An Atlas of Orthogonal Representations
摘要
Let G be a finite group and \(\rho : G \rightarrow {{\,\textrm{GL}\,}}(2n, F)\) be an absolutely irreducible orthogonal representation of even degree over a finite field F. Then \(\rho (G)\) embeds into \({{\,\textrm{GO}\,}}^+(2n, F)\) or \({{\,\textrm{GO}\,}}^-(2n, F)\) . We describe methods to decide which case holds for \(\rho \) , and use them to determine most of the orthogonal discriminants of the absolutely irreducible orthogonal representations of even degree that are listed in the ATLAS of Finite Groups [2].