spaces to be used in this algorithm. The main result is that there are 105 non-isomorphic initial dual linear spaces containing the basic non-Desarguesian configuration.
Description: Mode of access: World Wide Web.; Thesis (Ph. D.)--University of Hawaii at Manoa, 2005.; Includes bibliographical references (leaves 160-161).; Electronic reproduction.; Also available by subscription via World Wide Web; viii, 161 leaves, bound ill. 29 cmSat, 01 Jan 2005 00:00:00 GMThttp://hdl.handle.net/10125/117272005-01-01T00:00:00ZSeffrood, Jiajia Yang GarciaGeometry and singularities of spatial and spherical curves
http://hdl.handle.net/10125/11726
Abstract: In the first part of this dissertation the spherical evolute, the spherical involute, the spherical orthotomic and the spherical antiorthotomic are investigated and their local diffeomorphic types are determined. The concept of the spherical conic is introduced. It is proven that the incident angle and reflection angle are equal for the spherical conic. The necessary and sufficient conditions for the spherical conic to be a circle are given. In the second part of this dissertation the ruled surfaces of normals and binormals of a regular space curve are locally classified under the left-right action according to the types of the curve. For this purpose some results are obtained on the relationship of the powers of terms in the Taylor series of an invertible function and its inverse.
Description: Mode of access: World Wide Web.; Thesis (Ph. D.)--University of Hawaii at Manoa, 2004.; Includes bibliographical references (leaves 113-114).; Electronic reproduction.; Also available by subscription via World Wide Web; vii, 114 leaves, bound ill. 29 cmThu, 01 Jan 2004 00:00:00 GMThttp://hdl.handle.net/10125/117262004-01-01T00:00:00ZXiong, JianfeiFinite group graded lie algebraic extensions and trefoil symmetric relativity, standard model, yang mills and gravity theories
http://hdl.handle.net/10125/11725
Abstract: We introduce the Quotient Group Graded Lie algebras, which involve graded structure constants. This structure is then used to obtain a graded extension of supersymmetry where diverse features of the Standard Model of elementary particles arise naturally. For the Minimal Vector Clover Extension of the symmetries of special relativity, we develop the extended superspace formalism in differential geometric language. We construct connections, curvature, and prove Bianchi identities both in coordinate and in symmetry covariant bases. We study also a connection making the Lorentz symmetry point dependent, its torsion and curvature. Moreover, we examine a transformation that removes noncommutativity from the Minimal Vector Clover Extension.
Description: Mode of access: World Wide Web.; Thesis (Ph. D.)--University of Hawaii at Manoa, 2004.; Includes bibliographical references (leaves 159-164).; Electronic reproduction.; Also available by subscription via World Wide Web; x, 164 leaves, bound ill. 29 cmTue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/10125/117252008-01-01T00:00:00ZWills, Luis AlbertoAutomated reasoning and machine learning
http://hdl.handle.net/10125/9963
Abstract: This dissertation introduces new theorem-proving strategies and uses these strategies to solve a wide variety of difficult problems requiring logical reasoning. It also shows how to use theorem-proving to solve the problem of learning mathematical concepts. Our first algorithm constructs formulas called Craig interpolants from the refutation proofs generated by contemporary theorem-provers using binary resolution, paramodulation, and factoring. This algorithm can construct the formulas needed to learn concepts expressible in the full first-order logic from examples of the concept. It can also find sentences which distinguish pairs of nonisomorphic finite structures. We then apply case analysis to solve hard problems such as the zebra problem, the pigeonhole problem, and the stable marriage problem. The case analysis technique we use is the first to be fully compatible with resolution and rewriting and powerful enough to solve these problems. Our primary new theorem-proving strategies generate subgoals and efficient sets of rules. We show how to divide problems into smaller parts with intermediate goals by reversing logical implications. We solve these subdivided parts by discovering efficient subsets of rules or by generating efficient new rules. We apply these and other new search strategies to solve difficult problems such as the 15-puzzle, central solitaire, TopSpin, Rubik's cube, and masterball. Our strategies apply universally to all such problems and can solve them quite efficiently: the 15-puzzle, Rubik's cube and masterball can all be done in 300 seconds. Finally we apply our search strategies to solve real-world problems such as sorting, solving equations and inverting nonsingular matrices.
Description: Thesis (Ph. D.)--University of Hawaii at Manoa, 1996.; Includes bibliographical references (leaves 140-144).; Microfiche.; x, 144 leaves, bound ill. 29 cmMon, 01 Jan 1996 00:00:00 GMThttp://hdl.handle.net/10125/99631996-01-01T00:00:00ZHuang, GuoxiangCombinatorial remedies
http://hdl.handle.net/10125/9962
Abstract: This dissertation consists of 3 chapters which consider distinct combinatorial problems. In the first chapter we consider objects known as groupies. A non-isolated vertex of a graph G is called a groupie if the average degree of the vertices connected to it is larger than or equal to the average degree of the vertices in G. An isolated vertex is a groupie only if all vertices of G are isolated. It is well known that every graph must contain at least one groupie. The graph Kn - e contains precisely 2 groupie vertices for n ≥2. In this chapter we derive a lower bound for the number of groupies in terms of the number of vertices of each particular degree. This shows, in particular, that any graph with 2 or more vertices must contain at least 2 groupies. In chapter 2 we show that, for a prime number p+n+1 , the number of pth powers in Sn+1 is n+1 times the number of pth powers in Sn. Here Sn denotes the symmetric group on n objects. Our technique also yields a recursion for calculating the number of r": powers in Sn+1. An analogous identity, and corresponding recursion, for pth powers containing a specified number of pi-cycles is also obtained. This generalizes work of Blum in the case p = 2, and Chernoff's work for general p. Finally, in chapter 3, we use techniques introduced by Giraud to obtain lower bounds for certain Ramsey Numbers. The Ramsey Number R(k,j) is defined to be the least positive integer n such that every n-vertex graph contains either a clique of order k or an independent set of order j. In particular we show that R (6, 6) ≤ 165, R (7, 7) ≤ 540, R (8, 8) ≤ 1870, R (9, 9) ≤ 6625, and R (10, 10) ≤ 23854 . These estimates replace bounds of 166, 574, 1982, 7042, and 25082, respectively.
Description: Thesis (Ph. D.)--University of Hawaii at Manoa, 1994.; Includes bibliographical references (leaves 29-30); Microfiche.; 30 leaves, bound ill. 29 cmSat, 01 Jan 1994 00:00:00 GMThttp://hdl.handle.net/10125/99621994-01-01T00:00:00ZMackey, John FletcherProblems in hyperbolic geometry
http://hdl.handle.net/10125/9961
Abstract: In this thesis, we discuss the proof that all convex polyhedral metrics can be realized in euclidean and hyperbolic 3-space. This result is accredited to A.D. Alexandrov and is fundamental in modern synthetic differential geometry. Nevertheless, gaps appear in currently acknowledged proofs: (1) It is necessary to prove that strictly convex metrics with 4 real vertices can be realized. (2) It must be shown that, within manifolds of convex polyhedra in E3 or H3, there exist submanifolds of degenerate polyhedra which are "thin" when mapped into manifolds of (abstract) strictly convex metrics. In this thesis we prove these statements. The remainder of the thesis is devoted to general hyperbolic geometry with emphasis on the synthetic point of view. We first construct horocyclic coordinates and use these to derive the Poincare model for the hyperbolic plane. Then we compute useful formulas for the curvature of a surface, and use these formulas to study C2 surfaces in H3, infinitesimal deformations of the horosphere, and curves of constant curvature in H2. Finally, we also prove that certain surfaces of rotation in E3 isometrically imbed in H3. These results, some of which are new, provide a background for synthetic methods underlying the theorem of Alexandrov.
Description: Thesis (Ph. D.)--University of Hawaii at Manoa, 1993.; Includes bibliographical references (leaf 124); Microfiche.; vii, 124 leaves, bound ill. 29 cmFri, 01 Jan 1993 00:00:00 GMThttp://hdl.handle.net/10125/99611993-01-01T00:00:00ZReiser, Edward J.Almost completely decomposable groups with two critical types and their endomorphism rings
http://hdl.handle.net/10125/9960
Abstract: An almost completely decomposable group with two critical types is a direct sum of rank-one groups and indecomposable rank-two groups. A complete set of near isomorphism invariants for an acd group with two critical types is the isomorphism class of the regulator and the isomorphism class of the regulator quotient; with one additional invariant, namely an element of a certain quotient group of (Ζ/m Ζ)^x , a complete set of isomorphism invariants for an acd group with two critical types is obtained. Finally, the endomorphism ring of an acd group with two critical types is computed and the resulting structure is used to give an example of two nearly isomorphic groups with non-isomorphic endomorphism rings.
Description: Thesis (Ph. D.)--University of Hawaii at Manoa, 1992.; Includes bibliographical references (leaves 48-49); Microfiche.; iv, 49 leaves, bound 29 cmWed, 01 Jan 1992 00:00:00 GMThttp://hdl.handle.net/10125/99601992-01-01T00:00:00ZLewis, WayneA covering space approach to (d,k) constrained codes
http://hdl.handle.net/10125/9959
Abstract: The capacity of the (d, k) constrained codes and of the (d, k) L level charge constrained codes is considered. The case of rational capacity is examined. and an error in the literature is corrected. This leads to an interesting (0.3)L = 4 level charge constrained code. The error control for this code is done using the finite field GF(3). A table of the ternary convolutional codes of greatest free distance is given for possible applications. The topological properties of the (d, k) constraint graphs are examined. The fundamental group of a constraint graph and covering spaces of a constraint graph are discussed. A constructive process for building a covering space of a constraint graph is given. The construction of (d, k) constrained block codes from covering spaces of the (d, k) constraint graph is examined. Several types of block codes are introduced. The base point codes consist of the (d, k) constrained sequences whose associated edge paths in the covering space are loops at a specified vertex. The parity point codes consist of the (d, k) constrained sequences whose associated edge paths in the covering space conned two specified vertices. It is shown that an [n, k] cyclic code can be constructed as a base point code for a 2^(n-k) fold covering of the (0,∞) constraint graph. Systematic (d, k) constrained block codes are constructed for detecting all single shift errors, drop in errors, and drop out errors. The average probability of an undetected error for the systematic (d, k) constrained block codes is shown to decrease exponentially with the parity length times the capacity of a (d, k) constrained code.
Description: Thesis (Ph. D.)--University of Hawaii at Manoa, 1992.; Includes bibliographical references (leaves 102-104); Microfiche.; ix, 104 leaves, bound ill. 29 cmWed, 01 Jan 1992 00:00:00 GMThttp://hdl.handle.net/10125/99591992-01-01T00:00:00ZPerry, Patrick NeilMaximum principles and Liouville theorems for elliptic partial differential equations
http://hdl.handle.net/10125/9958
Description: Typescript.; Thesis (Ph. D.)--University of Hawaii at Manoa, 1990.; Includes bibliographical references.; Microfiche.; vi, 96 leaves, bound ill. 29 cmMon, 01 Jan 1990 00:00:00 GMThttp://hdl.handle.net/10125/99581990-01-01T00:00:00ZZhou, ChipingNew classes of finite commutative rings
http://hdl.handle.net/10125/3076
Abstract: This dissertation introduces the concept of Q-Witt rings and SQ-Witt rings. A Q-Witt ring is defined as a finite quotient of a torsion free abstract Witt ring for an elementary 2-group G. Local Q-Witt rings are characterized using topological and ring theoretic tools. Q-Witt rings of the integral group ring Z[Z2] are classified and several properties are shown. An SQ-Witt ring is formed as a finite quotient of torsion free Witt rings of a formally real field. Recursive construction can be used to locate all SQ-Witt rings.
Description: Thesis (Ph. D.)--University of Hawaii at Manoa, 2003.; Includes bibliographical references (leaves 51-52).; Mode of access: World Wide Web.; Also available by subscription via World Wide Web; vi, 52 leaves, bound 29 cmWed, 01 Jan 2003 00:00:00 GMThttp://hdl.handle.net/10125/30762003-01-01T00:00:00ZVo, Monika