Distances between composition operators

The norm distance between two composition operators is calculated in select cases

A Proof of the Riemann hypothesis The new version contains a change in Definition 3.4, resulting in simpler proofs of theorems in Sections 3 and 4. Also, important proof in Sec.5 has been modified, for completeness and clarity

The function $G(z) = \int_0^\infty \xi^{z-1}(1+\exp(\xi))^{-1} \, d\xi$ is analytic and has the same zeros as the Riemann zeta function in the critical strip $D = \{z \in {\mathbf C} : 0 < \Re z < 1\}$. This paper combines some novel methods about indefinite integration, indefinite convolutions and inversions of Fourier transforms with numerical ranges of operators to prove the Riemann hypothesis.Comment: 26 pages in .pdf This version changes Definition 3.4, enabling changes the statements of Theorems in Sec.4, and thus enabling a clearer proof in Sec.

Characteristic functions and joint invariant subspaces

Let T:=[T_1,..., T_n] be an n-tuple of operators on a Hilbert space such that T is a completely non-coisometric row contraction. We establish the existence of a "one-to-one" correspondence between the joint invariant subspaces under T_1,..., T_n, and the regular factorizations of the characteristic function associated with T. In particular, we prove that there is a non-trivial joint invariant subspace under the operators T_1,..., T_n, if and only if there is a non-trivial regular factorization of the characteristic function. We also provide a functional model for the joint invariant subspaces in terms of the regular factorizations of the characteristic function, and prove the existence of joint invariant subspaces for certain classes of n-tuples of operators. We obtain criterions for joint similarity of n-tuples of operators to Cuntz row isometries. In particular, we prove that a completely non-coisometric row contraction T is jointly similar to a Cuntz row isometry if and only if the characteristic function of T is an invertible multi-analytic operator.Comment: 35 page

Free holomorphic functions on the unit ball of B(H)^n

We develop a theory of holomorphic functions in several noncommuting (free) variables and thus provide a framework for the study of arbitrary n-tuples of operators. The main topics are the following: Free holomorphic functions and Hausdorff derivations; Cauchy, Liouville, and Schwartz type results for free holomorphic functions; Algebras of free holomorphic functions; Free analytic functional calculus and noncommutative Cauchy transforms; Weierstrass and Montel theorems for free holomorphic functions; Free pluriharmonic functions and noncommutative Poisson transforms; Hardy spaces of free holomorphic functions.Comment: 51 page

Bounds on positive interior transmission eigenvalues

The paper contains lower bounds on the counting function of the positive eigenvalues of the interior transmission problem when the latter is elliptic. In particular, these bounds justify the existence of an infinite set of interior transmission eigenvalues and provide asymptotic estimates from above on the counting function for the large values of the wave number. They also lead to certain important upper estimates on the first few interior transmission eigenvalues. We consider the classical transmission problem as well as the case when the inhomogeneous medium contains an obstacle.Comment: We corrected inaccuracies cost by the wrong sign in the Green formula (17). In particular, the sign in the definition of \sigma was change