scholarly journals The orbit method for locally nilpotent infinite-dimensional Lie algebras

2021 ◽  
Author(s):  
Mikhail Ignatyev ◽  
Alexey Petukhov
Keyword(s):  
Lie Algebras ◽  
Orbit Method ◽  
Infinite Dimensional ◽  
Locally Nilpotent

scholarly journals Corwin–Greenleaf multiplicity function for compact extensions of ℝn

2015 ◽  
Vol 26 (10) ◽  
pp. 1550084 ◽  
Author(s):  
Majdi Ben Halima ◽  
Anis Messaoud
Keyword(s):  
Lie Algebras ◽  
Unitary Representations ◽  
Multiplicity Function ◽  
Natural Projection ◽  
Coadjoint Orbits ◽  
Sufficient Condition ◽  
Orbit Method ◽  
Infinite Dimensional ◽  
Connected Subgroup ◽  
The Relationship

Let G = K ⋉ ℝn, where K is a compact connected subgroup of O(n) acting on ℝn by rotations. Let 𝔤 ⊃ 𝔨 be the respective Lie algebras of G and K, and pr : 𝔤* → 𝔨* the natural projection. For admissible coadjoint orbits [Formula: see text] and [Formula: see text], we denote by [Formula: see text] the number of K-orbits in [Formula: see text], which is called the Corwin–Greenleaf multiplicity function. Let π ∈ Ĝ and [Formula: see text] be the unitary representations corresponding, respectively, to [Formula: see text] and [Formula: see text] by the orbit method. In this paper, we investigate the relationship between [Formula: see text] and the multiplicity m(π, τ) of τ in the restriction of π to K. If π is infinite-dimensional and the associated little group is connected, we show that [Formula: see text] if and only if m(π, τ) ≠ 0. Furthermore, for K = SO(n), n ≥ 3, we give a sufficient condition on the representations π and τ in order that [Formula: see text].

scholarly journals On complete reducibility for infinite-dimensional Lie algebras

2011 ◽  
Vol 226 (2) ◽  
pp. 1911-1972 ◽  
Author(s):  
Maria Gorelik ◽  
Victor Kac
Keyword(s):  
Lie Algebras ◽  
Infinite Dimensional ◽  
Complete Reducibility

A note on the algebra of Poisson brackets

1984 ◽  
Vol 96 (1) ◽  
pp. 45-60 ◽  
Author(s):  
C. J. Atkin
Keyword(s):  
Poisson Bracket ◽  
Lie Algebra ◽  
Lie Algebras ◽  
Symplectic Manifold ◽  
Vector Fields ◽  
Poisson Brackets ◽  
Infinite Dimensional

In a long sequence of notes in the Comptes Rendus and elsewhere, and in the papers [1], [2], [3], [6], [7], Lichnerowicz and his collaborators have studied the ‘classical infinite-dimensional Lie algebras’, their derivations, automorphisms, co-homology, and other properties. The most familiar of these algebras is the Lie algebra of C∞ vector fields on a C∞ manifold. Another is the Lie algebra of ‘Poisson brackets’, that is, of C∞ functions on a C∞ symplectic manifold, with the Poisson bracket as composition; some questions concerning this algebra are of considerable interest in the theory of quantization – see, for instance, [2] and [3].

On Weight Systems Derived from Heisenberg Lie Algebras

2003 ◽  
Vol 12 (05) ◽  
pp. 589-604
Author(s):  
Hideaki Nishihara
Keyword(s):  
Lie Algebra ◽  
Lie Algebras ◽  
Weight System ◽  
Infinite Dimensional ◽  
Conway Polynomial ◽  
Knot Invariant ◽  
Polynomial Representations ◽  
Solvable Lie Algebras

Weight systems are constructed with solvable Lie algebras and their infinite dimensional representations. With a Heisenberg Lie algebra and its polynomial representations, the derived weight system vanishes on Jacobi diagrams with positive loop-degree on a circle, and it is proved that the derived knot invariant is the inverse of the Alexander-Conway polynomial.

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