On the connexion of algebraic functions with automorphic functions

1898 ◽  
Vol 63 (389-400) ◽  
pp. 267-268 ◽  

If u and z are variables connected by an algebraic equation, they are, in general, multiform functions of each other; the multiformity can be represented by a Riemann surface, to each point of which corresponds a pair of values of u and z . Poincaré and Klein have proved that a variable t exists, of which u and z are uniform automorphic functions; the existence-theorem, however, does not connect t analytically with u and z . When the genus ( genre, Geschlecht ) of the algebraic relation is zero oi unity, t can be found by known methods; the automorphic functions required are rational functions, and doubly periodic functions, in the two case respectively.

It is well known that if f ( u, z ) = 0 . . . . . . . . . (1) is the equation of an algebraic curve of genus ( genre, Geschlecht ) zero, then u and z can be expressed as rational functions of a single variable t . If, however, the genus of the curve (1) is unity, u and z can be expressed as uniform elliptic functions of a variable t . The natural extension of these results was effected in 1881 by the discovery of automorphic functions; whatever be the genus of the curve (1), u and z can be expressed as uniform automorphic functions of a new variable.


1979 ◽  
Vol 86 (3) ◽  
pp. 427-435 ◽  
Author(s):  
Paul Milnes

AbstractCompact right topological groups appear naturally in topological dynamics. Some continuity properties of the one arising as an enveloping semigroup from the distal function are considered here (and, by way of comparison, the enveloping semigroups arising from two almost automorphic functions are discussed). The continuity properties are established either explicitly or by citing a theorem which is proved here and gives some characterizations of almost periodic functions. One characterization is proved using the result (essentially due to W. A. Veech) that a distal, almost automorphic function is almost periodic. A proof of this last result is also given.


1952 ◽  
Vol 4 ◽  
pp. 136-148
Author(s):  
S. Beatty ◽  
N. D. Lane

Let F(z, u) denote1where F1(z),… , Fn(z) are rational functions of z with complex coefficients. We shall speak of F (z, u) = 0 as the fundamental algebraic equation and shall adopt z as the independent variable and u as the dependent, except in § 4, where we use x and y instead of them, and where it is understood that x and y are connected birationally with z and u.


1930 ◽  
Vol 2 (2) ◽  
pp. 102-107 ◽  
Author(s):  
M. Mursi

An algebraic equationdetermines, in general, s as a many valued function of z. If s and z can be expressed as one valued functions of a third variable t, then t is called the uniformising variable. As Poincaré showed, s and z are automorphic functions of t.


1996 ◽  
Vol 38 (2) ◽  
pp. 249-253
Author(s):  
A. F. Beardon

If Г is a discrete Möbius group acting on the upper half-plane ℋ of the complex plane, the quotient space ℋ/Г is a Riemann surface ℛ and the automorphic functions on Г correspond to meromorphic functions on ℛ. If Г is a nondiscrete Möbius group acting on ℋ, then ℋ/Г is no longer a Riemann surface, and it is obvious that in this case there are no nonconstant automorphic functions on Г. The situation for automorphic forms is quite different. Automorphic forms of integral dimension for a discrete group Г correspond to meromorphic differentials on ℛ, but even if Г is nondiscrete it may still support nontrivial automorphic forms. The problem of classifying those nondiscrete Möbius groups which act on ℋ and which support nonconstant automorphic forms of arbitrary real dimension was raised and solved (rather indirectly) in [2] where, roughly speaking, function-theoretic methods are used to analyse all possible polynomial automorphic forms of integral dimension, and the results obtained then used to analyse the more general situation.


Sign in / Sign up

Export Citation Format

Share Document