Miguel Ferrero
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Інститут прикладної математики і механіки НАН України
2008
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| Цитувати: | Miguel Ferrero / M. Dokuchaev, V. Kirichenko, A. Paques, A. Sant’Ana // Algebra and Discrete Mathematics. — 2008. — Vol. 7, № 4. — С. 90–99. — Бібліогр.: 78 назв. — англ. |
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irk-123456789-1533752019-06-15T01:26:30Z Miguel Ferrero Dokuchaev, M. Kirichenko, V. Paques, A. Sant’Ana, A. 2008 Article Miguel Ferrero / M. Dokuchaev, V. Kirichenko, A. Paques, A. Sant’Ana // Algebra and Discrete Mathematics. — 2008. — Vol. 7, № 4. — С. 90–99. — Бібліогр.: 78 назв. — англ. 1726-3255 http://dspace.nbuv.gov.ua/handle/123456789/153375 en Algebra and Discrete Mathematics Інститут прикладної математики і механіки НАН України |
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Dokuchaev, M. Kirichenko, V. Paques, A. Sant’Ana, A. |
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Dokuchaev, M. Kirichenko, V. Paques, A. Sant’Ana, A. Miguel Ferrero Algebra and Discrete Mathematics |
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Dokuchaev, M. Kirichenko, V. Paques, A. Sant’Ana, A. |
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| title |
Miguel Ferrero |
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Miguel Ferrero |
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Miguel Ferrero |
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Miguel Ferrero |
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Miguel Ferrero |
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miguel ferrero |
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Інститут прикладної математики і механіки НАН України |
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2008 |
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http://dspace.nbuv.gov.ua/handle/123456789/153375 |
| citation_txt |
Miguel Ferrero / M. Dokuchaev, V. Kirichenko, A. Paques, A. Sant’Ana // Algebra and Discrete Mathematics. — 2008. — Vol. 7, № 4. — С. 90–99. — Бібліогр.: 78 назв. — англ. |
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Algebra and Discrete Mathematics |
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AT dokuchaevm miguelferrero AT kirichenkov miguelferrero AT paquesa miguelferrero AT santanaa miguelferrero |
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2025-07-14T04:36:06Z |
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2025-07-14T04:36:06Z |
| _version_ |
1837595641078874112 |
| fulltext |
Algebra and Discrete Mathematics SURVEY ARTICLE
Number 4. (2008). pp. 90 – 99
c© Journal “Algebra and Discrete Mathematics”
Miguel Ferrero
Michael Dokuchaev, Vladimir Kirichenko, Antonio
Paques, Alveri Sant’Ana
Abstract. This is a short survey of Miguel Ferrero’s aca-
demic activity written on the occasion of his 70th birthday.
Miguel Angel Alberto Ferrero, internationally known shortly as Miguel
Ferrero, was born on September, 14, 1938, in Cañada Rosqúin of the
Province of Santa Fé in Argentina. In 1963 he graduated from Univer-
sidad Nacional de Rosario and in 1970 he obtained his PhD Degree at
Universidad de Buenos Aires, defending the PhD Thesis “Teoria de Galois
para Anillos Graduados" (“Galois theory for Graded Rings”) under the
supervision of Professor Orlando Villamayor. He was working at Univer-
sidad Nacional de Rosario from 1959 to 1976, occupying various positions
from Auxiliary Professor to a Titular Professor.
M. Dokuchaev, V. Kirichenko, A. Paques, A. Sant’Ana 91
Miguel Ferrero came to Brazil in 1976 starting his teaching and re-
search activities at the Universidade Estadual de Campinas (Unicamp).
Since 1977 he is a Professor at Universidade Federal do Rio Grande do
Sul (UFRGS), where he was one of the founders of the Graduate Course
in Mathematics.
Miguel Ferrero research interests include such topics as Galois Theory,
the theory of radicals, ring extensions, the structure of prime ideals, dis-
tributivity of rings and modules, polynomial and skew polynomial rings,
(skew) Laurent polynomial rings, partial actions on rings, as well as some
other related subjects.
The intensive algebraic research activity of Miguel Ferrero started
with Galois Theory (see [70] - [77]), one of the most beautiful areas in
Mathematics which keeps him occupied till nowadays. Influenced partly
by the results of his supervisor O. E. Villamayor obtained with D. Zelin-
sky in the sixties, and by the classical paper of S. Chase, D. K. Har-
rison and A. Rosenberg on Galois Theory of commutative rings (1965),
Miguel obtained in a number of articles (some of them in collaboration
with other authors) generalizations and refinements of fundamental re-
sults from both of these references, including his first algebraic paper
[77] published in 1970, the improvement of Galois Theory of commuta-
tive rings given with A. Paques in [27] (1997), as well one of the most
recent steps, the development of Galois Theory based on partial actions
in collaboration with M. Dokuchaev and A. Paques (2007, [4]). Other
significant contributions to Galois Theory include results on outer Galois
Theory (1976, [70]), connectedness of Galois extensions (with K. Kishi-
moto, 1983, [63]), Zp-extensions (with A. Paques and A. Solecki, 1991,
[50]) and dihedral Galois extensions (with A. Paques, 1999, [22]).
Starting from late seventies Miguel Ferrero’s interest broadened inclu-
ding a number of topics of classical ring theory and resulting in remark-
able contributions. Some of the main streams of ring theory, such as
the study of polynomial, skew, Laurent polynomial rings, more general
ring extensions, their prime ideals, radicals and automorphisms, as well
as distributivity in rings and modules and derivations of rings, became
also main streams of Miguel’s research. As examples one can examine
his remarkable contributions in the study of radicals, starting with his
paper with K. Kishimoto and K. Motose [64] published in 1983, and in
the related topic of the investigation of prime ideals in polynomial rings,
including their skew and Laurent versions and more generally, in central-
izing and normalizing extensions.
The latter theme had several developments, including the introduc-
92 Miguel Ferrero
tion of the concept of a (principal) closed ideal in Miguel’s 1990 paper
[53], and its application to the study of prime ideals in polynomial rings
in the same paper, as well as in Ore extensions in two other articles pub-
lished in the same year, one of which with E. Cisneros and M. I. Gonzáles
[51], and another one with J. Matczuk [54]. In fact, Miguel’s 1990 paper
on closed ideals induced a series of articles on the subject in which the
idea was further developed resulting in a powerful method with many
applications. In particular, the technique was successfully used in more
general case of free centered extensions in [48] (1992), which include such
examples as semigroup rings, matrix rings and tensor products. The next
notable step was the passage to non-necessarily free centered extensions
via use of more general closed submodules in centered bimodules with
prime base ring in [39] (1995). Soon afterwards the semi-prime base ring
case was also handled in [29] (1996).
Many results and applications were obtained as a consequence of the
method. Thus in the above mentioned 1995 paper valuable applications
were given to non-singular modules, strongly prime rings and strongly
closed submodules, as well as to the torsion-free rank and the Goldie
dimension of a submodule. In a paper with E. Puczilowski [31] (1996)
important applications were obtained to radicals of centered extensions,
including the prime, strongly prime, locally nilpotent, nil, singular Jacob-
son and Brown-McCoy radicals, as well as to the study of prime ideals
in tensor products. Further results and developments were obtained in
[33](1996, with R. Wisbauer), [24] (1998), [18] (2001) and more recently
in [10] (2004, with R. R. Steffenon).
Beside the general facts on closed and prime ideals, in the case of
polynomial rings more specific valuable information was obtained in [36]
and [28]. The results in the latter paper are especially elegant: It is
a basic fact that an ideal P of the polynomial ring K[x] over a field
K is prime exactly when P = (f) for some irreducible polynomial f .
Miguel gave a generalization of this for the polynomial ring R[x] over an
arbitrary ring R with identity: it was shown that there exists a one-to-
one correspondence between the prime ideals in R[x] and the pairs (Q, f),
where Q = P∩R, a prime ideal in R, and f is a “ΓQ-completely irreducible
polynomial” in R[x]. This fact was used then to describe the prime ideals
in the polynomial ring R[x1, . . . xn] over arbitrary R. In particular, any
prime ideal P of R[x1, . . . xn] is determined by its intersection with R
plus n polynomials.
One of the famous problems in ring theory is the Köthe’s Conjecture.
It is well-known that if I and J are two-sided nil ideals in a non-necessarily
M. Dokuchaev, V. Kirichenko, A. Paques, A. Sant’Ana 93
unital ring R then I +J is nil. It is also true that if I and J are nilpotent
left ideals then so too is I+J. However it is far from being known whether
I + J is nil, provided that I and J are left nil ideals. The Köthe’s
Conjecture says that this is the case, and it has a number of equivalent
formulations. Some of them were given by Miguel Ferrero and Edmund
Puczylowski in [55] and they are interesting enough to being recalled
here. Assume that R = R1 + R2, where R1, R2 are subrings. Then the
following assertions are equivalent to the Köthe’s Conjecture: (1) R is nil,
provided that R1 is nilpotent and R2 is nil. (2) R is nil, provided that R1
is right (or left) T -nilpotent and R2 is nil. These facts were obtained as
consequences of more general results concerning radicals. Assume that R1
is right T -nilpotent. Then for many radicals S, including the Jacobson,
locally nilpotent, the prime, the right strongly prime and the generalized
nil radicals, it was proved that if R2 is an S-radical ring then R is also
an S-radical ring. The corresponding statement for the nil radical is
equivalent to Köthe’s Conjecture.
Another article related to Köthe’s Conjecture was done in collabora-
tion with R. Wisbauer [12] and deals in particular with radicals of poly-
nomial rings. According to a result by Jan Krempa (1972), the Köthe’s
Conjecture is equivalent to the following statement: If R is a nil ring
then R[x] is a Jacobson radical ring. E. Puczylowski and A. Smoktunow-
icz (1998) proved that if R is nil then R[x] is a Brown-McCoy radical
ring. Recall that the Brown-McCoy radical contains the Jacobson rad-
ical. J. Krempa determined the Brown-McCoy radical of R[x] and M.
Ferrero and R. Wisbauer went on to polynomial rings with various in-
determinates. More precisely they study the Brown-McCoy radical and
the unitary strongly prime (u-strongly prime, for short) radical. The u-
strongly prime radical S(R) of a ring R is defined as the intersection of
all prime ideals P of R such that R/P is a u-strongly prime ring, i. e.
the central closure of R/P is a simple ring with 1. It is proved that if R
is any ring and X is a finite or infinite set of either commuting or non-
commuting indeterminates, then S(R[X]) = S(R)[X]. It is also shown
that if R is an arbitrary ring and X is an infinite set of either commut-
ing or non-commuting indeterminates, then the Brown-McCoy radical of
R[X] is S(R)[X]. The latter conclusion still holds with finite X provided
that R is a PI-ring.
Between 1993 and 2005 Miguel, with several other collaborators, pro-
duced a series of articles dedicated to another topic of systematic interest,
namely that of chain rings, distributive rings, the more general so-called
rings with comparability, as well as Bezout rings: [45], [44], [42], [38],
[26], [23], [17], [11], [8] (see also [7]). The main attention was paid to
94 Miguel Ferrero
right distributive rings and right Bezout rings wich contain a completely
prime ideal in their Jacobson radical. In particular, a sort of comparabil-
ity was used, envolving elements, which turned out to be rather efficient
in this study, permitting to describe the structure of ideals of these rings,
as well as to obtain known results with more direct and simple proofs.
As an effect, the structure of such rings below the Jacobson radical was
completely determined. On the other hand, very little is known about
their structure above the Jacobson radical. Information about these rings
above the Jacobson radical corresponds to information about distributive
(Bezout) J-semisimple domains, which are not well undestrood. In this
direction, in [26] the authors ask the following question: does there exist
a J-semisimple right distributive domain which is not left distributive?
Miguel’s research production is not limited to the articles cited above
and includes other relevant papers on the above mentioned topics, as
well as on derivations and higher derivations, some interesting isolated
publications, and the intensive recent production on partial actions, a
new attractive topic in algebra which comes from the theory of operator
algebras, and which involves several of his former and present students,
as well as other collaborators. The list of publications by Miguel Ferrero
is given in the references below.
Miguel Ferrero supervised 10 Master Degree students and 10 PhD
students which are working nowadays at several universities in the south
of Brazil. He published 78 scientific articles, was an editor of Communi-
cations in Algebra since 1992 till 2006, and at the moment he is member
of editorial boards of The East-West Journal of Mathematics (since 1998)
and Journal of Algebra and its Applications (since 2001). Miguel Ferrero
was honored by the award “FAPERGS - Pesquisadores Destaque 2001",
in area of Informatics, Mathematics and Statistics in recognition of his
scientific work.
In 1998, Miguel Ferrero organized the XV Escola de Álgebra (XV
Brazilian School of Algebra) which was held in Canela (Brasil), from 26
of July till 1 of August, and edited its proceedings. This conference had
approximately 200 participant, many of them from abroad.
References
[1] Ferrero, Miguel; Lazzarin, João, Partial actions and partial skew group rings. J.
Algebra 319 (2008), no. 12, 5247–5264.
[2] Bagio, Dirceu; Cortes, Wagner; Ferrero, Miguel; Paques, Antonio, Actions of
inverse semigroups on algebras. Comm. Algebra 35 (2007), no. 12, 3865–3874.
M. Dokuchaev, V. Kirichenko, A. Paques, A. Sant’Ana 95
[3] Cortes, Wagner; Ferrero, Miguel, Partial skew polynomial rings: prime and max-
imal ideals. Comm. Algebra 35 (2007), no. 4, 1183–1199.
[4] Dokuchaev, Michael; Ferrero, Miguel; Paques, Antonio, Partial actions and Galois
theory. J. Pure Appl. Algebra 208 (2007), no. 1, 77–87.
[5] Ferrero, Miguel; Rodrigues, Virginia, On prime and semiprime modules and co-
modules. J. Algebra Appl. 5 (2006), no. 5, 681–694.
[6] Ferrero, Miguel, Partial actions of groups on semiprime rings. Groups, rings and
group rings, 155–162, Lect. Notes Pure Appl. Math., 248, Chapman & Hall/CRC,
Boca Raton, FL, 2006.
[7] Ferrero, Miguel; Mazurek, Ryszard; Sant’Ana, Alveri, On right chain semigroups.
J. Algebra 292 (2005), no. 2, 574–584.
[8] Ferrero, Miguel; Mazurek, Ryszard, On the structure of distributive and Bezout
rings with waists. Forum Math. 17 (2005), no. 2, 191–198.
[9] Cortes, Wagner; Ferrero, Miguel, Principal ideals in Ore extensions. Math. J.
Okayama Univ. 46 (2004), 77–84.
[10] Ferrero, Miguel; Steffenon, Rogério Ricardo, Normalizing extensions of semiprime
rings. Beiträge Algebra Geom. 45 (2004), no. 1, 117–131.
[11] Ferrero, Miguel; Sant’Ana, Alveri, On distributive modules and rings. Results
Math. 44 (2003), no. 1-2, 74–85.
[12] Ferrero, Miguel; Wisbauer, Robert, Unitary strongly prime rings and related
radicals. J. Pure Appl. Algebra 181 (2003), no. 2-3, 209–226.
[13] Ferrero, Miguel, Unitary strongly prime rings and ideals. Proceedings of the 35th
Symposium on Ring Theory and Representation Theory (Okayama, 2002), 101–
111, Symp. Ring Theory Represent Theory Organ. Comm., Okayama, 2003.
[14] Ferrero, Miguel; Haetinger, Claus, Higher derivations and a theorem by Herstein.
Quaest. Math. 25 (2002), no. 2, 249–257.
[15] Ferrero, Miguel; Haetinger, Claus, Higher derivations of semiprime rings. Comm.
Algebra 30 (2002), no. 5, 2321–2333.
[16] Ferrero, Miguel, An introduction to Köthe’s conjecture and polynomial rings.
IX Algebra Meeting USP/UNICAMP/UNESP (Portuguese) (Sгo Pedro, 2001).
Resenhas 5 (2001), no. 2, 139–148.
[17] Ferrero, Miguel; Sant’Ana, Alveri, Modules with comparability. Publ. Math. De-
brecen 59 (2001), no. 1-2, 221–234.
[18] Ferrero, Miguel, Closed submodules of normalizing bimodules over semiprime
rings. Comm. Algebra 29 (2001), no. 4, 1513–1550.
[19] Ferrero, Miguel; Matczuk, Jerzy, Strongly primeness and singular ideals of skew
polynomial rings. Math. J. Okayama Univ. 42 (2000), 11–17 (2002).
[20] Ferrero, Miguel; Matczuk, Jerzy, Skew polynomial rings with wide family of prime
ideals. Interactions between ring theory and representations of algebras (Murcia),
169–178, Lecture Notes in Pure and Appl. Math., 210, Dekker, New York, 2000.
96 Miguel Ferrero
[21] XV Escola de Álgebra. [15th School of Algebra] Proceedings of the school held
in Canela, July 26–31, 1998. Edited by M. Ferrero and A. M. S. Doering. Mat.
Contemp. 16 (1999). Sociedade Brasileira de Matemática, Rio de Janeiro, 1999.
pp. i–viii and 1–313.
[22] Ferrero, Miguel; Paques, Antonio, On dihedral extensions of commutative rings.
Int. J. Math. Game Theory Algebra 9 (1999), no. 1, 15–34.
[23] Ferrero, Miguel; Sant’Ana, Alveri, Rings with comparability. Canad. Math. Bull.
42 (1999), no. 2, 174–183.
[24] Ferrero, Miguel, Some new results on closed submodules and ideals. East-West J.
Math. 1 (1998), no. 1, 95–107.
[25] Ferrero, Miguel; Puczylowski, Edmund R., The singular ideal and radicals. J.
Austral. Math. Soc. Ser. A 64 (1998), no. 2, 195–209.
[26] Ferrero, Miguel; Paques, Antonio, A note on the structure of distributive rings.
Arch. Math. (Basel) 70 (1998), no. 2, 111–117.
[27] Ferrero, Miguel; Paques, Antonio, Galois theory of commutative rings revisited.
Beiträge Algebra Geom. 38 (1997), no. 2, 399–410.
[28] Ferrero, Miguel, Prime ideals in polynomial rings in several indeterminates. Proc.
Amer. Math. Soc. 125 (1997), no. 1, 67–74.
[29] Ferrero, Miguel, Closed submodules of centred bimodules over semiprime rings,
and applications to ring extensions. Nova J. Math. Game Theory Algebra 5 (1996),
no. 4, 309–345.
[30] Ferrero, Miguel, Prime ideals and semisimplicity of free centred extensions. Rings
and radicals (Shijiazhuang, 1994), 28–33, Pitman Res. Notes Math. Ser., 346,
Longman, Harlow, 1996.
[31] Ferrero, Miguel; Puczylowski, Edmund R., Prime ideals and radicals of centered
extensions and tensor products. Israel J. Math. 94 (1996), 381–401.
[32] Ferrero, M.; Puczylowski, E. R.; Sidki, S., On the representation of an idempotent
as a sum of nilpotent elements. Canad. Math. Bull. 39 (1996), no. 2, 178–185.
[33] Ferrero, Miguel; Wisbauer, Robert, Closure operations in module categories. Al-
gebra Colloq. 3 (1996), no. 2, 169–182.
[34] Ferrero, Miguel; Giambruno, Antonio; Milies, César Polcino, A note on deriva-
tions of group rings. Canad. Math. Bull. 38 (1995), no. 4, 434–437.
[35] Ferrero, Miguel, Closed submodules of centred bimodules over prime rings, and
applications. Resenhas 2 (1995), no. 1, 139–156.
[36] Ferrero, Miguel, Prime and maximal ideals in polynomial rings. Glasgow Math.
J. 37 (1995), no. 3, 351–362.
[37] Ferrero, Miguel, Radicals and the singular ideal. Volume in homage to Dr. Rodolfo
A. Ricabarra (Spanish), 75–82, Vol. Homenaje, 1, Univ. Nac. del Sur, Bahнa
Blanca, 1995.
[38] Ferrero, Miguel; Törner, Günter, On waists of right distributive rings. Forum
Math. 7 (1995), no. 4, 419–433.
M. Dokuchaev, V. Kirichenko, A. Paques, A. Sant’Ana 97
[39] Ferrero, Miguel, Centred bimodules over prime rings: closed submodules and
applications to ring extensions. J. Algebra 172 (1995), no. 2, 470–505.
[40] Ferrero, Miguel, Semisimplicity of free centred extensions. Canad. Math. Bull. 38
(1995), no. 1, 55–58.
[41] Ferrero, Miguel; Paques, Antonio, On R-automorphisms of R[X]. Math. J.
Okayama Univ. 36 (1994), 63–75 (1995).
[42] Ferrero, Miguel, Chain rings and distributive rings. XII School of Algebra, Part
I (Portuguese) (Diamantina, 1992). Mat. Contemp. 6 (1994), 19–24.
[43] Cisneros, Eduardo; Ferrero, Miguel; González, Maŕıa Inés, Ore extensions and
Jacobson rings. Comm. Algebra 21 (1993), no. 11, 3963–3976.
[44] Ferrero, Miguel; Törner, Günter, On the ideal structure of right distributive rings.
Comm. Algebra 21 (1993), no. 8, 2697–2713.
[45] Ferrero, Miguel; Törner, Günter, Rings with annihilator chain conditions and
right distributive rings. Proc. Amer. Math. Soc. 119 (1993), no. 2, 401–405.
[46] Ferrero, Miguel; Paques, Antonio; Solecki, Andrzej, On cyclic quartic extensions
with normal basis. Bull. Sci. Math. 116 (1992), no. 4, 487–500.
[47] Ferrero, Miguel; Lequain, Yves; Nowicki, Andrzej, A note on locally nilpotent
derivations. J. Pure Appl. Algebra 79 (1992), no. 1, 45–50.
[48] Ferrero, Miguel, Closed and prime ideals in free centred extensions. J. Algebra
148 (1992), no. 1, 1–16.
[49] Ferrero, Miguel; Nowicki, Andrzej, Locally integral derivations and endomor-
phisms. Math. J. Okayama Univ. 33 (1991), 103–114.
[50] Ferrero, Miguel; Paques, Antonio; Solecki, Andrzej, On Zp-extensions of commu-
tative rings. J. Pure Appl. Algebra 72 (1991), no. 1, 5–22.
[51] Cisneros, Eduardo; Ferrero, Miguel; González, Maŕıa Inés, Prime ideals of skew
polynomial rings and skew Laurent polynomial rings. Math. J. Okayama Univ.
32 (1990), 61–72.
[52] Ferrero, Miguel; Jespers, Eric; Puczylowski, Edmund R., Prime ideals of graded
rings and related matters. Comm. Algebra 18 (1990), no. 11, 3819–3834.
[53] Ferrero, Miguel, Prime and principal closed ideals in polynomial rings. J. Algebra
134 (1990), no. 1, 45–59.
[54] Ferrero, Miguel; Matczuk, J., Prime ideals in skew polynomial rings of derivation
type. Comm. Algebra 18 (1990), no. 3, 689–710.
[55] Ferrero, Miguel; Puczylowski, Edmund R., On rings which are sums of two sub-
rings. Arch. Math. (Basel) 53 (1989), no. 1, 4–10.
[56] Ferrero, Miguel, The strongly prime radical of an Ore extension. Comm. Algebra
17 (1989), no. 2, 351–376.
[57] Ferrero, Miguel; Parmenter, Michael M., A note on Jacobson rings and polynomial
rings. Proc. Amer. Math. Soc. 105 (1989), no. 2, 281–286.
[58] Ferrero, Miguel, Radicals of skew polynomial rings and skew Laurent polynomial
rings. Math. J. Okayama Univ. 29 (1987), 119–126 (1988).
98 Miguel Ferrero
[59] Ferrero, Miguel, Differential rings and Ore extensions: Brown-McCoy rings. Bol.
Soc. Brasil. Mat. 17 (1986), no. 1, 75–90.
[60] Ferrero, Miguel, A note on liberal extensions with automorphisms. Rev. Union
Mat. Arg. 32 (1986), 196–205.
[61] Ferrero, Miguel; Kishimoto, Kazuo, On differential rings and skew polynomials.
Comm. Algebra 13 (1985), no. 2, 285–304.
[62] Ferrero, Miguel, (ρ, D)-separable extensions. Math. Japon. 29 (1984), no. 5, 707–
719.
[63] Ferrero, Miguel; Kishimoto, Kazuo, On connectedness of p-Galois extensions of
rings. Math. J. Okayama Univ. 25 (1983), no. 2, 103–121.
[64] Ferrero, Miguel; Kishimoto, Kazuo; Motose, Kaoru, On radicals of skew polyno-
mial rings of derivation type. J. London Math. Soc. (2) 28 (1983), no. 1, 8–16.
[65] Baumvol, Gelsa; Ferrero, Miguel, On isomorphisms between skew polynomial
rings. Math. Notae 29 (1981/82), 9–18.
[66] Ferrero, Miguel; Kishimoto, Kazuo, A classification of abelian extensions of rings.
Math. J. Okayama Univ. 23 (1981), no. 2, 117–124.
[67] Ferrero, Miguel, On generalized convolution rings of arithmetic functions. Tsukuba
J. Math. 4 (1980), no. 2, 161–176.
[68] Ferrero, Miguel; Kishimoto, Kazuo, On automorphisms of skew polynomial rings
of derivation type. Math. J. Okayama Univ. 22 (1980), no. 1, 21–26.
[69] Ferrero, Miguel; Micali, Artibano, Sur les n-applications. (French) Colloque sur
les Formes Quadratiques, 2 (Montpellier, 1977). Bull. Soc. Math. France Mйm.
No. 59 (1979), 33–53.
[70] Ferrero, Miguel, Galois theory by reduction to the center. Math. Notae 25 (1976),
19–27.
[71] Bruno, S.; Ferrero, Miguel, On the categories of affine and baricentral spaces.
Math. Notae 25 (1976), 11–18.
[72] Ferrero, Miguel, Correction to: “Galois theory and Clifford algebras” (Math. No-
tae 23 (1972/73), 99–101). Math. Notae 24 (1974/75), 97.
[73] Ferrero, Miguel, On isomorphisms of weakly Galois extensions. Math. J. Okayama
Univ. 17 (1974), 39–47.
[74] Ferrero, Miguel, A note on Galois theory. Math. J. Okayama Univ. 16 (1973),
11–16.
[75] Ferrero, Miguel, Galois theory and Clifford algebras. Math. Notae 23 (1972/73),
99–101.
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M. Dokuchaev, V. Kirichenko, A. Paques, A. Sant’Ana 99
Contact information
M. Dokuchaev Instituto de Matemática e Estat́ıstica, Uni-
versidade de São Paulo, 05508-090 São
Paulo, SP, Brasil
V. Kirichenko Faculty of Mechanics and Mathematics,
Kyiv National Taras Shevchenko Univ.,
Volodymyrska str., 64, 01033 Kyiv, Ukraine
A. Paques Instituto de Matemática
Universidade Federal do Rio Grande do Sul
91509-900, Porto Alegre, RS, Brazil
A. Sant’Ana Instituto de Matemática
Universidade Federal do Rio Grande do Sul
91509-900, Porto Alegre, RS, Brazil
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