Triangular Products of Group Representations and Their Applications (Progress in Mathematics)

Vovsi, S.M.

ISBN 10: 0817630627 / ISBN 13: 9780817630621

Edité par Birkhäuser, 1981

A propos de cet article

N° de réf. du vendeur mon0000401645

Détails bibliographiques

• Titre: Triangular Products of Group Representations and Their Applications (Progress in Mathematics)
• Éditeur: Birkhäuser
• Date de parution: 1981
• Langue: anglais
• ISBN à 10 chiffres: 0817630627
• ISBN à 13 chiffres: 9780817630621
• Reliure: Hardcover
• État de l'article: Fine

A propos de ce titre

Synopsis

The construction considered in these notes is based on a very simple idea. Let (A, G ) and (B, G ) be two group representations, for definiteness faithful and finite- 1 2 dimensional, over an arbitrary field. We shall say that a faithful representation (V, G) is an extension of (A, G ) by (B, G ) if there is a G-submodule W of V such that 1 2 the naturally arising representations (W, G) and (V/W, G) are isomorphic, modulo their kernels, to (A, G ) and (B, G ) respectively. 1 2 Question. Among all the extensions of (A, G ) by (B, G ), does there exist 1 2 such a "universal" extension which contains an isomorphic copy of any other one? The answer is in the affirmative. Really, let dim A = m and dim B = n, then the groups G and G may be considered as matrix groups of degrees m and n 1 2 respectively. If (V, G) is an extension of (A, G ) by (B, G ) then, under certain 1 2 choice of a basis in V, all elements of G are represented by (m + n) x (m + n) mat- rices of the form (*) ~1-~ ~-J lh I g2 I .