Alcides Buss

Seminário de C*-Álgebras

Research area: Operator Algebras

Research interests: several aspects of noncommutative dynamical systems, actions of group(oid)s on C*-algebras, Fell bundles, quantum groups, groupoids and (inverse) semigroups, p-adic operator algebras.

Papers (in inverse chronological order):

1. Bruno de Mendonça Braga, Alcides Buss, Ruy Exel, Flows on uniform Roe algebras, preprint
2. Alcides Buss, Bartosz Kwaśniewski, Andrew McKee, Adam Skalski, Fourier-Stieltjes category for twisted groupoid actions, preprint
3. Pere Ara, Alcides Buss and Ado Dalla Costa, Inverse semigroups of separated graphs and associated algebras, preprint
4. Alcides Buss, Luiz Felipe Garcia and Devarshi Mukherjee, Operator algebras over the p-adic integers, preprint
5. Alcides Buss and Siegfried Echterhoff, Deformation of Fell bundles, preprint, submitted for publication
6. Alcides Buss and Siegfried Echterhoff, A new approach to deformation of C*-algebras via coactions, preprint, submitted for publication
7. Nathan Brownlowe, Alcides Buss, Daniel Gonçalves, Jeremy B. Hume, Aidan Sims, Michael F. Whittaker, KK-duality for self-similar groupoid actions on graphs, Trans. Amer. Math. Soc. 377(2024), no.8, 5513-5560. ,
8. Alcides Buss and Diego Martínez, Approximation properties of Fell bundles over inverse semigroups and non-Hausdorff groupoids, Advances in Mathematics, Vol. 431, 376 (2023),
9. Pere Ara, Alcides Buss and Ado Dalla Costa, Free actions of groups on separated graph C*-algebras , Trans. Amer. Math. Soc. 376 (2023), no. 4, 2875-2919,
10. Alcides Buss, Damian Ferraro and Camila Sehnem, Nuclearity for partial crossed products by exact discrete groups , Journal of Operator Theory, 88:1(2022), 83-115
11. Alcides Buss, Siegfried Echterhoff and Rufus Willett, Amenability and weak containment for actions of locally compact groups on C*-algebras, Memoirs of the American Mathematical Society In press: Volume 301, Number 1513.
12. Alcides Buss, Siegfried Echterhoff and Rufus Willett, Erratum for ''The minimal exact crossed product'' Doc. Math. 26 (2021), 1629-1632, 53 (2022), no. 1, 173--227
13. Fernando Abadie, Alcides Buss and Damian Ferraro, Amenability and approximation properties for partial actions and Fell bundles. Bull Braz Math Soc, New Series 53 (2022), no. 1, 173--227
14. Paolo Antonini, Alcides Buss, Alexander Engel, Timo Siebenand, Strong Novikov conjecture for low degree cohomology and exotic group C*-algebras. Trans. Amer. Math. Soc. 374 (2021), no. 7, 5071--5093
15. Alcides Buss and Ralf Meyer, Iterated crossed products for groupoid fibrations, preprint.
16. Alcides Buss, Siegfried Echterhoff and Rufus Willett, Injectivity, crossed products, and amenable group actions, (chapter in K-theory in algebra, analysis and topology), Contemp. Math., 749, 105--137, Amer. Math. Soc., [Providence], RI, [2020].
17. Alcides Buss and Aidan Sims, Opposite algebras of groupoid C*-algebras, Israel Journal of Mathematics. 244, pages 759-774 (2021)
18. Alcides Buss, Siegfried Echterhoff and Rufus Willett, The maximal injective crossed product, Ergodic Theory and Dynamical Systems 40 (2020), no. 11, 2995--3014.
19. Alcides Buss, Siegfried Echterhoff and Rufus Willett, The minimal exact crossed product, Documenta Math. 23 (2018) 2043-2077
20. Fernando Abadie, Alcides Buss and Damian Ferraro, Morita enveloping Fell bundles, Bull Braz Math Soc, New Series Online version (2018)
21. Alcides Buss, Rohit Holkar and Ralf Meyer, A universal property for groupoid C*-algebras. I, Proc. London Math. Society. 117 (2018), no. 2, 345-375
22. Alcides Buss and Ralf Meyer, Crossed products for actions of crossed modules on C*-algebras, Journal of Noncommutative Geometry. 11 (2017), no. 3, 1195-1235
23. Alcides Buss, Ruy Exel and Ralf Meyer, Reduced C*-algebras of Fell bundles over inverse semigroups, Israel Journal of Mathematics. 220 (2017), no. 1, 225-274.
24. Alcides Buss and Ralf Meyer, Inverse semigroup actions on groupoids, vol. 47, no. 1 (2017), 53-159, Rocky Mountain Journal of Mathematics.
25. Alcides Buss and Siegfried Echterhoff, Rieffel proper actions, Journal of Operator Theory vol. 75, Issue 1 (2016), 49-73,
26. Alcides Buss and Siegfried Echterhoff, Weakly proper group actions, Mansfield's imprimitivity and twisted Landstad duality, Trans. Amer. Math. Soc., vol. 368 (2016), 249-280 ,
27. Alcides Buss, Siegfried Echterhoff and Rufus Willett, Exotic Crossed Products, survey paper published as a chapter in Proceedings of The Abel Symposium 2015 - Operator Algebras and Applications.
28. Alcides Buss, Siegfried Echterhoff and Rufus Willett, Exotic crossed products and the Baum-Connes conjecture, Crelles Journal, online version (2015),
29. Alcides Buss and Siegfried Echterhoff, Maximality of dual coactions on sectional C*-algebras of Fell bundles and applications, Studia Mathematica, 229(2015), 233-262 ,
30. Alcides Buss and Siegfried Echterhoff, Imprimitivity theorems for weakly proper actions of locally compact groups, Erg. Theory Dyn. Systems., vol. 35, nr. 08 (2015), 2412-2457
31. Alcides Buss and Siegfried Echterhoff, Universal and exotic generalized fixed-point algebras for weakly proper actions and duality, Indiana Univ. Math. Journal, vol. 63, nr. 6 (2014), 1659-1701 ,
32. Alcides Buss, Generalized fixed point algebras for coactions of locally compact quantum groups, Münster Journal of Mathematics 6 (2013), 295-341
33. Alcides Buss, Ralf Meyer and Chenchang Zhu, A higher category approach to twisted actions on C*-algebras, Proc. Edinb. Math. Soc., vol. 56, 2013, 387-426.
34. Alcides Buss and Ruy Exel, Inverse semigroup expansions and their actions on C*-Algebras, Illinois J. Math. 56, Nr 4 (2012), 1001-1343
35. Alcides Buss, Ruy Exel and Ralf Meyer, Inverse semigroup actions as groupoid actions, Semigroup Forum, vol. 85, 2012, 227-243.
36. Alcides Buss, Ralf Meyer and Chenchang Zhu, Non-Hausdorff symmetries of C*-algebras, Math. Ann., vol. 352, 2012, nr. 1, 73-97.
37. Alcides Buss and Ruy Exel, Fell bundles over inverse semigroups and twisted étale groupoids, J. Operator Theory, vol. 67, 2012, 153-205.
38. Alcides Buss and Ruy Exel, Twisted actions and regular Fell bundles over inverse semigroups, Proc. London Math. Soc., vol. 103, 2011, 235-270.
39. Alcides Buss, Integrability of dual coactions on Fell bundle C*-algebras, Bull. Braz. Math. Soc. (N.S.), vol. 41, 2010, nr. 4, 607-641.
40. Alcides Buss and Ralf Meyer, Square-integrable coactions of locally compact quantum groups, Reports on Mathematical Physics, vol. 63, 2009, nr. 1, 191-224.
41. Alcides Buss, A generalized Fourier inversion Theorem, Bull. Braz. Math. Soc. (N.S.), vol. 39, 2008, nr. 4, 555-571.
42. Alcides Buss and Ralf Meyer, Continuous spectral decompositions of abelian group actions on C*-algebras, J. Funct. Anal., vol. 253, 2007, nr. 2, 482-514.

Dissertations:

• My master dissertation "A C*-algebra de um grupo" (in portuguese) is available here.


• My doctoral dissertation "Generalized fixed point algebras for coactions of locally compact quantum groups" is available here.

Short Curriculum Vitae

1979 born in Palhoça (Brazil)

1997-2000 mathematics studies at UFSC (Universidade Federal de Santa Catarina), Florianópolis

2000 Bachelor's degree in mathematics at UFSC, Florianópolis

2001-2002 master studies at UFSC, Florianópolis

2002 master's degree in mathematics at UFSC, Florianópolis (supervisor Ruy Exel)

2003 assistant professor at UFSC, Florianópolis

2004-2007 doctoral studies at WWU (Westfälische Williams Universität), Münster (Germany)

2007 doctoral degree in mathematics at WWU (supervisors Ralf Meyer and Siegfried Echterhoff), Münster

2008 postdoctoral studies at UFSC (with Ruy Exel)

since 2009 associate professor at UFSC

2013 postdoctoral sabbatical year at the Work group of Functional Analysis, Operator Algebras and Noncommutative Geometry, Münster

2018 postdoctoral sabbatical year at the Work group of Functional Analysis, Operator Algebras and Noncommutative Geometry, Münster

2023 postdoctoral sabbatical year at the Work group of Functional Analysis, Operator Algebras and Noncommutative Geometry, Münster

Awards and Honours

1997-2000 Member of PET (Special Programm of Mathematics) at UFSC

2000 Best Student at Federal University of Santa Catarina (UFSC) 1997-2000 having obtained the best grade among all students of mathematics.

2001-2008 Fellowships from several organizations, including CNPQ, CAPES, DAAD and Humboldt.

2010 Invited Speaker to participate in the "7th Regional Conference of Young Scientists of TWAS-ROLAC" at the Brazilian Academy of Sciences

since 2012 CNPq research productivity scholarship (Bolsista de Produtividade em Pesquisa CNPq - Nível 1)

Foreign Languages (native Brazilian Portuguese): English and German

Teaching Experience

• Calculus
• Linear Algebra
• Complex Analysis
• Algebra
• Analysis
• Operator Algebras
• C*-algebras
• K-theory for C*-algebras
• Fell bundles and Hilbert Modules
• C*-dynamical Systems, Crossed Products
• Inverse semigroups and groupoid C*-algebras

Dissertations:

• My master dissertation "A C*-algebra de um grupo" (in portuguese) is available here.


• My doctoral dissertation "Generalized fixed point algebras for coactions of locally compact quantum groups" is available here.

Participation in Events

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• K-theory and Operator Algebras - 2025 CIMPA School - August 04-08, 2025, Buenos Aires, Argentina. Mini-Course: C*-algebras of twisted étale groupoids and Cartan pairs

• Mathematical Analysis, Geometry and Dynamical Systems Seminar - IST - Dezember 17, 2024, Lisbon, Portugal. Talk: Amenability and nuclearity of essential groupoid C*-algebras

• XXVII Escola de Álgebra - Special Session at Algebraic Methods in Various Areas - July 15-19, 2024, São Paulo, Brazil. Talk: Operator algebras over the p-adic integers

• Great Plains Operator Theory Symposium (GPOTS) - June 03-07, 2024, Lincoln-Nebraska, USA. Talk: Amenability and approximation properties for C*-algebraic dynamical systems

• Summer Programm - Programa de Verão - IMPA - January 14-28, 2024, Rio de Janeiro, Brazil. Mini-course: Uma introdução as Álgebras de Operadores através de Grupoides

• NCG&T Prague - November 14, 2023, Prague, Czech Republic.. Invited talk: Nuclearity for C*-algebras of Fell bundles

• Seminar Algebra-Geometrie-Kombinatorik - November 09, 2023, Dresden, Germany.. Invited talk: Deformation Quantization of Operator Algebras

• Oberseminar C*-Algebren - October 17, 2023, Münster, Germany. Invited talk: Deformation of C*-algebras

• Topics in K-theory and NCG - Conference to honor the contributions of Guillermo Cortiñas on his 60th birthday - July 24-28, 2023, Buenos Aires, Argentina. Invited talk: Deformation of C*-algebras via coactions

• Seminar on Deformation Quantization - July 14, 2023, Würzburg, Germany. Invited talk: A new approach to Rieffel Deformation of C*-algebras via coactions of groups

• Seminar on Deformation Quantization - June 02, 2023, Würzburg, Germany. Invited talk: Landstad duality and Rieffel deformation

• I Encontro de Pós-Graduandos em Matemática na UFSC - Dec 02, 2022, Florianópolis. Apresentação de área: Álgebras de Operadores

• NCG&T Seminar - May 24, 2022, Prague, Czech Republic. Invited talk: Free actions of groups on separated graphs and their C*-algebras

• Glasgow Analysis Seminar - March 24, 2022, Glasgow, Scotland. Invited talk: Free actions of groups on separated graphs and their C*-algebras

• Together with Damián Ferraro and Fernando Abadie, I organized the Operator Algebras special session at the CLAM 2021 - Universidad de la Republica - Montevideo, 13-17 September, 2021.

• Groups meet C*-algebras - 28 June - 9 July 2021, Münster, Germany. Invited talk: On my collaboration with Siegfried Echterhoff

• Oberseminar C*-Algebren - April 20, 2021, Münster, Germany. Invited talk: Free actions of groups on separated graphs and their C*-algebras

• The First WSU-IPM Joint Workshop on Operator Algebras - September 30-October 2, 2020, Online Workshop. Invited Speaker: Amenability for Actions of Groups on C*-algebras

• Colóquio do Departamento de Matemática - 09/out/2020, Online, Florianópolis - UFSC. Palestrante convidado: Amenabilidade de grupos e suas ações sobre C*-álgebras

• Glasgow Analysis Seminar - December 12, 2019, Glasgow, Scotland. Invited talk: Amenability and approximation properties of C*-dynamical systems

• XXX International Workshop on Operator Theory and Applications -IWOTA - July 22-26, 2019, Lisbon, Portugal. Invited Speaker: Amenability of (partial) actions and Fell bundles

• IV Workshop on Dynamics, Numeration and Tilings (IV FloripaDynSys) - 29 Apr-3 May 2019, Florianópolis, Brazil. Invited Speaker: Amenable actions and crossed products

• Together with Pere Ara, Ruy Exel and Francesc Perera, I organized the Operator Algebras special session at the II Encuentro Conjunto RSME-SEMA-SBM-SBMAC - Universidad de Cádiz - Espanha, 11 a 14 de dezembro, 2018.

• Together with Daniel Gonçalves, Gilles Castro, Giuliano Boava e Viviane Beuter, I organized the ICM Operator Algebras Satellite Conference - ICMOA - July 26-30, 2018 in Florianópolis, Brazil.

• NCGOA 2018: C*-algebras and Dynamics - May 14-19, 2018, Münster, Germany.

• Together with Paul Bressler, I organized the Operator Algebra special session at the XXII Coloquio Latino Americano de Algebra (XXII CLA) - 07-11 August 2017, Quito, Equador.

• Satellite Conference on Operator Algebras (MCA2017) - 31 July -04 August 2017, Toronto, Canada. Invited Speaker: Proper actions of groups on C*-algebras and applications

• Mathematical Congress of the Americas - 24-28 July 2017, Montreal, Canada. Invited Speaker: Groupoid actions - The symmetries of noncommutative spaces

• IX Jornada de Álgebra - 04-06 Maio 2017, UEM, Maringá, Brasil. Invited Speaker, Plenary talk: Grupóides e suas ações sobre C*-álgebras

• I Encontro Em Categorias Tensoriais E Suas Representações, 02-03 Março 2017, UFSC, Florianópolis, Brasil. Invited Speaker. Title of the talk: Simetrias não-comutativas: Um tratamento bicategórico

• XXI Coloquio Latinoamericano de Álgebra - Buenos Aires - Argentina, 25-29 July 2016. Invited Speaker. Title of the talk: Groupoid fibrations and their C*-algebras

• Workshop on New Directions in Inverse Semigroups - Ottawa - Canada, 01-04 June 2016.

• Workshop on Dynamical Systems and Operator Algebras - Ottawa - Canada, 29 May - 01 June 2016. Invited Speaker. Title of the talk: Inverse semigroups, groupoids and their actions on C*-algebras

• I organized, together with Pere Ara, Ruy Exel, and Enrique Pardo, the special session on Operator Algebras at the First Joint Meeting Brazil-Spain in Mathematics - Fortaleza - Brazil, 07-10 Dez 2015.

• Workshop on C*-algebras: Geometry and Actions - Münster - Germany, 13-17 July 2015. Speaker. Title of the talk: Symmetries of Noncommutative Spaces

• I organized, together with Daniel Gonçalves, Vladimir Pestov, and Marcelo Sobottka, the Workshop on Functional Analysis and Dynamical Systems - Florianópolis - Brazil, 23-27 Fev 2015.

• I organized, together with Roman Sasyk, the Special Session on Operator Algebras at the XX Coloquio Latinoamericano de Algebra - Lima - Peru, 08-12 Dez 2014.

• Partial Actions and Representations Symposium (PARS) - Gramado - Brazil, 11-15 May 2014. Speaker. Title of the talk: Actions of inverse semigroups on groupoids by partial equivalences

• Análise funcional geométrica e ações de grupos (Geometric functional analysis and group actions) - Florianópolis - Brazil, 19-21 Feb 2014. Invited Speaker. Title of the talk: Weakly proper actions, imprimitivity theorems and duality

• SFB Miniworkshop on C*-Algebras, C*-Bundles, and Group Actions - Münster - Germany, 25-29 November 2013.

• Noncommutative Geometry - Oberwolfach - Germany, 8 Sep - 14 Sep 2013.

• From August 20 to August 24, 2013, I organized, together with Siegfried Echterhoff, in Münster, Germany, the conference: Groups, Dynamical Systems and C*-Algebras

  Quantum Groups and 3-Manifold Invariants , IMPA, Rio de Janeiro, September 5-7, 2012.
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  IV Congreso Latinoamericano de Matemáticos (IV CLAM) , Universidad Nacional de Córdoba, Córdoba, August 6-10, 2012.
  Invited Speaker. Title of the talk: C*-Dynamical Systems and their Crossed Products.
  XV Latinamerican School of Mathematics (XV ELAM) - CIMPA research school - Cordoba, Argentina, May 16-27, 2011.
  Invited Speaker. Title of the talk: Decompositions of C*-algebras by Fell Bundles.
  Participation in the summer programme at IMPA (Instituto de Matemática Pura e Aplicada), 2011. Invited (by Henrique Bursztyn) to give a mini-course: Introdução às C*-álgebras.
  Organizer and Main Speaker of the Brazilian Operator Algebra Symposium, Florianópolis, Brazil, 2011. Title of the mini-course: Proper actions of groups on C*-algebras.
  Topics in Noncommutative Geometry: 3era Escuela de Invierno Luis Santaló -CIMPA Research School, Buenos Aires, Argentina, 2010. (Supported by CIMPA.)
  Extended Workshop on Groups and Group Actions in Operator Algebra Theory , Ottawa, Canada, 2010. Invited Speaker, Title of the talk: Fell bundle structures for C*-algebras.
  69th Seminário Brasileiro de Análise, Florianópolis, São Paulo, Brazil, 2009.
  27th Colóquio Brasileiro de Matemática, IMPA, Rio de Janeiro, Brazil, 2009.
  Workshop on Operator algebraic aspects of quantum groups, Leuven, Belgium, 2008.
  67th Seminário Brasileiro de Análise, São Paulo, Brazil, 2008.
  66th Seminário Brasileiro de Análise, São Paulo, Brazil, 2007.
  Meeting on the structure of C*-algebras (in honor of Eberhard Kirchberg on the occasion of his 60th birthday), Münster, Germany, 2007.
  Workshop "Noncommutative Algebras";, Münster, Germany, 2006.
  Workshop C*-Algebren , Oberwolfach, Germany, 2005.
  Workshop on index theory, Münster, Germany, 2005.
  23th Colóquio Brasileiro de Matemática, IMPA, Rio de Janeiro, Brazil, 2001.
  Participation at Summer Programm at IMPA, Rio de Janeiro, Brazil, 2000.
  9th Seminário de Iniciação Científica, Florianópolis, Brazil, 1999.
  22th Colóquio Brasileiro de Matemática, IMPA, Rio de Janeiro, Brazil, 1999.
  21st Congresso Nacional de Matemática Aplicada e Computacional, Minas Gerais, Brazil, 1998.

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  My Curriculum Vitae Lattes: in Portuguese, in English
  Also available: CV in pdf form (last updated in March 2022)

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  My ArXiv Preprints

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  My Papers and Citations at Google Scholar

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  My Profile at MathSciNet

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  Articles I've reviewed at Zentralblatt

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  My Profile at Zentralblatt

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  Homepages of my co-authors: Siegfried Echterhoff, Ruy Exel, Ralf Meyer, Aidan Sims, Rufus Willett, Chenchang Zhu

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  Some interesting links:

  Schedule for some Operator Algebras Conferences

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  Network on Operator Algebras and Noncommutative Geometry in South America and France

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  Search in the local library (BU - UFSC)

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  Clustrmaps since May 31, 2014: