Abstract
This thesis deals with computational methods in algebra, mainly focusing on the concept of Gröbner and SAGBI bases in noncommutative algebras. The material has a natural division into two parts. The first part is a rather extensive treatment of the basic theory of Gröbner bases and SAGBI bases in the noncommutative polynomial ring. The second part is a collection of six papers.
In the first paper we investigate, for quotients of the noncommutative polynomial ring, a property that implies finiteness of Gröbner bases computation, and examine its connection with Noetherianity. We propose a Gröbner bases theory for factor algebras, of particular interest for onesided ideals, and show a few applications, e.g. how to compute (onesided) syzygy modules. The material of the third paper is in some sense related to the contents of this first paper; in the third paper, the theory of SAGBI bases is extended to factor algebras.
The second and fourth paper concerns composition of polynomials. In the first of those two papers, we give sufficient and necessary conditions on a set of polynomials to guarantee that the property of being a noncommutative Gröbner basis is preserved after composition by this set. The latter paper treats the same problem for SAGBI bases.
In the fifth paper we introduce the concept of biautomaton algebras, generalizing the automaton algebras previously defined by Ufnarovski. A biautomaton algebra is a quotient of the free algebra, defined by a binomial ideal admitting a Gröbner basis which can be encoded as a regular set; we call such a Gröbner basis regular. We give several examples of biautomaton algebras, and show how automata connected to regular Gröbner bases can be used to perform reduction.
In the last paper we investigate various important properties of regular languages associated with quotients of the free associative algebra. We suggest a generalization of a graph for normal words introduced by Ufnarovski, applicable to testing Noetherian properties of automaton algebras. Finally we show an alternative way to compute the generators for the Jacobson radical of any automaton monomial algebra.
In the first paper we investigate, for quotients of the noncommutative polynomial ring, a property that implies finiteness of Gröbner bases computation, and examine its connection with Noetherianity. We propose a Gröbner bases theory for factor algebras, of particular interest for onesided ideals, and show a few applications, e.g. how to compute (onesided) syzygy modules. The material of the third paper is in some sense related to the contents of this first paper; in the third paper, the theory of SAGBI bases is extended to factor algebras.
The second and fourth paper concerns composition of polynomials. In the first of those two papers, we give sufficient and necessary conditions on a set of polynomials to guarantee that the property of being a noncommutative Gröbner basis is preserved after composition by this set. The latter paper treats the same problem for SAGBI bases.
In the fifth paper we introduce the concept of biautomaton algebras, generalizing the automaton algebras previously defined by Ufnarovski. A biautomaton algebra is a quotient of the free algebra, defined by a binomial ideal admitting a Gröbner basis which can be encoded as a regular set; we call such a Gröbner basis regular. We give several examples of biautomaton algebras, and show how automata connected to regular Gröbner bases can be used to perform reduction.
In the last paper we investigate various important properties of regular languages associated with quotients of the free associative algebra. We suggest a generalization of a graph for normal words introduced by Ufnarovski, applicable to testing Noetherian properties of automaton algebras. Finally we show an alternative way to compute the generators for the Jacobson radical of any automaton monomial algebra.
Original language  English 

Qualification  Doctor 
Awarding Institution 

Supervisors/Advisors 

Award date  2001 Oct 5 
Publisher  
ISBN (Print)  9162849697 
Publication status  Published  2001 
Bibliographical note
Defence detailsDate: 20011005
Time: 10:15
Place: Matematikcentrum, sal C
External reviewer(s)
Name: Apel, Joachim
Title: Prof
Affiliation: University of Leipzig, Germany

Subject classification (UKÄ)
 Mathematics
Keywords
 gruppteori
 algebra
 algebraisk geometri
 fältteori
 Talteori
 group theory
 algebraic geometry
 field theory
 Matematik
 Number Theory
 regular languages
 Mathematics
 composition of polynomials
 factor algebras
 Gröbner bases
 SAGBI bases