×

Herglotz functions: the Fueter variables case. (English) Zbl 07006570

Summary: In this paper we provide realizations of Herglotz functions in the quaternionic case where hyperholomorphic functions are meant in the sense of Fueter. We consider the counterparts of the Arveson space and of the Herglotz-Agler functions by introducing suitable positive kernels. Crucial tools are the so-called Fueter variables and the CK-product. Our realization results also show that positivity implies analyticity.

MSC:

47B32 Linear operators in reproducing-kernel Hilbert spaces (including de Branges, de Branges-Rovnyak, and other structured spaces)
30G35 Functions of hypercomplex variables and generalized variables
Full Text: DOI

References:

[1] Abu-Ghanem, K.; Alpay, D.; Colombo, F.; Lewkowicz, I.; Sabadini, I., Herglotz functions of several quaternionic variables, J. Math. Anal. Appl., 466, 1, 169-182 (2018) · Zbl 1393.30037
[2] Agler, J., On the representation of certain holomorphic functions defined on a polydisk, Oper. Theory Adv. Appl., vol. 48, 47-66 (1990), Birkhäuser Verlag: Birkhäuser Verlag Basel · Zbl 0733.32002
[3] Alpay, D., Some remarks on reproducing kernel Krein spaces, Rocky Mountain J. Math., 21, 1189-1205 (1991) · Zbl 0810.46025
[4] Alpay, D., An Advanced Complex Analysis Problem Book. Topological Vector Spaces, Functional Analysis, and Hilbert Spaces of Analytic Functions (2015), Birkhäuser/Springer: Birkhäuser/Springer Basel AG, Basel · Zbl 1350.46001
[5] Alpay, D.; Colombo, F.; Lewkowicz, I.; Sabadini, I., Realizations of slice hyperholomorphic generalized contractive and positive functions, Milan J. Math., 83, 91-144 (2015) · Zbl 1335.47012
[6] Alpay, D.; Colombo, F.; Sabadini, I., Inner product spaces and Krein spaces in the quaternionic setting, (Alpay, D.; Kirstein, B., Recent Advances in Inverse Scattering, Schur Analysis and Stochastic Processes. Recent Advances in Inverse Scattering, Schur Analysis and Stochastic Processes, Oper. Theory Adv. Appl., vol. 244 (2015), Birkhäuser), 33-65 · Zbl 1376.46017
[7] Alpay, D.; Dijksma, A.; Peretz, Y., Nonstationary analogs of the Herglotz representation theorem: the discrete case, J. Funct. Anal., 166, 1, 85-129 (1999) · Zbl 0984.47008
[8] Alpay, D.; Dijksma, A.; Rovnyak, J.; de Snoo, H., Schur Functions, Operator Colligations, and Reproducing Kernel Pontryagin Spaces, Oper. Theory Adv. Appl., vol. 96 (1997), Birkhäuser Verlag: Birkhäuser Verlag Basel · Zbl 0879.47006
[9] Alpay, D.; Jorgensen, P.; Lewkowicz, I., Extending wavelet filters: infinite dimensions, the nonrational case, and indefinite inner product spaces, (Excursions in Harmonic Analysis, vol. 2. Excursions in Harmonic Analysis, vol. 2, Appl. Numer. Harmon. Anal. (2013), Birkhäuser/Springer: Birkhäuser/Springer New York), 69-111 · Zbl 1311.65176
[10] Alpay, D.; Jorgensen, P.; Lewkowicz, I.; Martziano, I., Infinite product representations for kernels and iterations of functions, (Recent Advances in Inverse Scattering, Schur Analysis and Stochastic Processes. Recent Advances in Inverse Scattering, Schur Analysis and Stochastic Processes, Oper. Theory Adv. Appl., vol. 244 (2015), Birkhäuser/Springer: Birkhäuser/Springer Cham), 67-87 · Zbl 1376.46020
[11] Alpay, D.; Kaptanoğlu, H. T., Some finite-dimensional backward shift-invariant subspaces in the ball and a related interpolation problem, Integral Equations Operator Theory, 42, 1-21 (2002) · Zbl 1010.47012
[12] Alpay, D.; Shapiro, M.; Volok, D., Rational hyperholomorphic functions in \(R^4\), J. Funct. Anal., 221, 1, 122-149 (2005) · Zbl 1077.30044
[13] Alpay, D.; Shapiro, M.; Volok, D., Reproducing kernel spaces of series of Fueter polynomials, (Operator Theory in Krein Spaces and Nonlinear Eigenvalue Problems. Operator Theory in Krein Spaces and Nonlinear Eigenvalue Problems, Oper. Theory Adv. Appl., vol. 162 (2006), Birkhäuser: Birkhäuser Basel), 19-45 · Zbl 1107.46023
[14] Alpay, D.; Timoshenko, O.; Volok, D., Carathéodory functions in the Banach space setting, Linear Algebra Appl., 425, 700-713 (2007) · Zbl 1132.47009
[15] Alpay, D.; Timoshenko, O.; Volok, D., Carathéodory-Fejér interpolation and related topics in locally convex spaces, Linear Algebra Appl., 431, 1257-1266 (2009) · Zbl 1171.47012
[16] Brackx, F.; Delanghe, R.; Sommen, F., Clifford Analysis, Pitman Res. Notes Math. Ser., vol. 76 (1982) · Zbl 0529.30001
[17] Cauer, W., The realization of impedances of prescribed frequency dependence, Arch. Elektrotechnik, 17, 355-388 (1926), (in German)
[18] Cauer, W., Über Funktionen mit positivem Realteil, Math. Ann., 106, 369-394 (1932) · Zbl 0004.05001
[19] Cuntz, Joachim, Simple \(C^\ast \)-algebras generated by isometries, Comm. Math. Phys., 57, 2, 173-185 (1977) · Zbl 0399.46045
[20] Dewilde, P.; van der Veen, A.-J., Time-Varying Systems and Computations (1998), Kluwer Academic Publishers: Kluwer Academic Publishers Boston, MA · Zbl 0937.93002
[21] Dijksma, A.; Langer, H.; de Snoo, H. S.V., Representations of holomorphic operator functions by means of resolvents of unitary or selfadjoint operators in Kreĭn spaces, (Operators in Indefinite Metric Spaces, Scattering Theory and Other Topics. Operators in Indefinite Metric Spaces, Scattering Theory and Other Topics, Bucharest, 1985. Operators in Indefinite Metric Spaces, Scattering Theory and Other Topics. Operators in Indefinite Metric Spaces, Scattering Theory and Other Topics, Bucharest, 1985, Oper. Theory Adv. Appl., vol. 24 (1987), Birkhäuser: Birkhäuser Basel), 123-143 · Zbl 0625.47010
[22] Donoghue, W. F., Monotone Matrix Functions and Analytic Continuation, Die Grundlehren der mathematischen Wissennschaften, vol. 207 (1974), Springer-Verlag · Zbl 0278.30004
[23] Fueter, R., Analytische Funktionen einer Quaternionenvariablen, Comment. Math. Helv., 4, 9-20 (1932) · JFM 58.0144.05
[24] Gheondea, A., Reproducing kernel Kreĭn spaces, (Alpay, D., Operator Theory (2015), Springer: Springer Basel), 311-343, with 51 figures and 2 tables, in 2 volumes · Zbl 1347.46020
[25] Jury, M. T., Operator-valued Herglotz kernels and functions of positive real part on the ball, Complex Anal. Oper. Theory, 4, 2, 301-317 (2010) · Zbl 1206.32002
[26] Knese, G., Rational inner functions in the Schur-Agler class of the polydisk, Publ. Mat., 55, 2, 343-357 (2011) · Zbl 1219.47028
[27] McCarthy, J.; Putinar, M., Positivity aspects of the Fantappiè transform, J. Anal. Math., 97, 57-82 (2005) · Zbl 1132.46017
[28] Moisil, Gr. C., Sur les quaternions monogènes, Bull. Sci. Math. (Paris), LV, 168-174 (1931) · Zbl 0002.19402
[29] Popescu, G., Free holomorphic functions and interpolation, Math. Ann., 342, 1, 1-30 (2008) · Zbl 1146.47010
[30] Rudin, W., Function Theory in the Unit Ball of \(C^n (1980)\), Springer-Verlag · Zbl 0495.32001
[31] Sommen, F., A product and an exponential function in hypercomplex function theory, Appl. Anal., 12, 1, 13-26 (1981) · Zbl 0454.30039
[32] Springer, T. A., Linear Algebraic Groups, Progr. Math., vol. 9 (1981), Birkhäuser: Birkhäuser Boston, Mass · Zbl 0453.14022
[33] Zhang, F., Quaternions and matrices of quaternions, Linear Algebra Appl., 251, 21-57 (1997) · Zbl 0873.15008
This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. In some cases that data have been complemented/enhanced by data from zbMATH Open. This attempts to reflect the references listed in the original paper as accurately as possible without claiming completeness or a perfect matching.