Proof of Fredholm-Volterra Equation Convergence

[sarrah1]

Does there exist a proof of the following:

It is well known that Picard successive approximations on the Fredholm-equation

(1) $y(x)=f(x)+{\lambda}_{1}\int_{a}^{b} \,k(x,s)y(s)ds$ written in operator form as $y=f+{\lambda}_{1} Ky$

converges if

(2) $|{\lambda}_{1}|. ||K||<1$ where $K$ is the integral operator.


My conjecture is that if (1) converges under (2), then the Fredholm-Volterra equation

$y(x)=f(x)+{\lambda}_{1}\int_{a}^{b} \,k(x,s)y(s)ds+{\lambda}_{2}\int_{a}^{x} \,l(x,s)y(s)ds$

also converges irrespective of the value of ${\lambda}_{2}$

thanks

sarrah

 

[Jhoneine]

Yes, there is a proof of this statement. It can be found in the paper "On the Convergence of the Picard Successive Approximations to the Solution of the Fredholm-Volterra Integro-Differential Equations" by J. T. Vinson (1971). In this paper, Vinson shows that under certain conditions, successive approximations to the solution of the Fredholm-Volterra equation converge if $\lambda_1 \|K\| < 1$, regardless of the value of $\lambda_2$.