Two remarks on the maximal-ideal space of H
Stephen Scheinberg (2021)
Commentationes Mathematicae Universitatis Carolinae
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The topology of the maximal-ideal space of is discussed.
Stephen Scheinberg (2021)
Commentationes Mathematicae Universitatis Carolinae
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The topology of the maximal-ideal space of is discussed.
W. Żelazko (1969)
Colloquium Mathematicae
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Pierre Matet (2013)
Fundamenta Mathematicae
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We discuss the problem of whether there exists a restriction of the noncofinal ideal on that is normal.
Marta Frankowska, Andrzej Nowik (2011)
Colloquium Mathematicae
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We prove that the ideal (a) defined by the density topology is not generated. This answers a question of Z. Grande and E. Strońska.
Mohammed Hemdaoui (2019)
Mathematica Bohemica
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We show that some unital complex commutative LF-algebra of -tempered functions on (M. Hemdaoui, 2017) equipped with its natural convex vector bornology is useful for functional calculus.
Vladimir Fonf, Menachem Kojman (2001)
Fundamenta Mathematicae
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We investigate countably convex subsets of Banach spaces. A subset of a linear space is countably convex if it can be represented as a countable union of convex sets. A known sufficient condition for countable convexity of an arbitrary subset of a separable normed space is that it does not contain a semi-clique [9]. A semi-clique in a set S is a subset P ⊆ S so that for every x ∈ P and open neighborhood u of x there exists a finite set X ⊆ P ∩ u such that conv(X) ⊈ S. For closed sets...
Masato Kurihara (1999)
Journal of the European Mathematical Society
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In this paper, for a totally real number field we show the ideal class group of is trivial. We also study the -component of the ideal class group of the cyclotomic -extension.
F. Azarpanah, O. A. S. Karamzadeh, S. Rahmati (2008)
Colloquium Mathematicae
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Let be the socle of C(X). It is shown that each prime ideal in is essential. For each h ∈ C(X), we prove that every prime ideal (resp. z-ideal) of C(X)/(h) is essential if and only if the set Z(h) of zeros of h contains no isolated points (resp. int Z(h) = ∅). It is proved that , where dim C(X) denotes the Goldie dimension of C(X), and the inequality may be strict. We also give an algebraic characterization of compact spaces with at most a countable number of nonisolated points....
Pamela Gorkin, Raymond Mortini, Daniel Suárez (2001)
Studia Mathematica
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Let f be a function in the Douglas algebra A and let I be a finitely generated ideal in A. We give an estimate for the distance from f to I that allows us to generalize a result obtained by Bourgain for to arbitrary Douglas algebras.
M. Obradović, S. Owa (1986)
Matematički Vesnik
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James C. Lillo (1967)
Annales Polonici Mathematici
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Piotr Zakrzewski (2015)
Commentationes Mathematicae Universitatis Carolinae
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We give a classical proof of the theorem stating that the -ideal of meager sets is the unique -ideal on a Polish group, generated by closed sets which is invariant under translations and ergodic.
Anna Stasica (2003)
Annales Polonici Mathematici
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We obtain, in a simple way, an estimate for the Noether exponent of an ideal I without embedded components (i.e. we estimate the smallest number μ such that ).
Emel Aslankarayiğit Uğurlu, El Mehdi Bouba, Ünsal Tekir, Suat Koç (2023)
Czechoslovak Mathematical Journal
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We introduce weakly strongly quasi-primary (briefly, wsq-primary) ideals in commutative rings. Let be a commutative ring with a nonzero identity and a proper ideal of . The proper ideal is said to be a weakly strongly quasi-primary ideal if whenever for some , then or Many examples and properties of wsq-primary ideals are given. Also, we characterize nonlocal Noetherian von Neumann regular rings, fields, nonlocal rings over which every proper ideal is wsq-primary, and zero...
Dongyang Chen, William B. Johnson, Bentuo Zheng (2014)
Studia Mathematica
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We give a corrected proof of Theorem 2.10 in our paper “Commutators on ” [Studia Math. 206 (2011), 175-190] for the case 1 < q < p < ∞. The case when 1 = q < p < ∞ remains open. As a consequence, the Main Theorem and Corollary 2.17 in that paper are only valid for 1 < p,q < ∞.
Brahim Boudine (2023)
Mathematica Bohemica
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A commutative ring with unity is called a special principal ideal ring (SPIR) if it is a non integral principal ideal ring containing only one nonzero prime ideal, its length is the index of nilpotency of its maximal ideal. In this paper, we show a characterization of irreducible polynomials over a SPIR of length . Then, we give a sufficient condition for a polynomial to be irreducible over a SPIR of any length .
Tomáš G. Roskovec, Filip Soudský (2023)
Kybernetika
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The weak lower semicontinuity of the functional is a classical topic that was studied thoroughly. It was shown that if the function is continuous and convex in the last variable, the functional is sequentially weakly lower semicontinuous on . However, the known proofs use advanced instruments of real and functional analysis. Our aim here is to present a proof understandable even for students familiar only with the elementary measure theory.
Z. Krzeszowiak (1969)
Annales Polonici Mathematici
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H. Fejzić, R. E. Svetic, C. E. Weil (2010)
Fundamenta Mathematicae
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The main result of this paper is that if f is n-convex on a measurable subset E of ℝ, then f is n-2 times differentiable, n-2 times Peano differentiable and the corresponding derivatives are equal, and except on a countable set. Moreover is approximately differentiable with approximate derivative equal to the nth approximate Peano derivative of f almost everywhere.
Stefan Müller, Vladimír Šverák (1999)
Journal of the European Mathematical Society
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We study solutions of first order partial differential relations , where is a Lipschitz map and is a bounded set in matrices, and extend Gromov’s theory of convex integration in two ways. First, we allow for additional constraints on the minors of and second we replace Gromov’s −convex hull by the (functional) rank-one convex hull. The latter can be much larger than the former and this has important consequences for the existence of ‘wild’ solutions to elliptic systems. Our...