Let U be a weakly closed nest algebra module acting on a Hilbert space H.Given two operators X and Y in B(H),a necessary and sufficient condition for the existe
Some sufficient conditions for the F-Sobolev inequality for symmetric forms are presented in terms of new Cheeger's constants. Meanwhile, an estimate of the
In this paper, we prove that the norm closure of all linear combinations of two unitary operators is equal to the norm closure of all invertible operators in B(