Vol. 16, No. 2, 1966

Download this article
Download this article. For screen
For printing
Recent Issues
Vol. 332: 1  2
Vol. 331: 1  2
Vol. 330: 1  2
Vol. 329: 1  2
Vol. 328: 1  2
Vol. 327: 1  2
Vol. 326: 1  2
Vol. 325: 1  2
Online Archive
Volume:
Issue:
     
The Journal
About the journal
Ethics and policies
Peer-review process
 
Submission guidelines
Submission form
Editorial board
Officers
 
Subscriptions
 
ISSN 1945-5844 (electronic)
ISSN 0030-8730 (print)
 
Special Issues
Author index
To appear
 
Other MSP journals
Integral equations and product integrals

Burrell Washington Helton

Vol. 16 (1966), No. 2, 297–322
Abstract

H. S. Wall, J. S. MacNerney and T. H. Hildebrandt have shown interdependencies between the equations

       ∏x                     ∫ x
f(x) = a  (1 + dg) and f(x) = 1+ a f dg;

this paper extends and consolidates some of their results. Let S be a linearly ordered set, R be a normed ring, and OA0 and OM0 be classes of functions G from S ×S to R for which

∫         ∫
b|G (I)−   G| = 0
a         I

and

∫ b           ∏
|[1+ G (I)]−    (1 + G)| = 0,
a             I

respectively. We show the following. If G has bounded variation, G OA0 if and only if G OM0. For some rings, the existence of abG(I) and a b[1 + G(I)] imply that G OA0 and OM0, respectively. This is used to prove a product integral solution of integral equations such as

                 ∫ x
f(x) = f(a)+ (RL )  (fG + Hf ),
a

where f is a function from S to R and G and H are functions from S × S to R. Then these results are used (a) to show that each nonsingular m × m matrix of complex numbers has n distinct n-th roots, (b) to show that, with some restrictions, i=1Ai exists if and only if i=1(1 + Ai) exists and (c) to find solutions of integrals equations such as

             ∫
x n
f (x) = f(a)+  a f dg.

Mathematical Subject Classification
Primary: 45.00
Milestones
Received: 8 May 1964
Published: 1 February 1966
Authors
Burrell Washington Helton