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3.0

Jun 30, 2018
06/18

by
Jorge Almeida; José Carlos Costa; Marc Zeitoun

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This paper revisits the solution of the word problem for $\omega$-terms interpreted over finite aperiodic semigroups, obtained by J. McCammond. The original proof of correctness of McCammond's algorithm, based on normal forms for such terms, uses McCammond's solution of the word problem for certain Burnside semigroups. In this paper, we establish a new, simpler, correctness proof of McCammond's algorithm, based on properties of certain regular languages associated with the normal forms. This...

Topics: Computing Research Repository, Formal Languages and Automata Theory

Source: http://arxiv.org/abs/1406.0888

2
2.0

Jun 28, 2018
06/18

by
Jorge Almeida; Célia Borlido

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We denote by kappa the implicit signature that contains the multiplication and the (omega-1)-power. It is proved that for any completely kappa-reducible pseudovariety of groups H, the pseudovariety DRH of all finite semigroups whose regular R-classes are groups in H is completely kappa-reducible as well. The converse also holds. The tools used by Almeida, Costa, and Zeitoun for proving that the pseudovariety of all finite R-trivial monoids is completely kappa-reducible are adapted for the...

Topics: Group Theory, Mathematics

Source: http://arxiv.org/abs/1512.01024

2
2.0

Jun 30, 2018
06/18

by
Jorge Almeida; Zoltán Ésik; Jean-Éric Pin

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We study the commutative positive varieties of languages closed under various operations: shuffle, renaming and product over one-letter alphabets.

Topics: Group Theory, Formal Languages and Automata Theory, Computing Research Repository, Mathematics

Source: http://arxiv.org/abs/1703.02154

2
2.0

Jun 29, 2018
06/18

by
Jorge Almeida; Alfredo Costa

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We give a complete characterization of pseudovarieties of semigroups whose finitely generated relatively free profinite semigroups are equidivisible. Besides the pseudovarieties of completely simple semigroups, they are precisely the pseudovarieties that are closed under Mal'cev product on the left by the pseudovariety of locally trivial semigroups. A further characterization which turns out to be instrumental is as the non-completely simple pseudovarieties that are closed under two-sided...

Topics: Group Theory, Mathematics

Source: http://arxiv.org/abs/1603.00330

2
2.0

Jun 30, 2018
06/18

by
Jorge Almeida; Alfredo Costa; José Carlos Costa; Marc Zeitoun

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Given a pseudoword over suitable pseudovarieties, we associate to it a labeled linear order determined by the factorizations of the pseudoword. We show that, in the case of the pseudovariety of aperiodic finite semigroups, the pseudoword can be recovered from the labeled linear order.

Topics: Group Theory, Formal Languages and Automata Theory, Computing Research Repository, Mathematics

Source: http://arxiv.org/abs/1702.08083

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45

Sep 22, 2013
09/13

by
Jorge Almeida; Alfredo Costa

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In previous work, the first author established a natural bijection between minimal subshifts and maximal regular J-classes of free profinite semigroups. In this paper, the Sch\"utzenberger groups of such J-classes are investigated, in particular in respect to a conjecture proposed by the first author concerning their profinite presentation. The conjecture is established for all non-periodic minimal subshifts associated with substitutions. It entails that it is decidable whether a finite...

Source: http://arxiv.org/abs/1001.1475v3

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97

Sep 22, 2013
09/13

by
Jorge Almeida; Stuart Margolis; Benjamin Steinberg; Mikhail Volkov

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In this paper we characterize the congruence associated to the direct sum of all irreducible representations of a finite semigroup over an arbitrary field, generalizing results of Rhodes for the field of complex numbers. Applications are given to obtain many new results, as well as easier proofs of several results in the literature, involving: triangularizability of finite semigroups; which semigroups have (split) basic semigroup algebras, two-sided semidirect product decompositions of finite...

Source: http://arxiv.org/abs/math/0702400v1

3
3.0

Apr 8, 2021
04/21

by
Jorge Almeida (Kenxiro)

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Customized version of http://www.thingiverse.com/thing:74322 Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=74322

Topics: stl, thingiverse, 2D Art, customized

3
3.0

Apr 22, 2021
04/21

by
Jorge Almeida (Kenxiro)

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Customized version of http://www.thingiverse.com/thing:16627 Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=16627

Topics: stl, 3D Printer Parts, customized, thingiverse

0
0.0

Aug 30, 2021
08/21

by
Shan Xu; Jorge Almeida; Dietmar Heinke

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Source: https://osf.io/4t3dw/

1
1.0

Apr 12, 2021
04/21

by
Jorge Almeida (Kenxiro)

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Customized version of http://www.thingiverse.com/thing:175150 Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=175150

Topics: thingiverse, stl, Organization, customized

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44

Oct 24, 2014
10/14

by
Thompson, Claudia Elizabeth; Beys-da-Silva, Walter Orlando; Santi, Lucelia; Berger, Markus; Vainstein, Marilene Henning; Guima raes, Jorge Almeida; Vasconcelos, Ana Tereza Ribeiro

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This article is from AMB Express , volume 3 . Abstract The mangroves are among the most productive and biologically important environments. The possible presence of cellulolytic enzymes and microorganisms useful for biomass degradation as well as taxonomic and functional aspects of two Brazilian mangroves were evaluated using cultivation and metagenomic approaches. From a total of 296 microorganisms with visual differences in colony morphology and growth (including bacteria, yeast and...

Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3922913