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Păstorel Gaşpar

Publications and source records attributed to Păstorel Gaşpar.

2 recordsLinked to original sources

Dilations on locally Hilbert spaces

The principal theorem of Sz.-Nagy on dilation of a positive definite Hilbert space operator valued function has played a central role in the development of the non-self-adjoint operator theory. In this paper we introduce the positive definiteness for locally Hilbert space operator valued kernels, we prove an analogue of the Sz.-Nagy dilation theorem and, as application, we obtain dilation results for locally contractions and locally $ρ$ - contractions as well as for locally semi-spectral measures.

math.FA↗

A note on partial isometries on pseudo-Hilbert spaces

The aim of this paper is to show that two accessible subspaces in the Loynes $\mathcal{Z}$ - space $\Hc$ are the initial and final space of a partial gramian isometry, respectively if the norm of the difference of the associated gramian selfadjoint projections is strictly less than 1.

math.FA↗