Quantum enveloping algebra

From HandWiki

In mathematics, a quantum or quantized enveloping algebra is a q-analog of a universal enveloping algebra.[1] Given a Lie algebra [math]\displaystyle{ \mathfrak{g} }[/math], the quantum enveloping algebra is typically denoted as [math]\displaystyle{ U_q(\mathfrak{g}) }[/math]. Among the applications, studying the [math]\displaystyle{ q \to 0 }[/math] limit led to the discovery of crystal bases.

The case of [math]\displaystyle{ \mathfrak{sl}_2 }[/math]

Michio Jimbo considered the algebras with three generators related by the three commutators

[math]\displaystyle{ [h,e] = 2e,\ [h,f] = -2f,\ [e,f] = \sinh(\eta h)/\sinh \eta. }[/math]

When [math]\displaystyle{ \eta \to 0 }[/math], these reduce to the commutators that define the special linear Lie algebra [math]\displaystyle{ \mathfrak{sl}_2 }[/math]. In contrast, for nonzero [math]\displaystyle{ \eta }[/math], the algebra defined by these relations is not a Lie algebra but instead an associative algebra that can be regarded as a deformation of the universal enveloping algebra of [math]\displaystyle{ \mathfrak{sl}_2 }[/math].[2]

References

  1. Kassel, Christian (1995), Quantum groups, Graduate Texts in Mathematics, 155, Berlin, New York: Springer-Verlag, ISBN 978-0-387-94370-1, https://archive.org/details/quantumgroups0000kass 
  2. Jimbo, Michio (1985), "A [math]\displaystyle{ q }[/math]-difference analogue of [math]\displaystyle{ U(\mathfrak{g}) }[/math] and the Yang–Baxter equation", Letters in Mathematical Physics 10 (1): 63–69, doi:10.1007/BF00704588, Bibcode1985LMaPh..10...63J 
  • Drinfel'd, V. G. (1987), "Quantum Groups", Proceedings of the International Congress of Mathematicians 986 (American Mathematical Society) 1: 798–820 

External links