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Showing 1 to 13 of 13 for “"central extensions"”.
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Central extensions of divisible groups
This thesis contributes to the classification of central extensions of divisible groups with finite abelian quotient, so called ``d-ab extensions.'' We give a matrix classification of equivalence classes of d-ab extensions and explicitly provide a family of group presentations. We provide a …
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Genus Fields and Central Extensions of Number Fields
… quadratic then we determine all cyclic l-extensions for which l (VBAR) h(,L).
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Lifting bundle gerbes and central extensions of gauge groups
The loop group Map(S¹,G) has a central extension by the circle called the Kac-Moody group. We use the techniques introduced in [29] to generalise this construction to higher mapping groups such as Map(∑,G) and construct the central extension ...
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A CATEGORICAL-ALGEBRAIC EXPLORATION OF MODELS FOR MANY-VALUED LOGIC
… theory and characterizing the corresponding central extensions. These central extensions are themselves reflective into the category of surjective MV-algebra morphisms, and the corresponding adjunction is admissible, too. Thanks to this observation, we characterize higher central extensions, …
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The recategorization of "chaos": a case study of language change and theory change
… This model describes concepts in terms of (1) a central cluster which acts as a prototypical example, and (2) various non-central extensions from that center. I argue that in an emerging discipline, non-central extensions are made depending on the interests of the community. As Andrew Pickering …
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Lie Algebras of Differential Operators and D-modules
… surfaces, along with their outer derivations and central extensions. We show that the corresponding algebras of meromorphic differential operators and pseudodifferential symbols have many invariant traces and central extensions, given by the logarithms of meromorphic vector fields. We describe …
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On Projective Characters of Rotation Sub- Group
… $. This is done by constructing non-trivial central extensions of W ( $) via the double coverings of the rotation groups SO(£). This adaptation gives a unified way of obtaining the basic projective representations of W+( $) from those of W($), determined in [9] . In particular, formulae …
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On Projective Characters of Rotation Sub- Group
… $. This is done by constructing non-trivial central extensions of W ( $) via the double coverings of the rotation groups SO(£). This adaptation gives a unified way of obtaining the basic projective representations of W+( $) from those of W($), determined in [9] . In particular, formulae …
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Three viewpoints on semi-abelian homology
… of Birkhoff subcategory to generate a class of central extensions, which play a big role not only in the definition via Hopf formulae but also in our third viewpoint. This final and new viewpoint we consider is homology via satellites or pointwise Kan extensions. This makes the universal …
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Torsors over Simplicial Schemes
… including an exact sequence associated to a central extension of sheaves of groups, as well as a characterization of the second sheaf cohomology group of BG with coefficients in a sheaf of abelian groups A, in terms of central extensions of G by A. It is well-known that, if k is a perfect …
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Graded-commutative nonassociative algebras: higher octonions and Krichever-Novikov superalgebras; their structures, combinatorics and non-trivial cocycles.
… points generalizing the Witt algebra and its central extension called the Virasoro algebra. The K-N Lie (super)algebras for more than two marked points were studied by Schlichenmaier. In particular, he extended the explicit formula of $2$-cocycles due to Krichever and Novikov to multiple-point …
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On a class of extended toroidal Lie algebras coming from untwisted affine Yangians
… \say{toroidal Lie algebras}, i.e. universal central extensions: $$\toroidal$$ of the Lie algebras of the form: $$\g[v^{\pm 1}, t^{\pm 1}] := \g \tensor_{\bbC} \bbC[v^{\pm 1}, t^{\pm 1}]$$ (so-called \say{double-loop algebras}), where $\g$ is a finite-dimensional simple Lie algebra over …
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SYMMETRIC PRESENTATIONS OF NON-ABELIAN SIMPLE GROUPS
… type of the group. We will present how we solve extensions problems while our main focus will lie on extensions that will include the following: semi-direct products, direct products, central extensions and mixed extensions.Lastly, we will discuss Iwasawa's Lemma and how double coset enumeration …