AMS eBook CollectionsOne of the world's most respected mathematical collections, available in digital format for your library or institution
Banach algebras on semigroups and on their compactifications
About this Title
H. G. Dales, Department of Pure Mathematics, University of Leeds, Leeds LS2 9JT, United Kingdom, A. T.-M. Lau, Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, Alberta T6G 2G1, Canada and D. Strauss, Department of Pure Mathematics, University of Leeds, Leeds LS2 9JT, United Kingdom
Publication: Memoirs of the American Mathematical Society
Publication Year:
2010; Volume 205, Number 966
ISBNs: 978-0-8218-4775-6 (print); 978-1-4704-0580-9 (online)
DOI: https://doi.org/10.1090/S0065-9266-10-00595-8
Published electronically: January 25, 2010
Keywords: Banach algebras,
second duals,
dual Banach algebras,
Arens products,
Arens regular,
topological centre,
strongly Arens irregular,
introverted subspace,
amenable,
weakly amenable,
approximately amenable,
amenability constant,
ultrafilter,
Stone–Čech compactification,
invariant mean,
semigroup,
Rees semigroup,
semigroup algebra,
Munn algebra,
semi-character,
character,
cancellative semigroup,
radical,
minimal ideal,
idempotent,
locally compact group,
group algebra,
measure algebra,
bounded approximate identity,
diagonal
MSC: Primary 43A10, 43A20; Secondary 46J10
Table of Contents
Chapters
- 1. Introduction
- 2. Banach algebras and their second duals
- 3. Semigroups
- 4. Semigroup algebras
- 5. Stone–Čech compactifications
- 6. The semigroup $(\beta S, \Box )$
- 7. Second duals of semigroup algebras
- 8. Related spaces and compactifications
- 9. Amenability for semigroups
- 10. Amenability of semigroup algebras
- 11. Amenability and weak amenability for certain Banach algebras
- 12. Topological centres
- 13. Open problems
Abstract
Let $S$ be a (discrete) semigroup, and let $\ell ^{\,1}( S )$ be the Banach algebra which is the semigroup algebra of $S$. We shall study the structure of this Banach algebra and of its second dual.
We shall determine exactly when $\ell ^{\,1}( S )$ is amenable as a Banach algebra, and shall discuss its amenability constant, showing that there are ‘forbidden values’ for this constant.
The second dual of $\ell ^{\,1}( S )$ is the Banach algebra $M(\beta S)$ of measures on the Stone–Čech compactification $\beta S$ of $S$, where $M(\beta S)$ and $\beta S$ are taken with the first Arens product $\Box$. We shall show that $S$ is finite whenever $M(\beta S)$ is amenable, and we shall discuss when $M(\beta S)$ is weakly amenable. We shall show that the second dual of $L^1(G)$, for $G$ a locally compact group, is weakly amenable if and only if $G$ is finite.
We shall also discuss left-invariant means on $S$ as elements of the space $M(\beta S)$, and determine their supports.
We shall show that, for each weakly cancellative and nearly right cancellative semigroup $S$, the topological centre of $M(\beta S)$ is just $\ell ^{\,1}(S)$, and so $\ell ^{\,1}(S)$ is strongly Arens irregular; indeed, we shall considerably strengthen this result by showing that, for such semigroups $S$, there are two-element subsets of $\beta S \setminus S$ that are determining for the topological centre; for more general semigroups $S$, there are finite subsets of $\beta S \setminus S$ with this property.
We have partial results on the radical of the algebras $\ell ^{\,1}(\beta S )$ and $M(\beta S)$.
We shall also discuss analogous results for related spaces such as $WAP(S)$ and $LUC(G)$.
- P. D. Adams, Algebraic topics in the Stone–Čech compactifications of semigroups, Thesis, University of Hull, 2001.
- Richard Arens, Operations induced in function classes, Monatsh. Math. 55 (1951), 1–19. MR 44109, DOI 10.1007/BF01300644
- Richard Arens, The adjoint of a bilinear operation, Proc. Amer. Math. Soc. 2 (1951), 839–848. MR 45941, DOI 10.1090/S0002-9939-1951-0045941-1
- J. W. Baker and Ali Rejali, On the Arens regularity of weighted convolution algebras, J. London Math. Soc. (2) 40 (1989), no. 3, 535–546. MR 1053620, DOI 10.1112/jlms/s2-40.3.535
- M. Lashkarizadeh Bami, The topological centers of $LUC(S)^*$ and $M_a(S)^{**}$ of certain foundation semigroups, Glasg. Math. J. 42 (2000), no. 3, 335–343. MR 1793802, DOI 10.1017/S0017089500030020
- B. A. Barnes and J. Duncan, The Banach algebra $l^{1}(S)$, J. Functional Analysis 18 (1975), 96–113. MR 377415, DOI 10.1016/0022-1236(75)90032-4
- Mathias Beiglböck, Vitaly Bergelson, Neil Hindman, and Dona Strauss, Multiplicative structures in additively large sets, J. Combin. Theory Ser. A 113 (2006), no. 7, 1219–1242. MR 2259058, DOI 10.1016/j.jcta.2005.11.003
- Christian Berg, Jens Peter Reus Christensen, and Paul Ressel, Positive definite functions on abelian semigroups, Math. Ann. 223 (1976), no. 3, 253–274. MR 420150, DOI 10.1007/BF01360957
- Christian Berg, Jens Peter Reus Christensen, and Paul Ressel, Harmonic analysis on semigroups, Graduate Texts in Mathematics, vol. 100, Springer-Verlag, New York, 1984. Theory of positive definite and related functions. MR 747302, DOI 10.1007/978-1-4612-1128-0
- John F. Berglund, Hugo D. Junghenn, and Paul Milnes, Analysis on semigroups, Canadian Mathematical Society Series of Monographs and Advanced Texts, John Wiley & Sons, Inc., New York, 1989. Function spaces, compactifications, representations; A Wiley-Interscience Publication. MR 999922
- T. D. Blackmore, Weak amenability of discrete semigroup algebras, Semigroup Forum 55 (1997), no. 2, 196–205. MR 1457765, DOI 10.1007/PL00005921
- David P. Blecher, Are operator algebras Banach algebras?, Banach algebras and their applications, Contemp. Math., vol. 363, Amer. Math. Soc., Providence, RI, 2004, pp. 53–58. MR 2097949, DOI 10.1090/conm/363/06640
- Shea D. Burns, The existence of disjoint smallest ideals in the two natural products on $\beta S$, Semigroup Forum 63 (2001), no. 2, 191–201. MR 1830683, DOI 10.1007/s002330010019
- R. J. Butcher, Thesis, University of Sheffield, 1975.
- Timothy J. Carlson, Neil Hindman, Jillian McLeod, and Dona Strauss, Almost disjoint large subsets of semigroups, Topology Appl. 155 (2008), no. 5, 433–444. MR 2380928, DOI 10.1016/j.topol.2005.05.012
- Paul Civin and Bertram Yood, The second conjugate space of a Banach algebra as an algebra, Pacific J. Math. 11 (1961), 847–870. MR 143056
- A. H. Clifford and G. B. Preston, The algebraic theory of semigroups. Vol. I, Mathematical Surveys, No. 7, American Mathematical Society, Providence, R.I., 1961. MR 0132791
- W. W. Comfort and S. Negrepontis, The theory of ultrafilters, Die Grundlehren der mathematischen Wissenschaften, Band 211, Springer-Verlag, New York-Heidelberg, 1974. MR 0396267
- H. G. Dales, Banach algebras and automatic continuity, London Mathematical Society Monographs. New Series, vol. 24, The Clarendon Press, Oxford University Press, New York, 2000. Oxford Science Publications. MR 1816726
- H. G. Dales and H. V. Dedania, Weighted convolution algebras on subsemigroups of the real line, Dissertationes Math. 459 (2009), 60. MR 2477218, DOI 10.4064/dm459-0-1
- H. G. Dales and A. T.-M. Lau, The second duals of Beurling algebras, Mem. Amer. Math. Soc. 177 (2005), no. 836, vi+191. MR 2155972, DOI 10.1090/memo/0836
- H. G. Dales and W. H. Woodin, An introduction to independence for analysts, London Mathematical Society Lecture Note Series, vol. 115, Cambridge University Press, Cambridge, 1987. MR 942216, DOI 10.1017/CBO9780511662256
- H. G. Dales, F. Ghahramani, and A. Ya. Helemskii, The amenability of measure algebras, J. London Math. Soc. (2) 66 (2002), no. 1, 213–226. MR 1911870, DOI 10.1112/S0024610702003381
- H. G. Dales, A. T.-M. Lau, and D. Strauss, Second duals of measure algebras, Dissertationes Math., submitted.
- H. G. Dales, Niels Jakob Laustsen, and Charles J. Read, A properly infinite Banach $\ast$-algebra with a non-zero, bounded trace, Studia Math. 155 (2003), no. 2, 107–129. MR 1961188, DOI 10.4064/sm155-2-2
- H. G. Dales, R. J. Loy, and Y. Zhang, Approximate amenability for Banach sequence algebras, Studia Math. 177 (2006), no. 1, 81–96. MR 2283709, DOI 10.4064/sm177-1-6
- H. G. Dales, A. Rodríguez-Palacios, and M. V. Velasco, The second transpose of a derivation, J. London Math. Soc. (2) 64 (2001), no. 3, 707–721. MR 1865558, DOI 10.1112/S0024610701002496
- Matthew Daws, Dual Banach algebras: representations and injectivity, Studia Math. 178 (2007), no. 3, 231–275. MR 2289356, DOI 10.4064/sm178-3-3
- Mahlon M. Day, Amenable semigroups, Illinois J. Math. 1 (1957), 509–544. MR 92128
- M. Despić and F. Ghahramani, Weak amenability of group algebras of locally compact groups, Canad. Math. Bull. 37 (1994), no. 2, 165–167. MR 1275699, DOI 10.4153/CMB-1994-024-4
- J. Duncan and S. A. R. Hosseiniun, The second dual of a Banach algebra, Proc. Roy. Soc. Edinburgh Sect. A 84 (1979), no. 3-4, 309–325. MR 559675, DOI 10.1017/S0308210500017170
- J. Duncan and I. Namioka, Amenability of inverse semigroups and their semigroup algebras, Proc. Roy. Soc. Edinburgh Sect. A 80 (1978), no. 3-4, 309–321. MR 516230, DOI 10.1017/S0308210500010313
- J. Duncan and A. L. T. Paterson, Amenability for discrete convolution semigroup algebras, Math. Scand. 66 (1990), no. 1, 141–146. MR 1060904, DOI 10.7146/math.scand.a-12298
- Charles F. Dunkl and Donald E. Ramirez, Weakly almost periodic functionals on the Fourier algebra, Trans. Amer. Math. Soc. 185 (1973), 501–514. MR 372531, DOI 10.1090/S0002-9947-1973-0372531-2
- Charles F. Dunkl and Donald E. Ramirez, Representations of commutative semitopological semigroups, Lecture Notes in Mathematics, Vol. 435, Springer-Verlag, Berlin-New York, 1975. MR 0463348
- M. Eshaghi Gordji and M. Filali, Weak amenability of the second dual of a Banach algebra, Studia Math. 182 (2007), no. 3, 205–213. MR 2360627, DOI 10.4064/sm182-3-2
- G. H. Esslamzadeh, Banach algebra structure and amenability of a class of matrix algebras with applications, J. Funct. Anal. 161 (1999), no. 2, 364–383. MR 1674619, DOI 10.1006/jfan.1998.3251
- G. H. Esslamzadeh, Duals and topological center of a class of matrix algebras with applications, Proc. Amer. Math. Soc. 128 (2000), no. 12, 3493–3503. MR 1694860, DOI 10.1090/S0002-9939-00-05521-0
- Pierre Eymard, L’algèbre de Fourier d’un groupe localement compact, Bull. Soc. Math. France 92 (1964), 181–236 (French). MR 228628
- Lonnie Fairchild, Extreme invariant means without minimal support, Trans. Amer. Math. Soc. 172 (1972), 83–93. MR 308685, DOI 10.1090/S0002-9947-1972-0308685-2
- Stefano Ferri and Matthias Neufang, On the topological centre of the algebra $\textrm {LUC}(\scr G)^\ast$ for general topological groups, J. Funct. Anal. 244 (2007), no. 1, 154–171. MR 2294480, DOI 10.1016/j.jfa.2006.11.011
- S. Ferri and D. Strauss, Ideals, idempotents and right cancelable elements in the uniform compactification, Semigroup Forum 63 (2001), no. 3, 449–456. MR 1851824, DOI 10.1007/s002330010074
- S. Ferri and D. Strauss, A note on the $\scr {WAP}$-compactification and the $\scr {LUC}$-compactification of a topological group, Semigroup Forum 69 (2004), no. 1, 87–101. MR 2063981, DOI 10.1007/s00233-003-0026-8
- M. Filali, Finite-dimensional right ideals in some algebras associated with a locally compact group, Proc. Amer. Math. Soc. 127 (1999), no. 6, 1729–1734. MR 1473666, DOI 10.1090/S0002-9939-99-04631-6
- Mahmoud Filali and Pekka Salmi, Slowly oscillating functions in semigroup compactifications and convolution algebras, J. Funct. Anal. 250 (2007), no. 1, 144–166. MR 2345910, DOI 10.1016/j.jfa.2007.05.004
- Mahmoud Filali and Ajit Iqbal Singh, Recent developments on Arens regularity and ideal structure of the second dual of a group algebra and some related topological algebras, General topological algebras (Tartu, 1999) Math. Stud. (Tartu), vol. 1, Est. Math. Soc., Tartu, 2001, pp. 95–124. MR 1853838
- Brian Forrest, Weak amenability and the second dual of the Fourier algebra, Proc. Amer. Math. Soc. 125 (1997), no. 8, 2373–2378. MR 1389517, DOI 10.1090/S0002-9939-97-03844-6
- Brian E. Forrest and Volker Runde, Amenability and weak amenability of the Fourier algebra, Math. Z. 250 (2005), no. 4, 731–744. MR 2180372, DOI 10.1007/s00209-005-0772-2
- F. Ghahramani and J. Laali, Amenability and topological centres of the second duals of Banach algebras, Bull. Austral. Math. Soc. 65 (2002), no. 2, 191–197. MR 1898533, DOI 10.1017/S0004972700020232
- Fereidoun Ghahramani and Anthony To Ming Lau, Multipliers and ideals in second conjugate algebras related to locally compact groups, J. Funct. Anal. 132 (1995), no. 1, 170–191. MR 1346222, DOI 10.1006/jfan.1995.1104
- F. Ghahramani and R. J. Loy, Generalized notions of amenability, J. Funct. Anal. 208 (2004), no. 1, 229–260. MR 2034298, DOI 10.1016/S0022-1236(03)00214-3
- F. Ghahramani and J. P. McClure, Module homomorphisms of the dual modules of convolution Banach algebras, Canad. Math. Bull. 35 (1992), no. 2, 180–185. MR 1165166, DOI 10.4153/CMB-1992-026-8
- F. Ghahramani, A. T. Lau, and V. Losert, Isometric isomorphisms between Banach algebras related to locally compact groups, Trans. Amer. Math. Soc. 321 (1990), no. 1, 273–283. MR 1005079, DOI 10.1090/S0002-9947-1990-1005079-2
- F. Ghahramani, R. J. Loy, and G. A. Willis, Amenability and weak amenability of second conjugate Banach algebras, Proc. Amer. Math. Soc. 124 (1996), no. 5, 1489–1497. MR 1307520, DOI 10.1090/S0002-9939-96-03177-2
- F. Ghahramani, R. J. Loy, and Y. Zhang, Generalized notions of amenability. II, J. Funct. Anal. 254 (2008), no. 7, 1776–1810. MR 2397875, DOI 10.1016/j.jfa.2007.12.011
- Mahya Ghandehari, Hamed Hatami, and Nico Spronk, Amenability constants for semilattice algebras, Semigroup Forum 79 (2009), no. 2, 279–297. MR 2538726, DOI 10.1007/s00233-008-9115-z
- Leonard Gillman and Meyer Jerison, Rings of continuous functions, The University Series in Higher Mathematics, D. Van Nostrand Co., Inc., Princeton, N.J.-Toronto-London-New York, 1960. MR 0116199
- Irving Glicksberg, Uniform boundedness for groups, Canadian J. Math. 14 (1962), 269–276. MR 155923, DOI 10.4153/CJM-1962-017-3
- Frédéric Gourdeau, Amenability and the second dual of a Banach algebra, Studia Math. 125 (1997), no. 1, 75–81. MR 1455624, DOI 10.4064/sm-125-1-75-81
- E. Granirer, On amenable semigroups with a finite-dimensional set of invariant means. I, Illinois J. Math. 7 (1963), 32–48. MR 144197
- E. Granirer, Extremely amenable semigroups, Math. Scand. 17 (1965), 177–197. MR 197595, DOI 10.7146/math.scand.a-10772
- Edmond E. Granirer, Exposed points of convex sets and weak sequential convergence, Memoirs of the American Mathematical Society, No. 123, American Mathematical Society, Providence, R.I., 1972. Applications to invariant means, to existence of invariant measures for a semigroup of Markov operators etc. . MR 0365090
- Edmond E. Granirer, The radical of $L^{\infty }(G)^{\ast }$, Proc. Amer. Math. Soc. 41 (1973), 321–324. MR 326302, DOI 10.1090/S0002-9939-1973-0326302-9
- Michael Grosser, Bidualräume und Vervollständigungen von Banachmoduln, Lecture Notes in Mathematics, vol. 717, Springer, Berlin, 1979 (German). MR 542596
- Michael Grosser and Viktor Losert, The norm-strict bidual of a Banach algebra and the dual of $C_{u}(G)$, Manuscripta Math. 45 (1984), no. 2, 127–146. MR 724731, DOI 10.1007/BF01169770
- Niels Groenbaek, A characterization of weakly amenable Banach algebras, Studia Math. 94 (1989), no. 2, 149–162. MR 1025743, DOI 10.4064/sm-94-2-149-162
- Niels Grønbæk, Amenability of weighted discrete convolution algebras on cancellative semigroups, Proc. Roy. Soc. Edinburgh Sect. A 110 (1988), no. 3-4, 351–360. MR 974751, DOI 10.1017/S0308210500022344
- Niels Grønbæk, Amenability of discrete convolution algebras, the commutative case, Pacific J. Math. 143 (1990), no. 2, 243–249. MR 1051075
- A. Grothendieck, Critères de compacité dans les espaces fonctionnels généraux, Amer. J. Math. 74 (1952), 168–186 (French). MR 47313, DOI 10.2307/2372076
- U. Haagerup, All nuclear $C^{\ast }$-algebras are amenable, Invent. Math. 74 (1983), no. 2, 305–319. MR 723220, DOI 10.1007/BF01394319
- S. Hartman and C. Ryll-Nardzewski, Almost periodic extensions of functions. II, Colloq. Math. 15 (1966), 79–86. MR 199651, DOI 10.4064/cm-15-1-79-86
- Edwin Hewitt and Kenneth A. Ross, Abstract harmonic analysis. Vol. I, 2nd ed., Grundlehren der Mathematischen Wissenschaften [Fundamental Principles of Mathematical Sciences], vol. 115, Springer-Verlag, Berlin-New York, 1979. Structure of topological groups, integration theory, group representations. MR 551496
- Edwin Hewitt and Herbert S. Zuckerman, The $l_1$-algebra of a commutative semigroup, Trans. Amer. Math. Soc. 83 (1956), 70–97. MR 81908, DOI 10.1090/S0002-9947-1956-0081908-4
- Neil Hindman, Minimal ideals and cancellation in $\beta \textbf {N}$, Semigroup Forum 25 (1982), no. 3-4, 291–310. MR 679283, DOI 10.1007/BF02573604
- Neil Hindman, The ideal structure of the space of $\kappa$-uniform ultrafilters on a discrete semigroup, Rocky Mountain J. Math. 16 (1986), no. 4, 685–701. MR 871030, DOI 10.1216/RMJ-1986-16-4-685
- Neil Hindman and John Pym, Free groups and semigroups in $\beta \textbf {N}$, Semigroup Forum 30 (1984), no. 2, 177–193. MR 760217, DOI 10.1007/BF02573448
- Neil Hindman and Dona Strauss, Prime properties of the smallest ideal of $\beta \mathbf N$, Semigroup Forum 52 (1996), no. 3, 357–364. MR 1377700, DOI 10.1007/BF02574111
- Neil Hindman and Dona Strauss, Algebra in the Stone-Čech compactification, De Gruyter Expositions in Mathematics, vol. 27, Walter de Gruyter & Co., Berlin, 1998. Theory and applications. MR 1642231, DOI 10.1515/9783110809220
- Neil Hindman and Dona Strauss, Characterization of simplicity and cancellativity in $\beta S$, Semigroup Forum 75 (2007), no. 1, 70–76. MR 2351924, DOI 10.1007/s00233-006-0666-6
- M. Hochster, Subsemigroups of amenable groups, Proc. Amer. Math. Soc. 21 (1969), 363–364. MR 240223, DOI 10.1090/S0002-9939-1969-0240223-0
- John M. Howie, Fundamentals of semigroup theory, London Mathematical Society Monographs. New Series, vol. 12, The Clarendon Press, Oxford University Press, New York, 1995. Oxford Science Publications. MR 1455373
- Nilgün Işık, John Pym, and Ali Ülger, The second dual of the group algebra of a compact group, J. London Math. Soc. (2) 35 (1987), no. 1, 135–148. MR 871771, DOI 10.1112/jlms/s2-35.1.135
- Barry Edward Johnson, Cohomology in Banach algebras, Memoirs of the American Mathematical Society, No. 127, American Mathematical Society, Providence, R.I., 1972. MR 0374934
- B. E. Johnson, Approximate diagonals and cohomology of certain annihilator Banach algebras, Amer. J. Math. 94 (1972), 685–698. MR 317050, DOI 10.2307/2373751
- B. E. Johnson, Weak amenability of group algebras, Bull. London Math. Soc. 23 (1991), no. 3, 281–284. MR 1123339, DOI 10.1112/blms/23.3.281
- B. E. Johnson, Non-amenability of the Fourier algebra of a compact group, J. London Math. Soc. (2) 50 (1994), no. 2, 361–374. MR 1291743, DOI 10.1112/jlms/50.2.361
- Maria Klawe, On the dimension of left invariant means and left thick subsets, Trans. Amer. Math. Soc. 231 (1977), no. 2, 507–518. MR 447970, DOI 10.1090/S0002-9947-1977-0447970-5
- M. Koçak and D. Strauss, Near ultrafilters and compactifications, Semigroup Forum 55 (1997), no. 1, 94–109. MR 1446662, DOI 10.1007/PL00005915
- Anthony To-ming Lau, Topological semigroups with invariant means in the convex hull of multiplicative means, Trans. Amer. Math. Soc. 148 (1970), 69–84. MR 257260, DOI 10.1090/S0002-9947-1970-0257260-5
- Anthony To Ming Lau, Operators which commute with convolutions on subspaces of $L_{\infty }(G)$, Colloq. Math. 39 (1978), no. 2, 351–359. MR 522378, DOI 10.4064/cm-39-2-351-359
- Anthony To Ming Lau, Analysis on a class of Banach algebras with applications to harmonic analysis on locally compact groups and semigroups, Fund. Math. 118 (1983), no. 3, 161–175. MR 736276, DOI 10.4064/fm-118-3-161-175
- Anthony To Ming Lau, Continuity of Arens multiplication on the dual space of bounded uniformly continuous functions on locally compact groups and topological semigroups, Math. Proc. Cambridge Philos. Soc. 99 (1986), no. 2, 273–283. MR 817669, DOI 10.1017/S0305004100064197
- Karl Heinrich Hofmann, Jimmie D. Lawson, and John S. Pym (eds.), The analytical and topological theory of semigroups, De Gruyter Expositions in Mathematics, vol. 1, Walter de Gruyter & Co., Berlin, 1990. Trends and developments. MR 1072781, DOI 10.1515/9783110856040
- A. T. Lau, Fourier and Fourier-Stieltjes algebras of a locally compact group and amenability, Topological vector spaces, algebras and related areas (Hamilton, ON, 1994) Pitman Res. Notes Math. Ser., vol. 316, Longman Sci. Tech., Harlow, 1994, pp. 79–92. MR 1319375
- Anthony To Ming Lau and Viktor Losert, On the second conjugate algebra of $L_1(G)$ of a locally compact group, J. London Math. Soc. (2) 37 (1988), no. 3, 464–470. MR 939122, DOI 10.1112/jlms/s2-37.3.464
- A. T.-M. Lau and R. J. Loy, Weak amenability of Banach algebras on locally compact groups, J. Funct. Anal. 145 (1997), no. 1, 175–204. MR 1442165, DOI 10.1006/jfan.1996.3002
- Anthony To Ming Lau and Alan L. T. Paterson, The exact cardinality of the set of topological left invariant means on an amenable locally compact group, Proc. Amer. Math. Soc. 98 (1986), no. 1, 75–80. MR 848879, DOI 10.1090/S0002-9939-1986-0848879-6
- Anthony To Ming Lau and John Pym, The topological centre of a compactification of a locally compact group, Math. Z. 219 (1995), no. 4, 567–579. MR 1343662, DOI 10.1007/BF02572381
- Anthony To Ming Lau and Ali Ülger, Topological centers of certain dual algebras, Trans. Amer. Math. Soc. 348 (1996), no. 3, 1191–1212. MR 1322952, DOI 10.1090/S0002-9947-96-01499-7
- A. T.-M. Lau, R. J. Loy, and G. A. Willis, Amenability of Banach and $C^*$-algebras on locally compact groups, Studia Math. 119 (1996), no. 2, 161–178. MR 1391474
- A. T. Lau, A. R. Medghalchi, and J. S. Pym, On the spectrum of $L^\infty (G)$, J. London Math. Soc. (2) 48 (1993), no. 1, 152–166. MR 1223900, DOI 10.1112/jlms/s2-48.1.152
- E. S. Ljapin, Semigroups, 3rd ed., Translations of Mathematical Monographs, Vol. 3, American Mathematical Society, Providence, R.I., 1974. Translated from the 1960 Russian original by A. A. Brown, J. M. Danskin, D. Foley, S. H. Gould, E. Hewitt, S. A. Walker and J. A. Zilber. MR 0352302
- V. Losert, Weakly compact multipliers on group algebras, J. Funct. Anal. 213 (2004), no. 2, 466–472. MR 2078634, DOI 10.1016/j.jfa.2003.10.012
- Nicholas Macri, The continuity of Arens’ product on the Stone-Čech compactification of semigroups, Trans. Amer. Math. Soc. 191 (1974), 185–193. MR 382541, DOI 10.1090/S0002-9947-1974-0382541-8
- Paul Milnes, Uniformity and uniformly continuous functions for locally compact groups, Proc. Amer. Math. Soc. 109 (1990), no. 2, 567–570. MR 1023345, DOI 10.1090/S0002-9939-1990-1023345-7
- Theodore Mitchell, Fixed points and multiplicative left invariant means, Trans. Amer. Math. Soc. 122 (1966), 195–202. MR 190249, DOI 10.1090/S0002-9947-1966-0190249-2
- Theodore Mitchell, Topological semigroups and fixed points, Illinois J. Math. 14 (1970), 630–641. MR 270356
- W. D. Munn, On semigroup algebras, Proc. Cambridge Philos. Soc. 51 (1955), 1–15. MR 66355, DOI 10.1017/s0305004100029868
- I. Namioka, On certain actions of semi-groups on $L$-spaces, Studia Math. 29 (1967), 63–77. MR 223863, DOI 10.4064/sm-29-1-63-77
- Matthias Neufang, A unified approach to the topological centre problem for certain Banach algebras arising in abstract harmonic analysis, Arch. Math. (Basel) 82 (2004), no. 2, 164–171. MR 2047670, DOI 10.1007/s00013-003-0516-7
- Matthias Neufang, On a conjecture by Ghahramani-Lau and related problems concerning topological centres, J. Funct. Anal. 224 (2005), no. 1, 217–229. MR 2139110, DOI 10.1016/j.jfa.2004.11.007
- Matthias Neufang, On the topological centre problem for weighted convolution algebras and semigroup compactifications, Proc. Amer. Math. Soc. 136 (2008), no. 5, 1831–1839. MR 2373615, DOI 10.1090/S0002-9939-08-08908-9
- Theodore W. Palmer, Banach algebras and the general theory of $^*$-algebras. Vol. I, Encyclopedia of Mathematics and its Applications, vol. 49, Cambridge University Press, Cambridge, 1994. Algebras and Banach algebras. MR 1270014, DOI 10.1017/CBO9781107325777
- Theodore W. Palmer, Banach algebras and the general theory of $*$-algebras. Vol. 2, Encyclopedia of Mathematics and its Applications, vol. 79, Cambridge University Press, Cambridge, 2001. $*$-algebras. MR 1819503, DOI 10.1017/CBO9780511574757.003
- D. J. Parsons, The centre of the second dual of a commutative semigroup algebra, Math. Proc. Cambridge Philos. Soc. 95 (1984), no. 1, 71–92. MR 727082, DOI 10.1017/S0305004100061326
- Alan L. T. Paterson, Amenability, Mathematical Surveys and Monographs, vol. 29, American Mathematical Society, Providence, RI, 1988. MR 961261, DOI 10.1090/surv/029
- I. V. Protasov, Topological center of a semigroup of free ultrafilters, Mat. Zametki 63 (1998), no. 3, 437–441 (Russian, with Russian summary); English transl., Math. Notes 63 (1998), no. 3-4, 384–387. MR 1631893, DOI 10.1007/BF02317786
- I. V. Protasov and J. S. Pym, Continuity of multiplication in the largest compactification of a locally compact group, Bull. London Math. Soc. 33 (2001), no. 3, 279–282. MR 1817766, DOI 10.1017/S0024609301007925
- John S. Pym, The convolution of functionals on spaces of bounded functions, Proc. London Math. Soc. (3) 15 (1965), 84–104. MR 173152, DOI 10.1112/plms/s3-15.1.84
- John Pym, Semigroup structure in Stone-Čech compactifications, J. London Math. Soc. (2) 36 (1987), no. 3, 421–428. MR 918634, DOI 10.1112/jlms/s2-36.3.421
- D. Rees, On semi-groups, Proc. Cambridge Philos. Soc. 36 (1940), 387–400. MR 2893
- D. Rees, Note on semi-groups, Proc. Cambridge Philos. Soc. 37 (1941), 434–435. MR 5743
- Walter Rudin, Real and complex analysis, McGraw-Hill Book Co., New York-Toronto-London, 1966. MR 0210528
- Volker Runde, Amenability for dual Banach algebras, Studia Math. 148 (2001), no. 1, 47–66. MR 1881439, DOI 10.4064/sm148-1-5
- Volker Runde, Banach space properties forcing a reflexive, amenable Banach algebra to be trivial, Arch. Math. (Basel) 77 (2001), no. 3, 265–272. MR 1865868, DOI 10.1007/PL00000490
- Volker Runde, Lectures on amenability, Lecture Notes in Mathematics, vol. 1774, Springer-Verlag, Berlin, 2002. MR 1874893, DOI 10.1007/b82937
- Volker Runde, The amenability constant of the Fourier algebra, Proc. Amer. Math. Soc. 134 (2006), no. 5, 1473–1481. MR 2199195, DOI 10.1090/S0002-9939-05-08164-5
- Volker Runde, Cohen-Host type idempotent theorems for representations on Banach spaces and applications to Figà-Talamanca-Herz algebras, J. Math. Anal. Appl. 329 (2007), no. 1, 736–751. MR 2306837, DOI 10.1016/j.jmaa.2006.07.007
- Volker Runde and Nico Spronk, Operator amenability of Fourier-Stieltjes algebras, Math. Proc. Cambridge Philos. Soc. 136 (2004), no. 3, 675–686. MR 2055055, DOI 10.1017/S030500410300745X
- Volker Runde and Nico Spronk, Operator amenability of Fourier-Stieltjes algebras. II, Bull. Lond. Math. Soc. 39 (2007), no. 2, 194–202. MR 2323448, DOI 10.1112/blms/bdl026
- Saharon Shelah, Proper forcing, Lecture Notes in Mathematics, vol. 940, Springer-Verlag, Berlin-New York, 1982. MR 675955
- Ross Stokke, Approximate diagonals and Følner conditions for amenable group and semigroup algebras, Studia Math. 164 (2004), no. 2, 139–159. MR 2079635, DOI 10.4064/sm164-2-3
- Eric K. van Douwen, The maximal totally bounded group topology on $G$ and the biggest minimal $G$-space, for abelian groups $G$, Topology Appl. 34 (1990), no. 1, 69–91. MR 1035461, DOI 10.1016/0166-8641(90)90090-O
- Carroll Wilde and Klaus Witz, Invariant means and the Stone-Čech compactification, Pacific J. Math. 21 (1967), 577–586. MR 212552
- Edward L. Wimmers, The Shelah $P$-point independence theorem, Israel J. Math. 43 (1982), no. 1, 28–48. MR 728877, DOI 10.1007/BF02761683
- Klaus G. Witz, Applications of a compactification for bounded operator semigroups, Illinois J. Math. 8 (1964), 685–696. MR 178368
- Zhuocheng Yang, On the set of invariant means, J. London Math. Soc. (2) 37 (1988), no. 2, 317–330. MR 928526, DOI 10.1112/jlms/s2-37.2.317
- N. J. Young, Separate continuity and multilinear operations, Proc. London Math. Soc. (3) 26 (1973), 289–319. MR 324376, DOI 10.1112/plms/s3-26.2.289
- N. J. Young, Semigroup algebras having regular multiplication, Studia Math. 47 (1973), 191–196. MR 330923, DOI 10.4064/sm-47-2-191-196
- N. J. Young, The irregularity of multiplication in group algebras, Quart. J. Math. Oxford Ser. (2) 24 (1973), 59–62. MR 320756, DOI 10.1093/qmath/24.1.59
- Yong Zhang, Weak amenability of a class of Banach algebras, Canad. Math. Bull. 44 (2001), no. 4, 504–508. MR 1863642, DOI 10.4153/CMB-2001-050-7