Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Mathematics. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography : leaves 104-110. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: leaves 74-75. / Ph.D.

The final Chapter concerns a problem of partitioning graphs subject to certain restrictions. We prove that several subproblems are NP-complete.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis (M.S.)--Missouri University of Science and Technology, 2010. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed July 19, 2010) Includes bibliographical references (p. 56-62).

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The main objective of our study is enumerating spanning trees (G) and perfect matchings PM(G) on graphs G and lattices L. We demonstrate two methods of enumerating spanning trees of any connected graph, namely the matrix-tree theorem and as a special value of the Tutte polynomial T(G; x; y). We present a general method for counting spanning trees on lattices in d 2 dimensions. In particular we apply this method on the following regular lattices with d = 2: rectangular, triangular, honeycomb, kagomé, diced, 9 3 lattice and its dual lattice to derive a explicit formulas for the number of spanning trees of these lattices of finite sizes. Regarding the problem of enumerating of perfect matchings, we prove Cayley’s theorem which relates the Pfaffian of a skew symmetric matrix to its determinant. Using this and defining the Pfaffian orientation on a planar graph, we derive explicit formula for the number of perfect matchings on the following planar lattices; rectangular, honeycomb and triangular. For each of these lattices, we also determine the bulk limit or thermodynamic limit, which is a natural measure of the rate of growth of the number of spanning trees (L) and the number of perfect matchings PM(L). An algorithm is implemented in the computer algebra system SAGE to count the number of spanning trees as well as the number of perfect matchings of the lattices studied. / AFRIKAANSE OPSOMMING: Die hoofdoel van ons studie is die aftelling van spanbome (G) en volkome afparings PM(G) in grafieke G en roosters L. Ons beskou twee metodes om spanbome in ’n samehangende grafiek af te tel, naamlik deur middel van die matriks-boom-stelling, en as ’n spesiale waarde van die Tutte polinoom T(G; x; y). Ons behandel ’n algemene metode om spanbome in roosters in d 2 dimensies af te tel. In die besonder pas ons hierdie metode toe op die volgende reguliere roosters met d = 2: reghoekig, driehoekig, heuningkoek, kagomé, blokkies, 9 3 rooster en sy duale rooster. Ons bepaal eksplisiete formules vir die aantal spanbome in hierdie roosters van eindige grootte. Wat die aftelling van volkome afparings aanbetref, gee ons ’n bewys van Cayley se stelling wat die Pfaffiaan van ’n skeefsimmetriese matriks met sy determinant verbind. Met behulp van hierdie stelling en Pfaffiaanse oriënterings van planare grafieke bepaal ons eksplisiete formules vir die aantal volkome afparings in die volgende planare roosters: reghoekig, driehoekig, heuningkoek. Vir elk van hierdie roosters word ook die “grootmaat limiet” (of termodinamiese limiet) bepaal, wat ’n natuurlike maat vir die groeitempo van die aantaal spanbome (L) en die aantal volkome afparings PM(L) voorstel. ’n Algoritme is in die rekenaaralgebra-stelsel SAGE geimplementeer om die aantal spanboome asook die aantal volkome afparings in die toepaslike roosters af te tel.

In 1961, P. W. Kasteleyn provided a baffling-looking solution to an apparently simple tiling problem: how many ways are there to tile a rectangular region with dominos? We examine his proof, simplifying and clarifying it into this nearly self-contained work.

Even if an encryption algorithm is mathematically strong, humans inevitably make for a weak link in most security protocols. A sufficiently threatening adversary will typically be able to force people to reveal their encrypted data. Methods of deniable encryption seek to mend this vulnerability by allowing for decryption to alternate data which is plausible but not sensitive. Existing schemes which allow for deniable encryption are best suited for use by parties who wish to communicate with one another. They are not, however, ideal for personal data storage. This paper develops a plausibly-deniable encryption system for use with personal data storage, such as hard drive encryption. This is accomplished by narrowing the encryption algorithm’s message space, allowing different plausible plaintexts to correspond to one another under different encryption keys.

An isohedral tiling is a tiling of congruent polygons that are also transitive, which is to say the configuration of degrees of vertices around each face is identical. Regular tessellations, or tilings of congruent regular polygons, are a special case of isohedral tilings. Viewing these tilings as graphs in planes, both Euclidean and non-Euclidean, it is possible to pose various problems of enumeration on the respective graphs. In this paper, we investigate some near-regular isohedral tilings of triangles and quadrilaterals in the hyperbolic plane. For these tilings we enumerate vertices as classified by number of edges in the shortest path to a given origin, by combinatorially deriving their respective generating functions.

Orientador: Jose Plinio de Oliveira Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-05T07:47:09Z (GMT). No. of bitstreams: 1 Bovo_Eduardo_M.pdf: 3427598 bytes, checksum: 757ebc9282f3c010e155c26ec46fb42a (MD5) Previous issue date: 2005 / Resumo: Neste trabalho são desenvolvidos conceitos algébricos, analíticos e combinatórios que culminam no Teorema de Enumeração de Pólya; bem como são fornecidas muitas de suas aplicações em enumeração de padrões (grafos, colorações geométricas, tipos e permutações, etc). Tal teorema clássico, que tem suas bases em Teoria dos Grupos, utiliza fundamentalmente o conceito de funções geradoras, o que permite grande generalidade e computabilidade de resultados. Finalmente são apresentadas algumas generalizações do resultado principal, aplicações destas e também uma importante interpretação probabilística / Abstract: In this dissertation we present algebraic, analytic and combinatorial results that are used to prove Polya's Enumeration Theorem. Applications to counting patterns (graphs, colourings, permutations, etc.) are given. This classical Theorem has its foundations on the theory of groups and uses, mainly, the concept of generating functions which allows great generality and computability of results. At the end some generalizations of the main theorem are given including applications and, aiso, an important probabilistic interpretation / Mestrado / Combinatoria Enumerativa / Mestre em Matemática Aplicada