Abstract
In this article, we extend the recently developed abstract theory of universal series to include averaged sums of the form \({\frac{1}{\phi(n)}\sum_{j=0}^{n} a_j x_j}\) for a given fixed sequence of vectors (x j ) in a topological vector space X over a field \({\mathbb{K}}\) of real or complex scalars, where \({(\phi(n))}\) is a sequence of non-zero field scalars. We give necessary and sufficient conditions for the existence of a sequence of coefficients (a j ) which make the above sequence of averaged sums dense in X. When applied, the extended theory gives new analogues to well known classical theorems including those of Seleznev, Fekete and Menchoff.
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References
Armitage D.H.: Universal overconvergence of polynomial expansions of harmonic functions. J. Approx. Theory 118, 225–234 (2002)
Armitage, D.H.: Dense vector spaces of universal harmonic functions. In: Advances in Multivariate Approximation (Witten-Bommerholz 1998), pp. 33–42 (1999)
Armitage D.H., Gauthier P.M.: Recent developments in harmonic approximation, with applications. Results Math. 29, 1–15 (1996)
Bagchi, B.: The Statistical Behaviour and Universality Properties of the Riemann Zeta Function and other Allied Dirichlet Series. Thesis, Indian Statistical Institute, Calcutta (1981)
Bagchi B.: A joint universality theorem for Dirichlet L-functions. Math. Z. 181, 319–334 (1982)
Bayart F.: Topological and algebraic genericity of divergence and universality. Studia Math. 167, 161–181 (2005)
Bayart F., Grosse-Erdmann K.-G., Nestoridis V., Papadimitropoulos C.: Abstract theory of universal series and applications. Proc. Lond. Math. Soc. (3) 96, 417–463 (2008)
Bernal-González L.: Densely hereditarily hypercyclic sequences and large hypercyclic manifolds. Proc. Am. Math. Soc. 127, 3279–3285 (1999)
Bernal-González L., Calderón-Moreno M.C.: Dense linear manifolds of monsters. J. Approx. Theory 119, 156–180 (2002)
Bernal-González L., Montes-Rodríguez A.: Non-finite dimensional closed vector spaces of universal functions for composition operators. J. Approx. Theory 82, 375–391 (1995)
Bourdon P.S.: Invariant manifolds of hypercyclic vectors. Proc. Am. Math. Soc. 118, 845–847 (1993)
Čaščina N.S.: On the theory of a universal Dirichlet series (Russian). Izv. Vyssh Uchebn Zaved Mat. 35, 165–167 (1963)
Costakis G., Hadjiloucas D.: Somewhere dense Cesàro orbits and rotations of Cesàro hypercyclic operators. Studia Math. 175, 249–269 (2006)
Gardiner, S.J.: Harmonic Approximation. LMS Lecture Note Series, vol. 221, CUP (1995)
Grosse-Erdmann K.-G.: Universal families and hypercyclic operators. Bull. Am. Math. Soc. (New Series) 36, 345–381 (1999)
Kahane J.-P.: Baire’s category theorem and trigonometric series. J. d’Analyse Math. 80, 143–182 (2000)
Koumoullis G., Luh W., Nestoridis V.: Universal functions are automatically universal in the sense of Menchoff. Complex Variables Elliptic Equ. 52, 307–314 (2007)
León-Saavedra F., Montes-Rodríguez A.: Linear structure of hypercyclic vectors. J. Func. Anal. 148, 524–545 (1997)
León-Saavedra F., Montes-Rodríguez A.: Spectral theory and hypercyclic subspaces. Trans. Am. Math. Soc. 353, 247–267 (2001)
Melas A., Nestoridis V.: Universality of Taylor series as a generic property of holomorphic functions. Adv. Math. 157, 138–176 (2001)
Menchoff D.: Sur les séries trigonométriques universelles. C. R. (Dokl) Acad. Sci. URSS (NS) 49, 79–82 (1945)
Menchoff D.: On the convergence in measure of trigonometric series (Russian). Dokl. Akad. Nauk. SSSR (NS) 59, 849–852 (1948)
Menchoff, D.E.: On convergence in measure of trigonometric series (Russian). Trudy Mat. Inst. Steklov. 32 (1950), English transl in: Am. Math. Soc. Transl. (1) 3, 196–270 (1962)
Menchoff, D.: On universal sequences of functions (Russian). Dokl. Akad. Nauk. SSSR 151, 1283–1285 (1963), English transl in: Sov. Math. Dokl. 4, 1191–1193 (1963)
Menchoff, D.E.: Universal sequences of functions (Russian). Mat. Sb (NS) 65(107), 272–312 (1964), English transl in: Am. Math. Soc. Transl. (2) 111, 81–116 (1978)
Montes-Rodríguez A.: Banach spaces of hypercyclic vectors. Michigan Math. J. 43, 419–436 (1996)
Montes-Rodríguez, A.: Vector spaces of universal functions. In: Complex Methods in Approximation Theory (Proc Workshop, Almería, 1995), pp. 113–116 (1997)
Nestoridis V.: Universal Taylor series. Ann. Inst. Fourier 46, 1293–1306 (1996)
Nestoridis V., Papadimitropoulos C.: Abstract theory of universal series and an application to Dirichlet series. C. R. Math. Acad. Sci. Paris 341, 539–543 (2005)
Pál J.: Zwei kleine Bemerkungen. Tôhoku Math. J. 6, 42–43 (1914/15)
Papadimitropoulos, C.: Specific Types of Universal Series in Classical Mathematical Analysis (Greek). Master Thesis, University of Athens (2006)
Seleznev A.I.: On universal power series (Russian). Mat. Sb (NS) 28(70), 453–460 (1951)
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Hadjiloucas, D. Extended abstract theory of universal series and applications. Monatsh Math 158, 151–178 (2009). https://doi.org/10.1007/s00605-008-0038-2
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DOI: https://doi.org/10.1007/s00605-008-0038-2
Keywords
- Universal series
- Cesàro hypercyclicity
- Dirichlet series
- Menchoff’s theorem
- Seleznev’s theorem
- Fekete’s theorem