Results 231 to 240 of about 1,871 (258)

Covering groups and projective representations

1992
In order to deduce Theorem 1.18 from the special case established in the last chapter, we will need to exploit a relationship between characters of tori in G and representations of G. This relationship is most natural when it is formulated in terms of certain coverings of the tori related to “ρ-shifts” for G (see for example Theorem 1.37 or Theorem 6.8
Jeffrey Adams, Dan Barbasch, David A. Vogan   +2 more
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Rings Whose Nonsingular Modules Have Projective Covers

Ukrainian Mathematical Journal, 2016
zbMATH Open Web Interface contents unavailable due to conflicting licenses.
Asgari, Sh., Haghany, A.
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Projective Groups and Frattini Covers

1986
The absolute Galois group of a PAC field is projective (Theorem 10.17). This chapter includes a converse (Corollary 20.16): If G is a projective group, then there exists a PAC field K such that G (K) ≅ G. Projective groups also appear as the universal Frattini covers of profinite groups (Proposition 20.33).
Michael D. Fried, Moshe Jarden
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Directed fibrations and covering projections

Publicationes Mathematicae Debrecen, 2009
Summary: In this note a notion of Hurewicz fibration in the category d{\textbf{Top}} of directed spaces in the sense of \textit{M. Grandis} [Cah. Topol. Géom. Différ. Catég. 44, No.~4, 281--316 (2003; Zbl 1059.55009)] is defined. The directed homotopy lifting property is characterized by means of lifting pairs.
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Our Jan/Feb Cover

Ca-A Cancer Journal for Clinicians, 1981
exaly   +10 more sources

Projective Covers and Perfect Rings

1976
A morphism f: A → B of R-modules is said to be minimal provided that ker f is a superfluous submodule of A. For example, for a right ideal I, the canonical map R → R/I is superfluous if and only if I ⊆ rad R 18.3. A module A is a projective cover (proj. cov.) of B provided that A is projective and there exists a minimal epimorphism A → B.
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Lecture 7- Projective Modules and Projective Covers

Defines projective modules via the lifting property (equivalently, exactness of Hom_A(P,−)); notes that free modules and their direct summands are projective and that all modules are projective over semisimple rings. Introduces projective indecomposable modules (PIMs) and shows the number of PIMs equals the number of Brauer simples.
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Gorenstein injective, projective and flat (pre)covers

2014
Summary: We prove that if the ring \(R\) is left noetherian and if the class \(\mathcal {GI}\) of Gorenstein injective modules is closed under filtrations, then \(\mathcal {GI}\) is precovering. We extend this result to the category of complexes. We also prove that when \(R\) is commutative noetherian and such that the character modules of Gorenstein ...
Enochs, Edgar E., Estrada, Sergio, Iacob, Alina   +2 more
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Vertically Projected Cover

2020
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Projective covers of distributive lattices

Algebra Universalis, 1976
Balbes, Raymond, Horn, Alfred
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