Research articles of Valdis Laan
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V. Laan, On a generalization of strong flatness, Acta Comment. Univ.
Tartuensis, no. 2 (1998), 55-60. (pdf)
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V. Laan, On classification of monoids by properties of cofree acts,
Semigroup Forum, no. 59 (1999), 79-92.
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V. Laan, When torsion free acts are principally weakly flat, Semigroup
Forum, no. 60 (2000), 321-325.
(link)
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M. Kilp and V. Laan, On flatness properties of cyclic acts, Communications
in Algebra, no. 28 (2000), 2919-2926.
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V. Laan, Pullbacks and flatness properties of acts I, Communications
in Algebra, no. 29 (2) (2001), 829-850.
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S. Bulman-Fleming, M. Kilp and V. Laan, Pullbacks and flatness properties
of acts II, Communications in Algebra, no. 29 (2) (2001), 851-878.
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S. Bulman-Fleming and V. Laan, Tensor products and preservation of limits,
for acts over monoids, Semigroup Forum, no. 63 (2001), 161-179.
(link)
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V. Laan, On Descent Theory for Monoid Actions,
Applied Categorical Structures, no. 12 (5-6) (2004), 479-483.
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H. Oltmanns, U. Knauer, V. Laan and M. Kilp On (B,B)-projectivity,
in: "Categorical Structures and their Applications. Proceedings of
the North-West European Category Seminar, Berlin, Germany, 28-29 March 2003",
World Scientific, Singapore, 2004, pp. 219-226.
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V. Laan, Wreath product of set-valued functors and tensor
multiplication, Semigroup Forum, no. 70 (2005), 188-207.
(link)
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S. Bulman-Fleming, V. Laan, Lazard's Theorem for S-posets,
Math. Nachr., no. 278 (15) (2005), 1743-1755.
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X. Zhang, V. Laan, On homological classification of pomonoids
by regular weak injectivity properties of S-posets,
Cent. Eur. J. Math., no. 5(1) (2007), 181-200. Corrigendum.
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V. Laan, P. Penjam, On descent theory for distributors,
Acta Comment. Univ. Tartuensis Math., no. 11 (2007), 13-22.
(pdf)
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G. Janelidze, V. Laan, L. Márki, Limit preservation properties
of the greatest semilattice functor, Internat. J. Algebra Comput.,
no. 18(5) (2008), 853-867.
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V. Laan, Generators in the category of S-posets,
Cent. Eur. J. Math., no. 6(3) (2008), 357-363.
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V. Laan, Context equivalence of semigroups,
Period. Math. Hung., no. 60(1) (2010), 81-94.
(link)
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V. Laan, Tensor products and preservation of weighted limits,
for S-posets, Comm. Algebra, no. 38(11) (2010), 4322-4332.
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V. Laan, L. Márki, Strong Morita equivalence of semigroups with
local units, J. Pure Appl. Algebra, no. 215(10) (2011), 2538-2546.
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V. Laan, Morita theorems for partially ordered monoids,
Proc. Est. Acad. Sci., no. 60(4) (2011), 221-237.
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V. Laan, L. Márki, Morita invariants for semigroups with local
units, Monatsh. Math., no. 166(3) (2012), 441-451.
DOI: 10.1007/s00605-010-0279-8.
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V. Laan, Acceptable Morita contexts for semigroups, ISRN Algebra,
vol. 2012, article ID 725627, 2012, 5 pages.
DOI:10.5402/2012/725627.
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T. Tärgla, V. Laan, Congruences of strongly Morita equivalent
posemigroups, Acta Math. Univ. Comenian. (N.S.), no. 81(2) (2012),
247-254.
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M. Sedaghatjoo, V. Laan, M. Ershad Principal weak flatness and regularity
of diagonal acts, Communications in Algebra, no. 40 (11) (2012),
4019-4030.
DOI:10.1080/00927872.2011.600747
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V. Laan, Congruences of Morita equivalent small categories,
Theory Appl. Categ., no. 26 (2012), 331-337.
(pdf)
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V. Laan, On Morita equivalence of partially ordered monoids,
Appl. Categ. Structures, no. 22 (2014), 137-146.
DOI: 10.1007/s10485-013-9305-z
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X. Zhang, V. Laan, Injective hulls for posemigroups,
Proc. Est. Acad. Sci., no. 63 (2014), 372-378.
(pdf)
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V. Laan, N. Sohail, On mono- and epimorphisms in varieties of ordered
algebras, Comm. Algebra., no. 43 (2015), 2802-2819.
DOI:10.1080/00927872.2014.904328
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X. Zhang, V. Laan, On injective hulls of S-posets,
Semigroup Forum, no. 91 (2015), 62-70.
DOI: 10.1007/s00233-014-9646-4 .
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V. Laan, S. Nasir, L. Tart, On congruence extension properties
for ordered algebras, Period. Math. Hung., no. 71 (2015), 92-111.
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X. Zhang, V. Laan, Quotients and subalgebras of sup-algebras,
Proc. Est. Acad. Sci., no. 64 (2015), 311-322.
(pdf)
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V. Laan, L. Márki, Fair semigroups and Morita equivalence,
Semigroup Forum, no. 92 (2016), 633-644.
DOI: 10.1007/s00233-015-9723-3.
(link)
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X. Zhang, V. Laan, Injective hulls for ordered algebras,
Algebra Universalis, no. 76 (2016), 339-349.
DOI: 10.1007/s00012-016-0404-1.
(link)
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V. Laan, N. Sohail, L. Tart, Hamiltonian ordered algebras and congruence
extension, Math. Slovaca 67 (2017), 819-830.
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X. Liang, V. Laan, Y. Luo, R. Khosravi,
Weakly torsion free S-posets, Comm. Algebra 45 (2017), 3340-3352.
(pdf)
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V. Laan, L. Márki, Ü. Reimaa, Morita equivalence
of semigroups revisited: firm semigroups,
J. Algebra 505 (2018), 247-270.
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V. Laan, Ü. Reimaa, Monomorphisms in categories of
firm acts, Studia Sci. Math. Hungar. 56 (2019), 267-279.
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V. Laan, Ü. Reimaa, Morita equivalence of factorizable
semigroups, Internat. J. Algebra Comput. 29 (2019), 723-741.
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V. Laan, L. Márki, Ü. Reimaa, Lattices and quantales of
ideals of semigroups and their preservation under Morita contexts,
Algebra Univers. 81, 24 (2020).
(link)
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V. Laan, K. Väljako, Enlargements of rings, Comm. Algebra 49
(2021), 1764-1772.
(free e-print)
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Ü. Reimaa, V. Laan, L. Tart, Morita equivalence of finite
semigroups, Semigroup Forum 102 (2021), 842-860.
(pdf)
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V. Laan, Ü. Reimaa, L. Tart, E. Teor, Flatness properties of
acts over semigroups, Categ. Gen. Algebr. Struct. Appl. 15 (2021),
59-92.
(pdf)
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K. Väljako, V. Laan, Morita contexts and unitary ideals of rings,
Proc. Est. Acad. Sci. 70 (2021), 122-134. (pdf)
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X. Zhang, V. Laan, J. Feng, Ü. Reimaa, Correction to: Injective hulls for
ordered algebras, Algebra Universalis 82, 65 (2021).
(link)
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X. Zhang, V. Laan, J. Feng, Injective hulls are completions of ordered
algebras, Order, published online on August 03, 2023.
(link)
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G. Kudryavtseva, V. Laan, Proper Ehresmann semigroups, Proc.
Edinburgh Math. Soc. 66 (2023), 758-788. (link)
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V. Laan, A. Lepik, Perfection for semigroups, Proc. Edinburgh Math.
Soc. 66 (2023), 259-287.
DOI: 10.1017/S0013091523000159
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G. Kudryavtseva, V. Laan, Globalization of partial actions of
semigroups, Semigroup Forum 107 (2023), 200-217.
(link)
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V. Laan, J. Feng, X. Zhang, Admissible subsets and completions of ordered
algebras, Algebra Universalis 84:19 (2023).
DOI:10.1007/s00012-023-00813-9
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L. Marín, V. Laan, Firm homomorphisms of rings and semigroups,
Theory Appl. Categ. 39 (2023), 625-666.
(link)
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M. Kutti, V. Laan, Idempotent 2 × 2 matrices over linearly ordered
abelian groups, Categ. Gen. Algebr. Struct. Appl., published online 30.10.2023.
(link)
My PhD thesis can be found here.
If you wish to have an electronic copy of any of these articles, please send
an e-mail to: vlaan at ut dot ee .