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math-ph2022
Perturbation of eigenvalues of the Klein Gordon operators II
Krešimi Veselić
We give estimates for the changes of the eigenvalues of the Klein Gordon operator under the change of the potential. In some relevant situations we improve the existing estimates.…
math-ph2017
Diagonalization of indefinite saddle point forms
Luka Grubišić, Vadim Kostrykin, Konstantin A. Makarov +2
We obtain sufficient conditions that ensure block diagonalization (by a direct rotation) of sign-indefinite symmetric sesquilinear forms as well as the associated operators that ar…