Minimum of quadratic forms with respect to Fuchsian groups. I.

1976 ◽  
Vol 1976 (286-287) ◽  
pp. 341-368 ◽  
Keyword(s):  
Quadratic Forms ◽  
Fuchsian Groups

27.—Generating Sets for Fuchsian Groups

1975 ◽  
Vol 72 (4) ◽  
pp. 317-326 ◽  
Author(s):  
J. H. H. Chalk ◽  
B. G. A. Kelly
Keyword(s):  
Quadratic Forms ◽  
Fundamental Region ◽  
Fuchsian Groups ◽  
Quaternion Algebras ◽  
Generating Sets ◽  
Complete Set ◽  
Explicit Bounds

SynopsisFor a class of Fuchsian groups, which includes integral automorphs of quadratic forms and unit groups of indefinite quaternion algebras, it is shown that the geometry of a suitably chosen fundamental region leads to explicit bounds for a complete set of generators.

scholarly journals Abstract theory of packings and coverings. I.

1959 ◽  
Vol 4 (2) ◽  
pp. 92-95 ◽  
Author(s):  
A. M. Macbeath
Keyword(s):  
Convex Body ◽  
Complex Plane ◽  
Quadratic Forms ◽  
Lattice Points ◽  
Fuchsian Groups ◽  
Linear Groups ◽  
Abstract Theory ◽  
Basic Ideas ◽  
Groups Of Transformations

The aim of this note is to examine the basic ideas underlying Minkowski's theorem on lattice points in a symmetrical convex body and related results of Blichfeldt, and to indicate how these can be generalized. Theorems analogous to Minkowski's, on the automorphisms of quadratic forms and other linear groups and on Fuchsian groups of transformations in the complex plane, have been obtained by Siegel [6] and Tsuji [7], Generalizations which include these are due to Chabauty [2] and Santalo [5].

Groups of units of zero ternary quadratic forms

1981 ◽  
Vol 88 (1-2) ◽  
pp. 141-157 ◽  
Author(s):  
Colin Maclachlan
Keyword(s):  
Finite Index ◽  
Quadratic Forms ◽  
Modular Group ◽  
Conjugacy Classes ◽  
Rational Integer ◽  
Fuchsian Groups ◽  
Integer Coefficients ◽  
Ternary Quadratic Forms

SynopsisThe groups of units of indefinite ternary quadratic forms with rational integer coefficients contain subgroups of index two which are isomorphic to Fuchsian groups and which, for zero forms, are commensurable with the classical modular group. This is used to obtain a family of forms whose groups are representatives of the conjugacy classes of maximal groups associated with zero forms. The signatures of the groups of the forms in this family are determined and it is shown that the group associated to any zero form is isomorphic to a subgroup of finite index in the group of one of three particular forms. This last result should be compared with the corresponding result by Mennicke on non-zero forms.

XXV.—On the Groups of Units of Ternary Quadratic Forms with Rational Coefficients

1967 ◽  
Vol 67 (4) ◽  
pp. 309-352 ◽  
Author(s):  
J. Mennicke
Keyword(s):  
Finite Number ◽  
Quadratic Forms ◽  
Rational Integer ◽  
Fuchsian Groups ◽  
Finitely Generated ◽  
Integer Coefficients ◽  
Ternary Quadratic Forms ◽  
Complete Survey

SynopsisFuchsian groups that are unit groups of ternary quadratic forms with rational integer coefficients are studied. By means of the well-known Nielsen classification of finitely generated Fuchsian groups, a complete survey of the unit groups is given. For this, we have to use the arithmetical methods of B. W. Jones. In the second part, the relations between Fuchsian groups arising from different quadratic forms are studied. It turns out that, with a finite number of exceptions, all these Fuchsian groups are subgroups of a particular one.

Existence

2017 ◽  
Author(s):  
Bernhard M¨uhlherr ◽  
Holger P. Petersson ◽  
Richard M. Weiss
Keyword(s):  
Division Algebra ◽  
Quadratic Forms ◽  
Structure Theorem ◽  
Quadratic Extension ◽  
Quadratic Space ◽  
Division Algebras ◽  
Separable Extension ◽  
Valued Fields ◽  
Quaternion Division Algebra

This chapter proves that Bruhat-Tits buildings exist. It begins with a few definitions and simple observations about quadratic forms, including a 1-fold Pfister form, followed by a discussion of the existence part of the Structure Theorem for complete discretely valued fields due to H. Hasse and F. K. Schmidt. It then considers the generic unramified cases; the generic semi-ramified cases, the generic ramified cases, the wild unramified cases, the wild semi-ramified cases, and the wild ramified cases. These cases range from a unique unramified quadratic space to an unramified separable quadratic extension, a tamely ramified division algebra, a ramified separable quadratic extension, and a unique unramified quaternion division algebra. The chapter also describes ramified quaternion division algebras D₁, D₂, and D₃ over K containing a common subfield E such that E/K is a ramified separable extension.

Totally Wild Quadratic Forms of Type E7

2017 ◽  
Author(s):  
Bernhard M¨uhlherr ◽  
Holger P. Petersson ◽  
Richard M. Weiss
Keyword(s):  
Division Algebra ◽  
Quadratic Forms ◽  
Quadratic Space ◽  
Trace Map ◽  
Quaternion Division Algebra

This chapter assumes that (K, L, q) is a totally wild quadratic space of type E₇. The goal is to prove the proposition that takes into account Λ‎ of type E₇, D as the quaternion division algebra over K whose image in Br(K) is the Clifford invariant of q, and the trace and trace map. The chapter also considers two other propositions: the first states that if the trace map is not equal to zero, then the Moufang residues R₀ and R₁ are not indifferent; the second states that if the trace map is equal to zero, then the Moufang residues R₀ and R₁ are both indifferent.

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