Jorge Almeida's home page

Contacts

• Normally based at:
• Address:

        Centro de Matemática
        Departamento de Matemática
        Faculdade de Ciências
        Universidade do Porto
        Rua do Campo Alegre, 687
        4169-007 Porto, Portugal

• Phone:

     +351 220402132 (my office)
     +351 220402103 (department)

• Fax:

     +351 220402108 (department);
     this is a shared fax, so be sure to include my name;

• E-mail: jalmeida AT fc DOT up DOT pt

Editorial boards

• Boletim da Sociedade Portuguesa de Matemática (member of editorial council and book review editor)
• Discussiones Mathematicae - General Algebra and Applications
• International Journal of Algebra and Computation
• Portugaliae Mathematica (associate editor)
• Semigroup Forum (also book review editor)

Software tools

Publications

Some day, if I ever find the time and it still makes sense to do it, a more
comprehensive list of my most relevant publications may be made available here...
 
	  

• Books:
• J. Almeida, G. Bordalo, and P. Dwinger (Eds.), Lattices, Semigroups and Universal Algebra, Plenum, New York, 1990. ISBN: 0-306-43412-1.
• J. Almeida, G. M. S. Gomes, and P. V. Silva (Eds.), Semigroups, Automata and Languages, World Scientific, Singapore, 1996, ISBN: 981-02-2515-6.
• J. Almeida, Finite Semigroups and Universal Algebra, World Scientific, Singapore, 1995, ISBN: 981-02-1895-8
• J. Almeida, A. Costa, R. Kyriakoglou, D. Perrin, Profinite Semigroups and Symbolic Dynamics, Lecture Notes in Mathematics 2274, Springer, Cham, 2020, ISBN: 978-3-030-55215-2 (ebook) 978-3-030-55214-5 (softcover)
• Papers since 1996:
1. (CMUP 96-1).
   J. Almeida, Syntactic methods in finite semigroup theory.
   Proc. Int. Conf. ``Semigroups and their applications, including semigroup rings'' (St.-Petersburg, Russia, 19-30 June, 1995), S. Kublanovsky, A. Mikhalev, P. Higgins, and J. Ponizovskii (eds.), TPO ``Sverny Ochag'', St Petersburg, 1999, 1-21.
   (PostScript file of preprint available).
2. (CMUP 96-2).
   J. Almeida and P. M. Higgins, Monoids respecting n-chains of intervals.
   J. Algebra 187 (1997) 183-202.
3. (CMUP 96-6).
   J. Almeida and M. V. Volkov, The gap between partial and full.
   Int. J. Algebra and Computation 8 (1998) 399-430.
   (PostScript file of preprint available).
4. (CMUP 96-9).
   Jorge Almeida, Some algorithmic problems for pseudovarieties.
   Publ Math. Debrecen 54 Suppl. (1999) 531-552.
   (PostScript file of preprint available).
5. (CMUP 96-10).
   Jorge Almeida, Power exponents of aperiodic pseudovarieties.
   Semigroup Forum 59 (1999) 18-32.
   (PostScript file of preprint available).
6. (CMUP 96-11).
   Jorge Almeida, Hyperdecidable pseudovarieties and the calculation of semidirect products.
   Int. J. Algebra and Computation 9 (1999) 241-261.
   (PostScript file of preprint available).
7. (CMUP 97-1).
   J. Almeida and M. Zeitoun, The pseudovariety J is hyperdecidable.
   Theor. Inf. and Appl. 31 (1997) 457-482.
   (PostScript file of preprint available).
8. (CMUP 97-2).
   J. Almeida, A. Azevedo and L. Teixeira, On finitely based pseudovarieties of the forms V*D and V*D_n.
   J. Pure and Applied Algebra 146 (2000) 1-15.
   (PostScript file of preprint available).
9. (CMUP 97-10).
   J. Almeida, A. Azevedo and M. Zeitoun, Pseudovariety joins involving J-trivial semigroups and completely regular semigroups.
   Int. J. Algebra and Computation 9 99-112.
   (PostScript file of preprint available).
10. (CMUP 97-11).
    Jorge Almeida and Pedro V. Silva, SC-Hyperdecidability of R.
    Theor. Comp. Sci. 255 (2001) 569-591.
    (PostScript file of preprint available).
11. (CMUP 97-20).
    Jorge Almeida and Pedro V. Silva, On the hyperdecidability of semidirect products of pseudovarieties.
    Comm. in Algebra 26 (1998) 4065-4077.
    (PostScript file of preprint available).
12. (CMUP 97-21).
    Jorge Almeida, On hyperdecidable pseudovarieties of simple semigroups.
    Int. J. Algebra and Computation 10 (2000) 261-284.
    (PostScript file of preprint available).
13. (CMUP 97-25).
    Jorge Almeida, Power semigroups: results and problems.
    Algebraic Engineering, M. Ito and C. Nehaniv (eds.), World Scientific, Singapore, 1999, 399-415.
    (PostScript file of preprint available).
14. (CMUP 97-27).
    Jorge Almeida and Benjamin Steinberg, On the decidability of iterated semidirect products with applications to complexity.
    Proc. London Math. Soc. 80 (2000) 50-74.
    (PostScript file of preprint available).
15. (CMUP 97-30).
    Jorge Almeida and Manuel Delgado, Sur certains systèmes d'équations avec contraintes dans un groupe libre.
    Port. Math. 56 (1999) 409-417.
    (PostScript file of preprint available).
16. (CMUP 97-32).
    Jorge Almeida, On a problem of Brzozowski and Fich.
    Semigroups and Applications, J. M. Howie and N. Ruskuc (eds.), World Scientific, Singapore, 1999, 1-17.
    (PostScript file of preprint available).
17. (CMUP 98-6).
    Jorge Almeida and Ana Escada, On the equation V * G = EV.
    J. Pure Appl. Algebra 166 (2002) 1-28.
    (PostScript file of preprint available).
18. (CMUP 98-11).
    Jorge Almeida and Benjamin Steinberg, Syntactic and global semigroup theory, a synthesis approach.
    Algorithmic Problems in Groups and Semigroups, J. C. Birget, S. W. Margolis, J. Meakin, and M. V. Sapir (eds.), Birkhäuser, 2000, 1-23.
    (PostScript file of preprint available).
19. (CMUP 99-8).
    Jorge Almeida and Peter G. Trotter, Hyperdecidability of pseudovarieties of orthogroups.
    Glasgow Math. J. 43 (2001) 67-83.
    (PostScript file of preprint available).
20. (CMUP 99-10).
    Jorge Almeida and Assis Azevedo, Globals of pseudovarieties of commutative semigroups: the finite basis problem, decidability, and gaps.
    Proc. Edinburgh Math. Soc. 44 (2001) 27-47.
    (PostScript file of preprint available).
21. (CMUP 99-11).
    Jorge Almeida, P. M. Higgins and M. V. Volkov, The gap between partial and full: an addendum.
    Int. J. Algebra and Computation 11 (2001) 131-135.
    (PostScript file of preprint available).
22. (CMUP 99-22).
    Jorge Almeida and Manuel Delgado, Sur certains systèmes d'équations avec contraintes dans un groupe libre--addenda.
    Portugal. Math. 58 (2001) 379-387.
    (PostScript file of preprint available).
23. (CMUP 99-24).
    Jorge Almeida and Marc Zeitoun, Tameness of some locally trivial pseudovarieties.
    Comm. Algebra 31 (2003) 61-77.
    (PostScript file of preprint available).
24. (CMUP 2000-01).
    Jorge Almeida, Dynamics of implicit operations and tameness of pseudovarieties of groups.
    Trans. Amer. Math. Soc. 354 (2001) 387-411.
    (Revised PostScript file of preprint available).
25. (CMUP 2000-02).
    Jorge Almeida, Finite semigroups: jewels and problems.
    (PostScript file available).
26. (CMUP 2000-11).
    Jorge Almeida, Tameness of pseudovarieties of semigroups.
    (PostScript file available).
27. (CMUP 2000-23).
    Jorge Almeida and Ana Escada, Semidirect products with the pseudovariety of all finite groups.
    (PostScript file available).
28. (CMUP 2000-24).
    Jorge Almeida and Peter G. Trotter, The word problem for free profinite semigroups over the pseudovariety CR and k-reducibility.
    (published under the title The pseudoidentity problem and reducibility for completely regular semigroups)
    Bull. Austral. Math. Soc. 63 (2001) 407-433.
    (PostScript file of preprint available).
29. (CMUP 2001-02).
    Jorge Almeida and Mikhail V. Volkov, Profinite methods in finite semigroup theory.
    (PostScript file available).
30. (CMUP 2001-10).
    Jorge Almeida, Some key problems on finite semigroups.
    Semigroup Forum 64 (2002) 159-179.
    (PostScript file of preprint available).
31. (CMUP 2001-16).
    Jorge Almeida, Dynamics of finite semigroups.
    In G. M. S. Gomes, J.-E. Pin and P. V. Silva (eds.), Semigroups, Algorithms, Automata and Languages, World Scientific, Singapore, 2002, 269-292.
    (PostScript file of preprint available).
32. (CMUP 2001-24).
    Jorge Almeida and Manuel Delgado, Tameness of the pseudovariety of abelian groups
    Published in Int. J. Algebra Comput. 15 (2005) 327-338.
    (PostScript file of preprint available).
33. (CMUP 2002-01).
    Jorge Almeida, Finite semigroups: an introduction to a unified theory of pseudovarieties.
    In G. M. S. Gomes, J.-E. Pin and P. V. Silva (eds.), Semigroups, Algorithms, Automata and Languages, World Scientific, Singapore, 2002, 3-64.
    (PostScript file of preprint available).
34. (CMUP 2002-33).
    Jorge Almeida and Mikhail V. Volkov, Profinite identities for finite semigroups whose subgroups belong to a given pseudovariety.
    J. Algebra & Applications 2 (2003) 137-163.
    (PDF file of preprint available).
35. (CMUP 2003-03).
    Jorge Almeida and Ana Escada, The globals of some subpseudovarieties of DA.
    Published in Int. J. Algebra Comput. 14 (2004) 525-549.
    (PDF file of preprint available).
36. (CMUP 2003-05).
    Jorge Almeida, Symbolic dynamics in free profinite semigroups.
    Proceedings of the Symposium "Algebraic Systems, Formal Languages and, Conventional and Unconventional Computation Theory" (Sept. 24-26, 2002)
    RIMS Kokyuroku 1366 (2004) 1-12. (Research Institute for Mathematical Sciences, Kyoto University, Kyoto, Japan)
    ( revised PDF file available).
37. (CMUP 2003-11).
    Jorge Almeida and M. V. Volkov, Subword complexity of profinite words and subgroups of free profinite semigroups.
    Published in Int. J. Algebra Comput. 16 (2006) 221-258.
    (PDF file available).
38. Jorge Almeida, Profinite structures and dynamics. Published in CIM Bulletin 14 (2003) 8-18.
    (PDF file available).
39. (CMUP 2003-23).
    Jorge Almeida and M. Zeitoun, The equational theory of ω-terms for finite R-trivial semigroups.
    Proceedings of the Workshop on Semigroups and Languages (Lisbon 2002, I. M. Araújo, M. J. J. Branco, V. H. Fernandes, G. M. S. Gomes, eds.), World Scientific, 2004, 1-22.
    (PDF file of preprint available).
40. (CMUP 2003-33) Jorge Almeida, Profinite semigroups and applications.
    Published in V. Kudryavtsev, I. G. Rosenberg (Eds.), Structural Theory of Automata, Semigroups, and Universal Algebra, Proceedings of NATO Advanced Study Institute, Montréal, Québec, Canada, 7-18/7/2003. NATO Science Series II: Mathematics, Physics and Chemistry, Vol. 207, Springer, 2005, 1-45.
    (revised PDF file of preprint available).
41. (CMUP 2004-09) J. Almeida, S. W. Margolis, M. V. Volkov, The pseudovariety of semigroups of triangular matrices over a finite field.
    Published in Theor. Informatics Appl. (special issue in honour of Imre Simon's 60th birthday) 39 (2005) 31-48.
    (PDF file of preprint available).
42. (CMUP 2004-18) J. Almeida, A. Escada, The globals of pseudovarieties of ordered semigroups containing B₂ and an application to a problem proposed by Pin.
    Published in Theor. Informatics Appl. (special issue in honour of Imre Simon's 60th birthday) 39 (2005) 1-29.
    (PDF file of preprint available).
43. (CMUP 2004-21) J. Almeida, J. C. Costa, M. Zeitoun, Tameness of pseudovariety joins involving R.
    (revised PDF file of preprint available).
    Published in Monatsh. Math. 146 (2005) 89-111.
44. (CMUP 2004-38) J. Almeida and M. Zeitoun, An automata-theoretic approach to the word problem for ω-terms over R
    (PDF file of revised version available).
    Published in Theor. Comp. Sci. 370 (2007) 131-169.
45. (CMUP 2005-01) J. Almeida, Profinite groups associated with weakly primitive substitutions
    (revised PDF file of preprint available).
    Published in Russian in the journal "Fundamentalnaya i Prikladnaya Matematika" (Fundamental and Applied Mathematics) 11-3 (2005) 13-48,
    with PDF file English version in J. Mathematical Sciences 144-2 (2007) 3881-3903.
46. (CMUP 2005-02) J. Almeida, O grupo profinito de uma substituição primitiva
    Published in Actas do Encontro de Algebristas Portugueses/2004, Universidade de Trás-os-Montes e Alto Douro, 2005, 1-13.
    (PDF file of preprint available).
47. (CMUP 2005-26) J. Almeida, S. W. Margolis, B. Steinberg, and M. V. Volkov, Modular and threshold subword counting and matrix representations of finite monoids
    (PDF file available).
48. (CMUP 2005-41) J. Almeida, Engel elements in groups and dynamical systems defining nilpotency in finite groups
    (PDF file available).
49. (CMUP 2006-19) J. Almeida, J. C. Costa, M. Zeitoun, Complete reducibility of pseudovarieties
    Published in Proceedings of the International Conference Semigroups and Formal Languages in honour of D. McAlister (Lisbon, July, 2005), (Jorge M. André, Mário J. J. Branco, Vítor H. Fernandes, John Fountain, Gracinda M. S. Gomes and John C. Meakin, eds.), World Scientific, 2007, 9-25.
    (PDF file of preprint available).
50. (CMUP 2006-20) J. Almeida, S. W. Margolis, B. Steinberg and M. V. Volkov, Representation theory of finite semigroups, semigroup radicals and formal language theory
    (PDF file available).
    Published in the Trans. Amer. Math. Soc. 361 (2009) 1429-1461.
51. (CMUP 2006-31) J. Almeida, J. C. Costa, M. Zeitoun, Complete reducibility of systems of equations with respect to R
    (PDF file available).
    Published in Portugaliae Mathematica 64 (2007) 445-508.
52. (CMUP 2006-39) J. Almeida, M. Zeitoun, A bottom-up minimization DFA algorithm and applications
    Published in Inform. Process. Lett. 107 (2008) 52-59, under the title Description and analysis of a bottom-up DFA minimization algorithm.
    (PDF file of revised version available).
53. (CMUP 2006-44) J. Almeida, J. C. Costa, M. Zeitoun, Pointlike sets with respect to R and J
    Published in J. Pure and Applied Algebra 212 (2008) 486-499.
    (PDF file of preprint available).
54. (CMUP 2007-19) J. Almeida, M. V. Volkov, S. V. Goldberg, Complexity of the identity checking problem for finite semigroups
    (PDF file of revised version available).
    Published, in Russian, in Zapiski Nauchnykh Seminarov Sankt-Peterburgskogo Otdeleniya Matematicheskogo Instituta imeni V. A. Steklova Rossiiskoi Akademii Nauk (Notes of Scientific Seminars of the St Petersburg Department of the Steklov Mathematical Institute, Russian Academy of Sciences) 358 (2008) "Studies in Constructive Mathematics and Mathematical Logic. Part XI", 5-22.
    Published also in English, in J. Math. Sci. 158 (2009) 605-614.
55. (CMUP 2007-20) J. Almeida, A. Costa, Infinite-vertex free profinite semigroupoids and symbolic dynamics
    Published in J. Pure Appl. Algebra 213 (2009) 605-631.
    (PDF file of revised version of preprint available).
56. (CMUP 2007-35) J. Almeida, Decidability and tameness in the theory of finite semigroups
    Published in Bull. Iranian Math. Soc. 34 (2008) 1-22.
    (PDF file of preprint).
57. (CMUP 2008-21) J. Almeida, B. Steinberg, Rational codes and free profinite monoids
    Published in J. London Math. Soc. (2) 79 (2009) 465-477.
    (PDF file of preprint available).
58. (CMUP 2009-3) J. Almeida, J. C. Costa, M. Zeitoun, Iterated periodicity over finite aperiodic semigroups
    (PDF file of preprint available).
    Published in Europ. J. Combin. 37 (2014) 115-149
59. (CMUP 2009-13) J. Almeida, B. Steinberg, Matrix mortality and the Černý-Pin conjecture
    Published in Diekert, Volker (ed.) et al., Developments in language theory. 13th international conference, DLT 2009, Stuttgart, Germany, June 30-July 3, 2009. Proceedings. Berlin: Springer. Lecture Notes in Computer Science 5583, 67-80 (2009).
    (PDF file of preprint available).
60. (CMUP 2009-14) J. Almeida, J. C. Costa, M. Zeitoun, Some structural properties of the free profinite aperiodic semigroup
    (PDF file available).
61. (CMUP 2009-17) J. Almeida, O. Klíma, A counterexample to some conjectures concerning concatenation hierarchies
    ( revised PDF file available, with the new title A counterexample to a conjecture concerning concatenation hierarchies).
    Published in Information Processing Letters 110 (2009) 4-7 (DOI: 10.1016/j.ipl.2009.09.011).
62. (CMUP 2009-28) J. Almeida, J. C. Costa, M. L. Teixeira, Semidirect product with an order-computable pseudovariety and tameness
    (PDF file of revised version of preprint available).
    Published in special issue of Semigroup Forum dedicated to the memory of W. D. Munn. Semigroup Forum 81 (2010) 26-50 (DOI: 10.1007/s00233-010-9236-z).
63. (CMUP 2009-29) J. Almeida, S. Margolis, B. Steinberg, M. Volkov, Characterization of group radicals with an application to Mal'cev products
    (PDF file of preprint available).
    Published in Illinois J. Math. 54 (2010) 199-221.
64. (CMUP 2009-39) J. Almeida, O. Klíma, New decidable upper bound of the second level in the Straubing-Thérien concatenation hierarchy of star-free languages
    ( PDF file of revised version available).
    Published in Discr. Math. & Theor. Comp. Sci. 12 (2010) 41-58.
65. (CMUP 2009-42) J. Almeida, A. Moura, Idempotent-generated semigroups and pseudovarieties
    Published in Proc. Edinburgh Math. Soc. 54 (2011) 545-568.
    (The pdf file of the published paper is made available here under permission of the copyright holder, The Edinburgh Mathematical Society.)
    (DOI:10.1017/S0013091509001795).
66. (CMUP 2010-1) J. Almeida, A. Costa, Presentations of Schützenberger groups of minimal subshifts
    (PDF file of third version available).
    Published in Israel J. Math. 196 (2013), 1-31 (DOI: 10.1007/s11856-012-0139-4).
67. (CMUP 2011-23) J. Almeida, A. Costa, On the transition semigroups of centrally labeled Rauzy graphs
    ( PDF file of preprint available).
    Published in Int. J. Algebra and Comput. 22 (2012) 1250018
68. (CMUP 2011-33) J. Almeida, O. Klíma, On the irreducibility of pseudovarieties of semigroups
    (PDF file of preprint available).
    Published in J. Pure Appl. Algebra 220 (2016) 1517-1524
69. (CMUP 2012-3) J. Almeida, J. C. Costa, M. Zeitoun, McCammond's normal forms for free aperiodic semigroups revisited
    (PDF file of preprint available).
    Published in LMS J. Comput. Math. 18 (2015) 130-147
70. (CMUP 2012-26) J. Almeida, A. Cardoso, A sequence of weakly monotonic automata with increasing level
    (PDF file of preprint available).
    Published in Int. J. Algebra 7 (2013) 91-100
71. J. Almeida, M. Couceiro, T. Waldhauser, On the topological semigroup of equational classes of finite functions under composition
    (PDF file of preprint available).
    Published in J. Mult.-Valued Logic Soft Comput. 28 (2017) 5-28

WARNING!

Notes:

• If some specific link does not work, please contact me at the above email address.