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Triangle partition maps form a family that includes many, if not most, well-known multidimensional continued fraction algorithms. This paper begins the exploration of the functional analysis behind the transfer operator of each of these…

Dynamical Systems · Mathematics 2020-08-17 Ilya Amburg , Thomas Garrity

We study Clark measures associated with general two-variable rational inner functions (RIFs) on the bidisk, including those with singularities, and with general $d$-variable rational inner functions with no singularities. We give precise…

Functional Analysis · Mathematics 2024-10-29 John T. Anderson , Linus Bergqvist , Kelly Bickel , Joseph A. Cima , Alan A. Sola

This paper is a direct continuation of "Functional analysis behind a Family of Multidimensional Continued Fractions: Part I," in which we started the exploration of the functional analysis behind the transfer operators for triangle…

Dynamical Systems · Mathematics 2020-08-19 Ilya Amburg , Thomas Garrity

We describe a generalization of the notion of a Hilbert space model of a function in the Schur class of the bidisc. This generalization is well adapted to the investigation of boundary behavior at a mild singularity of the function on the…

Complex Variables · Mathematics 2012-03-30 J. Agler , R. Tully-Doyle , N. J. Young

Marginalization -- summing a function over all assignments to a subset of its inputs -- is a fundamental computational problem with applications from probabilistic inference to formal verification. Despite its computational hardness in…

Computational Complexity · Computer Science 2025-07-16 Oliver Broadrick , Sanyam Agarwal , Guy Van den Broeck , Markus Bläser

We survey a few classes of analytic functions on the disk that have real boundary values almost everywhere on the unit circle. We explore some of their properties, various decompositions, and some connections these functions make to…

Complex Variables · Mathematics 2021-02-05 Stephan Ramon Garcia , Javad Mashreghi , William T. Ross

A rational function belongs to the Hardy space, $H^2$, of square-summable power series if and only if it is bounded in the complex unit disk. Any such rational function is necessarily analytic in a disk of radius greater than one. The…

Functional Analysis · Mathematics 2020-10-15 Michael T. Jury , Robert T. W. Martin , Eli Shamovich

In the context of the complex-analytic structure within the unit disk centered at the origin of the complex plane, that was presented in a previous paper, we show that singular Schwartz distributions can be represented within that same…

Complex Variables · Mathematics 2019-02-19 Jorge L. deLyra

Using the notions and tools from realization in the sense of systems theory, we establish an explicit and new realization formula for families of infinite products of rational matrix-functions of a single complex variable. Our realizations…

Complex Variables · Mathematics 2015-02-09 Daniel Alpay , Palle Jorgensen , Izchak Lewkowicz

This paper introduces a robust class of functions from finite words to integers that we call Z-polyregular functions. We show that it admits natural characterizations in terms of logics, Z-rational expressions, Z-rational series and…

Formal Languages and Automata Theory · Computer Science 2023-04-19 Thomas Colcombet , Gaëtan Douéneau-Tabot , Aliaume Lopez

A rational homogeneous (of degree one) positive real matrix-valued function is presented as the Schur complement of a block of the linear pencil with positive semidefinite matrix coefficients. The partial derivative numerators of a rational…

Complex Variables · Mathematics 2021-03-04 M. F. Bessmertnyi

We study Dirichlet-type spaces $\mathfrak{D}_{\alpha}$ of analytic functions in the unit bidisk and their cyclic elements. These are the functions $f$ for which there exists a sequence $(p_n)_{n=1}^{\infty}$ of polynomials in two variables…

Functional Analysis · Mathematics 2015-07-03 Catherine Bénéteau , Alberto A. Condori , Constanze Liaw , Daniel Seco , Alan A. Sola

We give a new proof that bounded non-commutative functions on polynomial polyhedra can be represented by a realization formula, a generalization of the transfer function realization formula for bounded analytic functions on the unit disk.

Functional Analysis · Mathematics 2019-08-15 Jim Agler , John E. McCarthy

In this article we examine Dirichlet type spaces in the unit polydisc, and multipliers between these spaces. These results extend the corresponding work of G. D. Taylor in the unit disc. In addition, we consider functions on the polydisc…

Functional Analysis · Mathematics 2007-05-23 Daniel Jupiter , David Redett

We prove a realization theorem for rational functions of several complex variables which extends the main theorem of M. Bessmertnyi, "On realizations of rational matrix functions of several complex variables," in Vol. 134 of Oper. Theory…

Complex Variables · Mathematics 2021-10-01 Anthony Stefan , Aaron Welters

Permutation rational functions over finite fields have attracted high interest in recent years. However, only a few of them have been exhibited. This article studies a class of permutation rational functions constructed using trace maps on…

Number Theory · Mathematics 2024-01-01 Ruikai Chen , Sihem Mesnager

Polyregular functions are the class of string-to-string functions definable by pebble transducers, an extension of finite-state automata with outputs and multiple two-way reading heads (pebbles) with a stack discipline. If a polyregular…

Formal Languages and Automata Theory · Computer Science 2023-06-21 Sandra Kiefer , Lê Thành Dũng Nguyên , Cécilia Pradic

We introduce two kinds of quasi-inner functions. Since every rationally invariant subspace for a shift operator $S_K$ on a vector-valued Hardy space $H^{2}(\Omega,K)$ is generated by a quasi-inner function, we also provide relationships of…

Functional Analysis · Mathematics 2008-01-03 Yun-Su Kim

We study factorizations of operator valued functions of weighted Schur classes over multiply-connected domains. There is a correspondence between functions from weighted Schur classes and so-called ``conservative curved'' systems introduced…

Functional Analysis · Mathematics 2007-05-23 Alexey Tikhonov

We give a controllable energy-preserving and an observable co-energy-preserving de Branges-Rovnyak functional model realization of an arbitrary given operator Schur function defined on the complex right-half plane. We work the theory out…

Optimization and Control · Mathematics 2015-11-09 Joseph A. Ball , Mikael Kurula , Olof J. Staffans , Hans Zwart