 By Mark R. Sepanski

Blending algebra, research, and topology, the research of compact Lie teams is among the most lovely components of arithmetic and a key stepping stone to the idea of common Lie teams. Assuming no earlier wisdom of Lie teams, this e-book covers the constitution and illustration idea of compact Lie teams. incorporated is the development of the Spin teams, Schur Orthogonality, the Peter–Weyl Theorem, the Plancherel Theorem, the Maximal Torus Theorem, the Commutator Theorem, the Weyl Integration and personality formulation, the top Weight category, and the Borel–Weil Theorem. the mandatory Lie algebra concept can also be constructed within the textual content with a streamlined procedure targeting linear Lie groups.

Key Features:

• presents an technique that minimizes complex prerequisites

• Self-contained and systematic exposition requiring no prior publicity to Lie theory

• Advances quick to the Peter–Weyl Theorem and its corresponding Fourier theory

• Streamlined Lie algebra dialogue reduces the differential geometry prerequisite and permits a extra speedy transition to the type and building of representations

• workouts sprinkled throughout

This starting graduate-level textual content, aimed basically at Lie teams classes and comparable themes, assumes familiarity with basic recommendations from crew conception, research, and manifold concept. scholars, examine mathematicians, and physicists attracted to Lie thought will locate this article very useful.

Best symmetry and group books

Mixing algebra, research, and topology, the research of compact Lie teams is likely one of the most pretty components of arithmetic and a key stepping stone to the speculation of normal Lie teams. Assuming no earlier wisdom of Lie teams, this booklet covers the constitution and illustration concept of compact Lie teams.

Extra resources for Compact Lie Groups

Example text

For instance, the action in number (7) on V ∗ is just the special case of the action in number (3) on Hom(V, W ) in which W = C is the trivial representation. Also the actions in (4), (5), and (6) really only make repeated use of number (2). 20). 2 Irreducibility and Schur’s Lemma Now that we have many ways to glue representations together, it makes sense to seek some sort of classiﬁcation. For this to be successful, it is necessary to examine the smallest possible building blocks. 11. Let G be a Lie group and V a ﬁnite-dimensional representation of G.

As an algebra map, extend ± to ± : Tn (C) → End W . 6) shows that ± (z)2 = m −(z,z) so that ± descends to a map ± : Cn (C) → End W . Thus the map : Cn (C) → End W End W given by (v) = ( + (v) , − (v)) is well deﬁned. To see that is an isomorphism, it sufﬁces to verify that is surjective since Cn (C) and End W End W both have dimension 2n . 7). 9. As algebras, Cn+ (C) ∼ = End + W End End W − W n even n odd. Proof. 8, it is clear that the operators in (Cn+ (C)) preserve ± W . Thus restricted to Cn+ (C), may End − W .

N odd: In this case, operators in (Cn (C)) no longer have to preserve ± W . However, restriction of the map + to Cn+ (C) yields a map of Cn+ (C) to End W (alternatively, − could have been used). By construction, this map is known to be surjective. Thus to see that the map is an isomorphism, it again sufﬁces to show that dim End W = dim Cn+ (C). 9) to see that both dimensions are 2n−1 . At long last, the origin of the spin representations can be untangled. 9 for n even and the homomorphism + for n odd and restricts the action to Spinn (R).