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JOURNALS // Matematicheskii Sbornik // Archive

Mat. Sb., 2000 Volume 191, Number 12, Pages 61–76 (Mi sm529)

This article is cited in 10 papers

Setting and solving several factorization problems for integral operators

N. B. Engibaryan

Byurakan Astrophysical Observatory, National Academy of Sciences of Armenia

Abstract: The problem of factorization
$$ I-K=(I-U_-)(I-U_+), $$
is considered. Here $I$ is the identity operator, $K$ is a fixed integral operator of Fredholm type:
$$ (Kf)(x)=\int_a^bk(x,t)f(t)\,dt, \qquad -\infty\leqslant a<b\leqslant+\infty, $$
$U_\pm$ are unknown upper and lower Volterra operators. Classes of generalized Volterra operators $U_\pm$ are introduced such that $I-U_\pm$ are not necessarily invertible operators in the spaces of functions on $(a,b)$ under consideration. A combination of the method of non-linear factorization equations and a priori estimates brings forth new results on the existence and properties of the solution to this problem for $k\geqslant 0$, both in the subcritical case $\mu<1$ and in the critical case $\mu=1$, where $\mu=r(K)$ the spectral radius of the operator $K$. In addition, the problem of non-Volterra factorization is posed and studied, when the kernels of $U_+$ and $U_-$ vanish on some parts $S_-$ and $S_+$ of the domain $S=(a,b)^2$ such that $S_+\cup S_-=S$.

UDC: 517.9

MSC: 45B05, 45D05, 47Gxx

Received: 27.04.1999

DOI: 10.4213/sm529


 English version:
Sbornik: Mathematics, 2000, 191:12, 1809–1825

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© Steklov Math. Inst. of RAS, 2026