On Dual Definite Subspaces in Krein Space

摘要

Extensions of dual definite subspaces to dual maximal definite ones are described. The obtained results are applied to the classification of C-symmetries. The concepts of dual quasi maximal subspaces and quasi bases are introduced and studied. It is shown that complex shift g()g(+ia) of Hermite functions gn is an example of quasi bases in L2(R).