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Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

2002

Mathematics

Mathematics Faculty Works

Articles 1 - 3 of 3

Full-Text Articles in Physical Sciences and Mathematics

An Effective Version Of Belyi's Theorem, Lily S. Khadjavi Jan 2002

An Effective Version Of Belyi's Theorem, Lily S. Khadjavi

Mathematics Faculty Works

We compute bounds on covering maps that arise in Belyi's Theorem. In particular, we construct a library of height properties and then apply it to algorithms that produce Belyi maps. Such maps are used to give coverings from algebraic curves to the projective line ramified over at most three points. The computations here give upper bounds on the degree and coefficients of polynomials and rational functions over the rationals that send a given set of algebraic numbers to the set {0,1,∞} with the additional property that the only critical values are also contained in {0,1,∞}.


Ideal Theory In Prüfer Domains - An Unconventional Approach, Edward Mosteig Jan 2002

Ideal Theory In Prüfer Domains - An Unconventional Approach, Edward Mosteig

Mathematics Faculty Works

In Prüfer domains of finite character, ideals are represented as finite intersections of special ideals which are proper generalizations of the classical primary ideals. We show that representations of ideals as shortest intersections of primal or quasi-primary ideals exist and are unique. Moreover, every non-zero ideal is the product of uniquely determined pairwise comaximal quasi-primary ideals. Semigroups of primal and quasi-primary ideals with fixed associated primes are also investigated in arbitrary Prüfer domains. Their structures can be described in terms of the value groups of localizations.


Valuations And Filtrations, Edward Mosteig Jan 2002

Valuations And Filtrations, Edward Mosteig

Mathematics Faculty Works

The classical theory of Gröbner bases, as developed by Bruno Buchberger, can be expanded to utilize objects more general than term orders. Each term order on the polynomial ring k[x] produces a filtration of k[x] and a valuation ring of the rational function field k(x). The algorithms developed by Buchberger can be performed by using directly the induced valuation or filtration in place of the term order. There are many valuations and filtrations that are suitable for this general computational framework that are not derived from term orders, even after a change of variables. Here we study how to translate …