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JOURNALS // Zapiski Nauchnykh Seminarov POMI // Archive

Zap. Nauchn. Sem. LOMI, 1989 Volume 178, Pages 120–145 (Mi znsl4678)

This article is cited in 6 papers

Estimates for the difference of the fractional powers of self-adjoint operators under unbounded perturbations

M. Sh. Birman, M. Z. Solomyak


Abstract: For positive self-adjoint operators $A_0$, $A_1$ on Hilbert spaces $\mathcal{H}_0$, $\mathcal{H}_1$ and for an operator $\mathcal{J}: \mathcal{H}_0\to\mathcal{H}_1$, the following estimate is obtained:
$$ |\alpha^{-1}(A_1^\alpha\mathcal{J}-\mathcal{J}A_0^\alpha)|_\gamma\leqslant A_1^{-\delta}(A_1\mathcal{J}-\mathcal{J}A_0)A_0^{-\delta},\quad 2\delta=1-\alpha,\quad-1<\alpha<1. $$
Here $|\cdot|_\gamma$ denotes the norm in some symmetric-normed operator ideal $\gamma$. Some generalizations of this estimate are presented too. Applications to the differential operators are discussed.

UDC: 517.43


 English version:
Journal of Soviet Mathematics, 1992, 61:2, 2018–2035

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