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| | [No title] (Site not responding. Last check: 2007-10-13) |
 | | D(g) is unitary forall g in G. Properties: I will use ` to denote "dagger"= transpose and conjugate * D(g)` D(g) = e * D1(g) not unitary, and D2(g) unitary with D1(g)=M^D2(g)M can occur. |
 | | Theorem: given N dim representation, D, of a finite group G of order h, D is equivalent to a unitary representation of G. Proof: Let X = Sum(i=1,h,D(g)`D(g)). |
 | | forall a in G: D`(a)XD(a)=Sum(i=1,h,D`(a)D`(gi)D(gi)D(a))=Sum(i=1,h,D`(gia)D(gia))=X D`S^2D=S^2 let D~=SDS^ => D~`=(SDS^)`=S^`D`S`=S^D`S D~`D~=I => D~ is unitary and D~ is equivalent to D. Theorem: any non-compact group has no finite dime unitary irreps. |
| www.cs.cmu.edu /~jcl/classnotes/math/group_theory/unitary.txt (127 words) |
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