%0 Journal Article
%T Q-functions and boundary triplets of nonnegative operators
%A Yury Arlinskii
%A Seppo Hassi
%J Mathematics
%D 2013
%I arXiv
%X Operator-valued $Q$-functions for special pairs of nonnegative selfadjoint extensions of nonnegative not necessarily densely defined operators are defined and their analytical properties are studied. It is shown that the Kre\u\i n-Ovcharenko statement announced in \cite{KrO2} is valid only for $Q$-functions of densely defined symmetric operators with finite deficiency indices. A general class of boundary triplets for a densely defined nonnegative operator is constructed such that the corresponding Weyl functions are of Kre\u\i n-Ovcharenko type.
%U http://arxiv.org/abs/1309.6882v1