For selfadjoint elliptic operators in divergence form with ?-periodic coefficients of even order 2m ? 4 we approximate the resolvent energy operator norm $$ {\left\Vert \bullet \right\Vert}_{L^2\to {H}^m} a remainder ?2 as ? ? 0.

We prove an explicit formula for the spectral expansions in L(R) generated by selfadjoint differential operators (−1) d dx2n + n−1

In this work we prove that the eigenvalues of $n$-dimensional massive Dirac operator $\mathscr{D}_0 + V$, $n\ge2$, perturbed by a possibly non-Hermitian potential $V$, are localized in union two disjoint disks complex plane, provided $V$ is sufficiently small with respect to mixed norms $L^1_{x_j} L^\infty_{\widehat{x}_j}$, for $j\in\{1,\dots,n\}$. massless case, instead discrete spectrum empty...

\( \newcommand\norm[1]{\left\lVert#1\right\rVert}\newcommand\normx[1]{\left\Vert#1\right\Vert} \)In this paper several tensorial norm inequalities for continuous functions of selfadjoint operators in Hilbert spaces have been obtained. Multiple are obtained with variations due to the convexity properties mapping $f$$$\norm{(1\otimes B-A\otimes 1)^{-1}[\operatorname{exp}(1\otimes B)-\operatorname...