Konieczny, Janusz Normal subsemigroups of finite transformation semigroups. (English) Zbl 07785784 Semigroup Forum 107, No. 3, 680-691 (2023). MSC: 20M20 03Dxx 05Cxx PDFBibTeX XMLCite \textit{J. Konieczny}, Semigroup Forum 107, No. 3, 680--691 (2023; Zbl 07785784) Full Text: DOI
Araújo, João; Bentz, Wolfram; Cameron, Peter J.; Kinyon, Michael; Konieczny, Janusz Matrix theory for independence algebras. (English) Zbl 07518022 Linear Algebra Appl. 642, 221-250 (2022). MSC: 08A35 20M20 PDFBibTeX XMLCite \textit{J. Araújo} et al., Linear Algebra Appl. 642, 221--250 (2022; Zbl 07518022) Full Text: DOI
Konieczny, Janusz Semigroups of transformations whose restrictions belong to a given semigroup. (English) Zbl 1515.20303 Semigroup Forum 104, No. 1, 109-124 (2022). MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny}, Semigroup Forum 104, No. 1, 109--124 (2022; Zbl 1515.20303) Full Text: DOI
Konieczny, Janusz Corrigendum to: “Second centralizers in the semigroup of injective transformations”. (English) Zbl 1491.20130 Asian-Eur. J. Math. 14, No. 9, Article ID 2192001, 2 p. (2021). MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny}, Asian-Eur. J. Math. 14, No. 9, Article ID 2192001, 2 p. (2021; Zbl 1491.20130) Full Text: DOI
André, Jorge; Konieczny, Janusz Semigroups of partial transformations with kernel and image restricted by an equivalence. (English) Zbl 1477.20121 Semigroup Forum 102, No. 1, 10-27 (2021). Reviewer: Ronnason Chinram (Hat Yai) MSC: 20M20 20M12 20M17 PDFBibTeX XMLCite \textit{J. André} and \textit{J. Konieczny}, Semigroup Forum 102, No. 1, 10--27 (2021; Zbl 1477.20121) Full Text: DOI Link
Konieczny, Janusz The structure of centralizers in the finite symmetric inverse semigroup. (English) Zbl 1472.20139 Commun. Algebra 48, No. 12, 5181-5194 (2020). Reviewer: Ilinka Dimitrova (Blagoevgrad) MSC: 20M20 20M18 PDFBibTeX XMLCite \textit{J. Konieczny}, Commun. Algebra 48, No. 12, 5181--5194 (2020; Zbl 1472.20139) Full Text: DOI
Konieczny, Janusz Second centralizers in the semigroup of injective transformations. (English) Zbl 1443.20089 Asian-Eur. J. Math. 13, No. 4, Article ID 2050069, 11 p. (2020); corrigendum ibid. 14, No. 9, Article ID 2192001, 2 p. (2021). Reviewer: Ronnason Chinram (Hat Yai) MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny}, Asian-Eur. J. Math. 13, No. 4, Article ID 2050069, 11 p. (2020; Zbl 1443.20089) Full Text: DOI
Araújo, João; Kinyon, Michael; Konieczny, Janusz Conjugacy in inverse semigroups. (English) Zbl 1446.20079 J. Algebra 533, 142-173 (2019). Reviewer: Peter R. Jones (Milwaukee) MSC: 20M18 20M10 20M05 20M20 PDFBibTeX XMLCite \textit{J. Araújo} et al., J. Algebra 533, 142--173 (2019; Zbl 1446.20079) Full Text: DOI arXiv Link
Konieczny, Janusz The semigroup of surjective transformations on an infinite set. (English) Zbl 1490.20041 Algebra Colloq. 26, No. 1, 9-22 (2019). MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny}, Algebra Colloq. 26, No. 1, 9--22 (2019; Zbl 1490.20041) Full Text: DOI
Konieczny, Janusz Centralizers of full injective transformations in the symmetric inverse semigroup. (English) Zbl 1435.20071 Semigroup Forum 96, No. 3, 474-488 (2018). Reviewer: Gracinda M. S. Gomes (Lisboa) MSC: 20M18 20M20 20M15 PDFBibTeX XMLCite \textit{J. Konieczny}, Semigroup Forum 96, No. 3, 474--488 (2018; Zbl 1435.20071) Full Text: DOI
Araújo, João; Kinyon, Michael; Konieczny, Janusz; Malheiro, António Decidability and independence of conjugacy problems in finitely presented monoids. (English) Zbl 1435.20064 Theor. Comput. Sci. 731, 88-98 (2018). MSC: 20M05 03D40 20M35 PDFBibTeX XMLCite \textit{J. Araújo} et al., Theor. Comput. Sci. 731, 88--98 (2018; Zbl 1435.20064) Full Text: DOI arXiv
Araújo, João; Bentz, Wolfram; Dobson, Edward; Konieczny, Janusz; Morris, Joy Automorphism groups of circulant digraphs with applications to semigroup theory. (English) Zbl 1399.05099 Combinatorica 38, No. 1, 1-28 (2018). MSC: 05C25 20M20 20B25 05C20 PDFBibTeX XMLCite \textit{J. Araújo} et al., Combinatorica 38, No. 1, 1--28 (2018; Zbl 1399.05099) Full Text: DOI Link
Konieczny, Janusz A new definition of conjugacy for semigroups. (English) Zbl 1481.20205 J. Algebra Appl. 17, No. 2, Article ID 1850032, 20 p. (2018). MSC: 20M10 20M20 20M15 05C20 PDFBibTeX XMLCite \textit{J. Konieczny}, J. Algebra Appl. 17, No. 2, Article ID 1850032, 20 p. (2018; Zbl 1481.20205) Full Text: DOI
Araújo, João; Kinyon, Michael; Konieczny, Janusz; Malheiro, António Four notions of conjugacy for abstract semigroups. (English) Zbl 1486.20071 Proc. R. Soc. Edinb., Sect. A, Math. 147, No. 6, 1169-1214 (2017). MSC: 20M07 20M20 20M15 PDFBibTeX XMLCite \textit{J. Araújo} et al., Proc. R. Soc. Edinb., Sect. A, Math. 147, No. 6, 1169--1214 (2017; Zbl 1486.20071) Full Text: DOI arXiv
Araújo, João; Bentz, Wolfram; Konieczny, Janusz Directed graphs of inner translations of semigroups. (English) Zbl 1423.05078 Semigroup Forum 94, No. 3, 650-673 (2017). MSC: 05C25 20M20 20M15 05C20 PDFBibTeX XMLCite \textit{J. Araújo} et al., Semigroup Forum 94, No. 3, 650--673 (2017; Zbl 1423.05078) Full Text: DOI Link
Araújo, João; Konieczny, Janusz; Malheiro, António Conjugation in semigroups. (English) Zbl 1302.20065 J. Algebra 403, 93-134 (2014). Reviewer: Volodymyr Mazorchuk (Uppsala) MSC: 20M20 20M10 PDFBibTeX XMLCite \textit{J. Araújo} et al., J. Algebra 403, 93--134 (2014; Zbl 1302.20065) Full Text: DOI arXiv
Araújo, João; Bentz, Wolfram; Konieczny, Janusz The largest subsemilattices of the endomorphism monoid of an independence algebra. (English) Zbl 1302.08005 Linear Algebra Appl. 458, 60-79 (2014). Reviewer: Václav Koubek (Praha) MSC: 08A35 20M20 20M15 PDFBibTeX XMLCite \textit{J. Araújo} et al., Linear Algebra Appl. 458, 60--79 (2014; Zbl 1302.08005) Full Text: DOI arXiv
Konieczny, Janusz Automorphism groups of endomorphism monoids of free \(G\)-sets. (English) Zbl 1301.20064 Asian-Eur. J. Math. 7, No. 1, Article ID 1450015, 15 p. (2014). Reviewer: Peeter Normak (Tallinn) MSC: 20M20 08A35 08B20 20M15 PDFBibTeX XMLCite \textit{J. Konieczny}, Asian-Eur. J. Math. 7, No. 1, Article ID 1450015, 15 p. (2014; Zbl 1301.20064) Full Text: DOI
Konieczny, Janusz Centralisers in the infinite symmetric inverse semigroup. (English) Zbl 1273.20066 Bull. Aust. Math. Soc. 87, No. 3, 462-479 (2013). Reviewer: Volodymyr Mazorchuk (Uppsala) MSC: 20M20 20M18 PDFBibTeX XMLCite \textit{J. Konieczny}, Bull. Aust. Math. Soc. 87, No. 3, 462--479 (2013; Zbl 1273.20066) Full Text: DOI
Araújo, João; Konieczny, Janusz Centralizers in the full transformation semigroup. (English) Zbl 1267.20090 Semigroup Forum 86, No. 1, 1-31 (2013). Reviewer: Volodymyr Mazorchuk (Uppsala) MSC: 20M20 PDFBibTeX XMLCite \textit{J. Araújo} and \textit{J. Konieczny}, Semigroup Forum 86, No. 1, 1--31 (2013; Zbl 1267.20090) Full Text: DOI Link
Droms, Sean V.; Konieczny, Janusz; Palomba, Roberto \(S_n\)-normal semigroups of partial transformations. (English) Zbl 1298.20075 Algebra Colloq. 19, Spec. Iss. 1, 947-970 (2012). MSC: 20M20 20M15 PDFBibTeX XMLCite \textit{S. V. Droms} et al., Algebra Colloq. 19, 947--970 (2012; Zbl 1298.20075) Full Text: DOI
Araújo, João; Konieczny, Janusz A method for finding new sets of axioms for classes of semigroups. (English) Zbl 1262.20059 Arch. Math. Logic 51, No. 5-6, 461-474 (2012). Reviewer: Pedro Sánchez Terraf (Córdoba) MSC: 20M07 20N02 20A05 08B05 20M20 08A02 03C05 20M10 PDFBibTeX XMLCite \textit{J. Araújo} and \textit{J. Konieczny}, Arch. Math. Logic 51, No. 5--6, 461--474 (2012; Zbl 1262.20059) Full Text: DOI Link
Konieczny, Janusz A proof of Devadze’s theorem on generators of the semigroup of Boolean matrices. (English) Zbl 1238.20069 Semigroup Forum 83, No. 2, 281-288 (2011). MSC: 20M20 20M05 PDFBibTeX XMLCite \textit{J. Konieczny}, Semigroup Forum 83, No. 2, 281--288 (2011; Zbl 1238.20069) Full Text: DOI
André, Jorge; Araújo, João; Konieczny, Janusz Regular centralizers of idempotent transformations. (English) Zbl 1227.20054 Semigroup Forum 82, No. 2, 307-318 (2011). Reviewer: G. I. Zhitomirskij (Herzliyya) MSC: 20M20 20M05 20M17 PDFBibTeX XMLCite \textit{J. André} et al., Semigroup Forum 82, No. 2, 307--318 (2011; Zbl 1227.20054) Full Text: DOI Link
Konieczny, Janusz Infinite injective transformations whose centralizers have simple structure. (English) Zbl 1214.20057 Cent. Eur. J. Math. 9, No. 1, 23-35 (2011). MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny}, Cent. Eur. J. Math. 9, No. 1, 23--35 (2011; Zbl 1214.20057) Full Text: DOI
Araújo, João; Kinyon, Michael; Konieczny, Janusz Minimal paths in the commuting graphs of semigroups. (English) Zbl 1227.05161 Eur. J. Comb. 32, No. 2, 178-197 (2011). MSC: 05C25 20M20 05C38 05C35 PDFBibTeX XMLCite \textit{J. Araújo} et al., Eur. J. Comb. 32, No. 2, 178--197 (2011; Zbl 1227.05161) Full Text: DOI arXiv
Konieczny, Janusz Centralizers in the semigroup of injective transformations on an infinite set. (English) Zbl 1205.20063 Bull. Aust. Math. Soc. 82, No. 2, 305-321 (2010). Reviewer: Volodymyr Mazorchuk (Uppsala) MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny}, Bull. Aust. Math. Soc. 82, No. 2, 305--321 (2010; Zbl 1205.20063) Full Text: DOI
Araújo, João; Dobson, Edward; Konieczny, Janusz Automorphisms of endomorphism semigroups of reflexive digraphs. (English) Zbl 1208.20055 Math. Nachr. 283, No. 7, 939-964 (2010). Reviewer: Peeter Normak (Tallinn) MSC: 20M20 05C20 20M15 05C25 PDFBibTeX XMLCite \textit{J. Araújo} et al., Math. Nachr. 283, No. 7, 939--964 (2010; Zbl 1208.20055) Full Text: DOI
Araújo, João; Konieczny, Janusz The Largest Subsemilattices of the Semigroup of Transformations on a Finite Set. arXiv:1007.4845 Preprint, arXiv:1007.4845 [math.GR] (2010). MSC: 20M20 06A12 BibTeX Cite \textit{J. Araújo} and \textit{J. Konieczny}, ``The Largest Subsemilattices of the Semigroup of Transformations on a Finite Set'', Preprint, arXiv:1007.4845 [math.GR] (2010) Full Text: arXiv OA License
Araújo, João; Konieczny, Janusz General theorems on automorphisms of semigroups and their applications. (English) Zbl 1194.20059 J. Aust. Math. Soc. 87, No. 1, 1-17 (2009). Reviewer: Heinz Mitsch (Wien) MSC: 20M15 20M30 08A35 20F29 PDFBibTeX XMLCite \textit{J. Araújo} and \textit{J. Konieczny}, J. Aust. Math. Soc. 87, No. 1, 1--17 (2009; Zbl 1194.20059) Full Text: DOI
Araújo, João; Konieczny, Janusz Automorphisms of endomorphism monoids of 1-simple free algebras. (English) Zbl 1168.08001 Commun. Algebra 37, No. 1, 83-94 (2009). Reviewer: G. I. Zhitomirskij (Herzliyya) MSC: 08A35 08B20 20M20 PDFBibTeX XMLCite \textit{J. Araújo} and \textit{J. Konieczny}, Commun. Algebra 37, No. 1, 83--94 (2009; Zbl 1168.08001) Full Text: DOI
Araújo, João; Konieczny, Janusz The monoid of holomorphic endomorphisms of a group and its automorphisms. (English) Zbl 1189.20062 Laan, Valdis (ed.) et al., Proceedings of the international conference on semigroups, acts and categories with applications to graphs to celebrate the 65th birthdays of Mati Kilp and Ulrich Knauer, Tartu, Estonia, June 27–30, 2007. Tartu: Estonian Mathematical Society (ISBN 978-9985-9644-2-2/pbk). Mathematics Studies (Tartu) 3, 7-13 (2008). MSC: 20M20 20M15 PDFBibTeX XMLCite \textit{J. Araújo} and \textit{J. Konieczny}, Math. Stud., Tartu 3, 7--13 (2008; Zbl 1189.20062)
Araújo, João; Konieczny, Janusz Automorphisms of endomorphism monoids of relatively free bands. (English) Zbl 1123.20048 Proc. Edinb. Math. Soc., II. Ser. 50, No. 1, 1-21 (2007). Reviewer: Jaak Henno (Tallinn) MSC: 20M07 20M05 20M15 20M20 PDFBibTeX XMLCite \textit{J. Araújo} and \textit{J. Konieczny}, Proc. Edinb. Math. Soc., II. Ser. 50, No. 1, 1--21 (2007; Zbl 1123.20048) Full Text: DOI
Araújo, João; Konieczny, Janusz A method of finding automorphism groups of endomorphism monoids of relational systems. (English) Zbl 1123.20054 Discrete Math. 307, No. 13, 1609-1620 (2007). Reviewer: G. I. Zhitomirskij (Herzliyya) MSC: 20M20 20M15 08A02 20N15 05C25 05C65 PDFBibTeX XMLCite \textit{J. Araújo} and \textit{J. Konieczny}, Discrete Math. 307, No. 13, 1609--1620 (2007; Zbl 1123.20054) Full Text: DOI
Araújo, João; Konieczny, Janusz Dense relations are determined by their endomorphism monoids. (English) Zbl 1069.20059 Semigroup Forum 70, No. 2, 302-306 (2005). MSC: 20M20 20M15 08A02 PDFBibTeX XMLCite \textit{J. Araújo} and \textit{J. Konieczny}, Semigroup Forum 70, No. 2, 302--306 (2005; Zbl 1069.20059) Full Text: DOI Link
Araújo, João; Konieczny, Janusz Semigroups of transformations preserving an equivalence relation and a cross-section. (English) Zbl 1068.20061 Commun. Algebra 32, No. 5, 1917-1935 (2004). MSC: 20M20 PDFBibTeX XMLCite \textit{J. Araújo} and \textit{J. Konieczny}, Commun. Algebra 32, No. 5, 1917--1935 (2004; Zbl 1068.20061) Full Text: DOI
Konieczny, Janusz Semigroups of transformations commuting with injective nilpotents. (English) Zbl 1068.20065 Commun. Algebra 32, No. 4, 1551-1569 (2004). MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny}, Commun. Algebra 32, No. 4, 1551--1569 (2004; Zbl 1068.20065) Full Text: DOI
Araújo, João; Konieczny, Janusz Automorphism groups of centralizers of idempotents. (English) Zbl 1037.20062 J. Algebra 269, No. 1, 227-239 (2003). Reviewer: Huang Wenxue (Scarborough) MSC: 20M20 20M10 20F28 PDFBibTeX XMLCite \textit{J. Araújo} and \textit{J. Konieczny}, J. Algebra 269, No. 1, 227--239 (2003; Zbl 1037.20062) Full Text: DOI
Konieczny, Janusz Regular, inverse, and completely regular centralizers of permutations. (English) Zbl 1027.20046 Math. Bohem. 128, No. 2, 179-186 (2003). MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny}, Math. Bohem. 128, No. 2, 179--186 (2003; Zbl 1027.20046) Full Text: EuDML
Lipscomb, S.; Konieczny, J. The class equation and counting in factorizable monoids. (English) Zbl 1043.20044 Proc. Am. Math. Soc. 131, No. 11, 3345-3351 (2003). Reviewer: Kenneth D. Magill, jun. (Buffalo) MSC: 20M20 PDFBibTeX XMLCite \textit{S. Lipscomb} and \textit{J. Konieczny}, Proc. Am. Math. Soc. 131, No. 11, 3345--3351 (2003; Zbl 1043.20044) Full Text: DOI
Araújo, João; Konieczny, Janusz Molaei’s generalized groups are completely simple semigroups. (English) Zbl 1064.20065 Bul. Inst. Politeh. Iași, Secț. I, Mat. Mec. Teor. Fiz. 48(52), No. 1-2, 1-5 (2002). MSC: 20N02 20M10 PDFBibTeX XMLCite \textit{J. Araújo} and \textit{J. Konieczny}, Bul. Inst. Politeh. Iași, Secț. I, Mat. Mec. Teor. Fiz. 48(52), No. 1--2, 1--5 (2002; Zbl 1064.20065)
Konieczny, Janusz The semigroup generated by regular Boolean matrices. (English) Zbl 1010.20053 Southeast Asian Bull. Math. 25, No. 4, 627-641 (2002). Reviewer: Ki Hang Kim (Montgomery) MSC: 20M20 15B57 PDFBibTeX XMLCite \textit{J. Konieczny}, Southeast Asian Bull. Math. 25, No. 4, 627--641 (2002; Zbl 1010.20053) Full Text: DOI
Konieczny, Janusz Semigroups of transformations commuting with idempotents. (English) Zbl 1005.20046 Algebra Colloq. 9, No. 2, 121-134 (2002). Reviewer: Kenneth D.Magill (Buffalo) MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny}, Algebra Colloq. 9, No. 2, 121--134 (2002; Zbl 1005.20046)
Konieczny, Janusz Second centralizers of partial transformations. (English) Zbl 1003.20053 Czech. Math. J. 51, No. 4, 873-888 (2001). MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny}, Czech. Math. J. 51, No. 4, 873--888 (2001; Zbl 1003.20053) Full Text: DOI EuDML
Konieczny, J.; Lipscomb, S. Path notation for partial transformations. (English) Zbl 0982.20054 Kublanovsky, S. (ed.) et al., Semigroups with applications, including semigroup rings. International conference in honour of E. S. Lyapin, St.-Petersburg, Russia, June 19-30, 1995. St.-Petersburg: Severny Ochag, 95-101 (1999). Reviewer: Kenneth D.Magill (Buffalo) MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny} and \textit{S. Lipscomb}, in: Semigroups with applications, including semigroup rings. International conference in honour of E. S. Lyapin, St. -Petersburg, Russia, June 19--30, 1995. St.-Petersburg: Severny Ochag. 95--101 (1999; Zbl 0982.20054)
Konieczny, Janusz Green’s relations and regularity in centralizers of permutations. (English) Zbl 0924.20049 Glasg. Math. J. 41, No. 1, 45-57 (1999). Reviewer: P.M.Higgins (Colchester) MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny}, Glasg. Math. J. 41, No. 1, 45--57 (1999; Zbl 0924.20049) Full Text: DOI
Konieczny, J.; Lipscomb, S. Centralizers in the semigroup of partial transformations. (English) Zbl 0917.20051 Math. Jap. 48, No. 3, 367-376 (1998). Reviewer: P.M.Higgins (Colchester) MSC: 20M20 PDFBibTeX XMLCite \textit{J. Konieczny} and \textit{S. Lipscomb}, Math. Japon. 48, No. 3, 367--376 (1998; Zbl 0917.20051)
Lipscomb, S.; Konieczny, J. Centralizers of permutations in the partial transformation semigroup. (English) Zbl 0856.20044 PU.M.A., Pure Math. Appl. 6, No. 4, 349-354 (1995). Reviewer: K.D.Magill (Buffalo) MSC: 20M20 20B35 PDFBibTeX XMLCite \textit{S. Lipscomb} and \textit{J. Konieczny}, PU.M.A., Pure Math. Appl. 6, No. 4, 349--354 (1995; Zbl 0856.20044)
Konieczny, Janusz Reduced idempotents in the semigroup of Boolean matrices. (English) Zbl 0849.20046 J. Symb. Comput. 20, No. 4, 471-482 (1995). Reviewer: K.H.Kim (Montgomery) MSC: 20M20 15B57 PDFBibTeX XMLCite \textit{J. Konieczny}, J. Symb. Comput. 20, No. 4, 471--482 (1995; Zbl 0849.20046) Full Text: DOI
Lipscomb, S.; Konieczny, J. Classification of \(S_ n\)-normal semigroups. (English) Zbl 0828.20064 Semigroup Forum 51, No. 1, 73-86 (1995). Reviewer: K.D.Magill (Buffalo) MSC: 20M20 20B35 PDFBibTeX XMLCite \textit{S. Lipscomb} and \textit{J. Konieczny}, Semigroup Forum 51, No. 1, 73--86 (1995; Zbl 0828.20064) Full Text: DOI EuDML
Konieczny, Janusz Green’s equivalences in finite semigroups of binary relations. (English) Zbl 0805.20059 Semigroup Forum 48, No. 2, 235-252 (1994). Reviewer: K.D.Magill (Buffalo) MSC: 20M20 20M15 PDFBibTeX XMLCite \textit{J. Konieczny}, Semigroup Forum 48, No. 2, 235--252 (1994; Zbl 0805.20059) Full Text: DOI EuDML
Konieczny, Janusz Remarks on the structure of the multiplicative monoid of integers modulo \(m\). (English) Zbl 0769.20026 Semigroup Forum 46, No. 2, 266-269 (1993). Reviewer: Št.Porubský (Bratislava) MSC: 20M14 11A05 20M25 16U60 16S36 PDFBibTeX XMLCite \textit{J. Konieczny}, Semigroup Forum 46, No. 2, 266--269 (1993; Zbl 0769.20026) Full Text: DOI EuDML
Konieczny, Janusz On cardinalities of row spaces of Boolean matrices. (English) Zbl 0747.20033 Semigroup Forum 44, No. 3, 393-402 (1992). Reviewer: K.H.Kim (Montgomery) MSC: 20M20 54A10 05B20 54A25 54H15 15A30 PDFBibTeX XMLCite \textit{J. Konieczny}, Semigroup Forum 44, No. 3, 393--402 (1992; Zbl 0747.20033) Full Text: DOI EuDML