Abstract
A locally compact group G is compact if and only if its convolution algebra has a non-zero (weakly) compact multiplier. Dually, G is discrete if and only if its Fourier algebra has a non-zero (weakly) compact multiplier. In addition, G is compact (respectively, amenable) if and only if the second dual of its convolution algebra equipped with the first Arens product has a non-zero (weakly) compact left (respectively, right) multiplier. We prove the non-commutative versions of these results in the case of locally compact quantum groups.
Similar content being viewed by others
References
Aiena, P.: Fredholm and Local Spectral Theory, with Application to Multipliers. Kluwer Academic Publishers, Dordrecht (2004)
Amini, M., Kalantar, M., Medghalchi, A., Mollakhalili, A., Neufang, M.: Compact elements and operators of quantum groups. Glasgow Math. J. 59(2), 445–462 (2017). https://doi.org/10.1017/S0017089516000276
Baaj, S., Skandalis, G., Vaes, S.: Non-semi-regular quantum groups coming from number theory. Commun. Math. Phys. 235(1), 139–167 (2003)
Baker, J., Lau, A.T.-M., Pym, J.S.: Module homomorphisms and topological centers associated with weakly sequentially complete Banach algebras. J. Funct. Anal. 158(1), 186–208 (1998)
Bartle, R., Dunford, N., Schwartz, J.: Weak compactness and vector measures. Can. J. Math. 7, 289–305 (1955)
Bedos, E., Tuset, L.: Amenability and co-amenability for locally compact quantum groups. Int. J. Math. 14(8), 865–884 (2003)
Berglund, J.F., Junghenn, H.D., Milnes, P.: Analysis on semigroups. Function spaces, compactifications, representations. In: Canadian Mathematical Society Series of Monographs and Advanced Texts. Wiley, New York (1989)
Bonsall, F.F., Duncan, J.: Complete Normed Algebras. Springer, New York (1973)
Brešar, M., Eremita, D.: The lower socle and finite rank elementary operators. Commun. Algebra 31(3), 1485–1497 (2003)
Brešar, M., Turovskii, Y.V.: Compactness conditions for elementary operators. Stud. Math. 178(1), 1–18 (2007)
Brešar, M.: On the distance of the composition of two derivations to the generalized derivations. Glasgow Math. J. 33(1), 89–93 (1991)
Crann, J., Neufang, M.: Amenability and covariant injectivity of locally compact quantum groups. Trans. Am. Math. Soc. 368(1), 495–513 (2016)
Dalla, L., Giotopoulos, S., Katseli, N.: The socle and finite-dimensionality of a semiprime Banach algebra. Stud. Math. 92(2), 201–204 (1989)
Dales, H.G.: Banach Algebras and Automatic Continuity, London Mathematical Society Monographs. New Series, vol. 24. Oxford University Press, New York (2000)
Dales, H.G., Lau, A.T.-M.: The second duals of Beurling algebras. Mem. Am. Math. Soc. 177(836), vi+191 (2005)
Daws, M.: Completely positive multipliers of quantum groups. Int. J. Math. 23(12), 1250132 (2012)
Daws, M.: Multipliers of locally compact quantum groups via Hilbert C\(^*\)-modules. J. Lond. Math. Soc. (2) 84(2), 385–407 (2011)
Daws, M.: Multipliers, self-induced and dual Banach algebras. Dissertationes Math. 470, 62 (2010)
Daws, M.: Remarks on the quantum Bohr compactification. Ill. J. Math. 57(4), 1131–1171 (2013)
Daws, M., Pham, L.H.: Isometries between quantum convolotion algebras. Q. J. Math. 64(2), 373–396 (2013)
Daws, M., Salmi, P.: Completely positive definite functions and Bochner’s theorem for locally compact quantum groups. J. Funct. Anal. 264(7), 1525–1546 (2013)
Desmedt, P., Quaegebeur, J., Vaes, S.: Amenability and the bicrossed product construction. Ill. J. Math. 46(4), 1259–1277 (2002)
Diestel, J., Faires, B.: On vector measures. Trans. Am. Math. Soc. 198, 253–271 (1974)
Dunford, N., Schwartz, J.T.: Linear Operators, I: General Theory, Pure and Applied Mathematics, vol. 7. Interscience, New York (1958)
Enock, M., Schwartz, J.M.: Kac Algebras and Duality of Locally Compact Groups. Springer, Berlin (1992)
Erdos, J.A.: On certain elements of \(C^*\)-algebras. Ill. J. Math. 15, 682–693 (1971)
Eshaghi Gordji, M., Hosseiniun, S.A.R.: The fourth dual of Banach algebras. Ital. J. Pure Appl. Math. 24, 53–60 (2007)
Eymard, P.: L’ alg\({\mathbb{G}}rave{e}\)bre de Fourier d’un groupe localement compact. Bull. Soc. Math. France 92(8), 181–236 (1964)
Filali, M.: Finite-dimensional left ideals in some algebras associated with a locally compact group. Proc. Am. Math. Soc. 127, 2325–2333 (1999)
Fima, P.: On locally compact quantum groups whose algebras are factors. J. Funct. Anal. 244(1), 78–94 (2007)
Folland, G.B.: A Course in Abstract Harmonic Analysis. CRC Press, Boca Raton (2016)
Forrest, B.: Arens regularity and discrete groups. Pac. J. Math. 151(2), 217–227 (1991)
Ghaffari, A.: Module homomorphisms associated with Banach algebras. Taiwan. J. Math. 15(3), 1075–1088 (2011)
Ghaffari, A., Medghalchi, A.: The Socle and finite dimensionality of some Banach algebras. Proc. Indian Acad. Sci. Math. Sci. 115(3), 327–330 (2005)
Ghahramani, F., Lau, A.T.: Isomorphisms and multipliers on second dual algebras of Banach algebras. Math. Proc. Camb. Philos. Soc. 111(1), 161–168 (1992)
Ghahramani, F., Lau, A.T.: Multipliers and ideals in second conjugate algebras related to locally compact groups. J. Funct. Anal. 132(1), 170–191 (1995)
Ghahramani, F., Loy, R.J., Willis, G.A.: Amenability and weak amenability of second conjugate Banach algebras. Proc. Am. Math. Soc. 124(5), 1489–1497 (1996)
Hu, Z., Monfared, M.S., Traynor, T.: On character amenable Banach algebra. Stud. Math. 193(1), 53–78 (2009)
Hu, Z., Neufang, M., Ruan, Z.-J.: Completely bounded multipliers over locally compact quantum groups. Proc. Lond. Math. Soc. (3) 103(1), 1–39 (2011)
Hu, Z., Neufang, M., Ruan, Z.-J.: Module maps over locally compact quantum groups. Stud. Math. 211(2), 111–145 (2012)
Hu, Z., Neufang, M., Ruan, Z.-J.: Multipliers on a new class of Banach algebras, locally compact quantum groups, and topological centres. Proc. Lond. Math. Soc. (3) 100(2), 429–458 (2010)
Hu, Z., Neufang, M., Ruan, Z.-J.: On topological centre problems and SIN quantum groups. J. Funct. Anal. 257(2), 610–640 (2009)
Junge, M., Neufang, M., Ruan, Z.-J.: A representation theorem for locally compact quantum groups. Int. J. Math. 20(3), 377–400 (2009)
Kalantar, M.: Compact operators in regular LCQ groups. Can. Math. Bull. 57(3), 546–550 (2014)
Kalantar, M.: Towards harmonic analysis on locally compact quantum groups from groups to quantum groups and back. Ph.D. thesis, Carleton University (Canada), ProQuest LLC, Ann Arbor, MI (2011)
Kaniuth, E., Lau, A.T.-M., Pym, J.: On character amenability of Banach algebras. J. Math. Anal. Appl. 344(2), 942–955 (2008)
Kaplanski, I.: The structure of certain operator algebras. Trans. Am. Math. Soc. 70, 219–255 (1951)
Kustermans, J.: Locally compact quantum groups in the universal setting. Int. J. Math. 12(3), 289–338 (2001)
Kustermans, J., Vaes, S.: Locally compact quantum groups. Ann. Sci. Èole Norm. Sup. (4) 33(6), 837–934 (2000)
Kustermans, J., Vaes, S.: Locally compact quantum groups in the von Neumann algebraic setting. Math. Scand. 92(1), 68–92 (2003)
Lau, A.T.-M.: The second conjugate algebra of the Fourier algebra of a locally compact group. Trans. Am. Math. Soc. 267(1), 53–63 (1981)
Lau, A.T.-M.: Uniformly continuous functionals on the Fourier algebra of any locally compact group. Trans. Am. Math. Soc. 251, 39–59 (1979)
Lau, A.T.-M., Losert, V.: On the second conjugate algebra of \(L^1(G)\) of a locally compact group. J. Lond. Math. Soc. (2) 37(3), 464–470 (1988)
Lau, A.T.-M., Losert, V.: The centre of the second conjugate algebra of the Fourier algebra for infinite products of groups. Math. Proc. Camb. Philos. Soc. 138(1), 27–39 (2005)
Lau, A.T.-M., Ülger, A.: Topological centers of certain dual algebras. Trans. Am. Math. Soc. 348(3), 1191–1212 (1996)
Lee, T.-K., Wong, T.-L.: Semiprime algebras with finiteness conditions. Commun. Algebra 31(4), 1823–1835 (2003)
Losert, V.: The centre of the bidual of Fourier algebras (discrete groups) (preprint) (2002)
Losert, V.: Weakly compact multipliers on group algebras. J. Funct. Anal. 213(2), 466–472 (2004)
Mewomo, O.T., Maepa, S.M.: On character amenability of Beurling and second dual algebras. Acta Univ. Apulensis Math. Inform. 38, 67–80 (2014)
Monfared, M.S.: Character amenability of Banach algebras. Math. Proc. Camb. Philos. Soc. 144(3), 697–706 (2008)
Murphy, G.J.: \(C^*\)-Algebras and Operator Theory. Academic Press Inc., Boston (1990)
Olubummo, A.: Weakly compact B\(^\sharp \)-algebras. Proc. Am. Math. Soc. 14, 905–908 (1963)
Ramezanpour, M., Vishki, H.R.E.: Module homomorphisms and multipliers on locally compact quantum groups. J. Math. Anal. Appl. 359(2), 581–587 (2009)
Ruan, Z.-J.: Amenability of Hopf von Neumann algebras and Kac algebras. J. Funct. Anal. 139(2), 466–499 (1996)
Runde, V.: Characterizations of compact and discrete quantum groups through second duals. J. Oper. Theory 60(2), 415–428 (2008)
Runde, V.: Uniform continuity over locally compact quantum groups. J. Lond. Math. Soc. (2) 80(1), 55–71 (2009)
Sakai, S.: Weakly compact operators on operator algebras. Pac.J. Math. 14, 659–664 (1964)
Sołtan, P.M.: Quantum Bohr compactification. Ill. J. Math. 49(4), 1245–1270 (2005)
Takesaki, M.: Theory of Operator Algebras, I. Springer, New York (1979)
Taylor, K.F.: Geometry of the Fourier algebras and locally compact groups with atomic unitary representations. Math. Ann. 262(2), 183–190 (1983)
Tomiuk, B.J.: Arens regularity and the algebra of double multipliers. Proc. Am. Math. Soc. 81(2), 293–298 (1981)
Tomiuk, B.J.: Topological algebras with dense socle. J. Funct. Anal. 28(2), 254–277 (1978)
Ülger, A.: Arens regularity of weakly sequentially complete Banach algebras. Proc. Am. Math. Soc. 127(11), 3221–3227 (1999)
Vaes, S.: Locally compact quantum groups. Ph.D. Thesis, KU Leuven (2001)
Vakilabad, A.B., Haghnejad Azar, K., Jabbari, A.: Arens regularity of module actions and weak amenability of Banach algebras. Period. Math. Hung. 71(2), 224–235 (2015)
Van Daele, A.: Locally compact quantum groups. A von Neumann algebra approach. SIGMA Symmetry Integr. Geom. Methods Appl. 10, 41 (2014). (paper 082)
Wright, J.D.M., Ylinen, K.: Multilinear maps on products of operator algebras. J. Math. Anal. Appl. 292(2), 558–570 (2004)
Wong, P.K.: On the Arens product and annihilator algebras. Proc. Am. Math. Soc. 30, 79–83 (1971)
Ylinen, K.: Weakly completely continuous elements of \(C^*\)-algebras. Proc. Am. Math. Soc. 52, 323–326 (1975)
Young, N.J.: The irregularity of multiplication in group algebras. Q. J. Math. Oxf. Ser. (2) 24, 59–62 (1973)
Author information
Authors and Affiliations
Corresponding author
Additional information
Communicated by Massoud Amini.
Rights and permissions
About this article
Cite this article
Medghalchi, A., Mollakhalili, A. Compact and Weakly Compact Multipliers of Locally Compact Quantum Groups. Bull. Iran. Math. Soc. 44, 101–136 (2018). https://doi.org/10.1007/s41980-018-0008-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s41980-018-0008-y