Induction representation of the center is not irreducible












1














Suppose $varphi: Z(G) to GL(V)$ is an irreducible representation of the center of a non-abelian group $G$. I want to show that $Ind^G_{Z(G)} varphi$ is not irreducible. Any hints?



So far, I have consider that $Z(G)$ is a normal subgroup. Moreover, the character is given by
$$
chi_{Ind^G_{Z(G)}} varphi(g) = Ind^G_{Z(G)}(g) = frac{1}{|Z(G)|} sum_{x in G} dot{chi}(x^{-1}gx).
$$










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  • It might be easiest to calculate the inner product of this character with itself. First, you should note that $x^{-1}gxin Z(G)$ implies $gin Z(G)$, which should simplify the calculation.
    – Tobias Kildetoft
    Nov 20 at 18:48










  • Thanks for the hint, that's quite helpful! I'm working on the computations right now.
    – Sigurd
    Nov 20 at 19:27
















1














Suppose $varphi: Z(G) to GL(V)$ is an irreducible representation of the center of a non-abelian group $G$. I want to show that $Ind^G_{Z(G)} varphi$ is not irreducible. Any hints?



So far, I have consider that $Z(G)$ is a normal subgroup. Moreover, the character is given by
$$
chi_{Ind^G_{Z(G)}} varphi(g) = Ind^G_{Z(G)}(g) = frac{1}{|Z(G)|} sum_{x in G} dot{chi}(x^{-1}gx).
$$










share|cite|improve this question






















  • It might be easiest to calculate the inner product of this character with itself. First, you should note that $x^{-1}gxin Z(G)$ implies $gin Z(G)$, which should simplify the calculation.
    – Tobias Kildetoft
    Nov 20 at 18:48










  • Thanks for the hint, that's quite helpful! I'm working on the computations right now.
    – Sigurd
    Nov 20 at 19:27














1












1








1







Suppose $varphi: Z(G) to GL(V)$ is an irreducible representation of the center of a non-abelian group $G$. I want to show that $Ind^G_{Z(G)} varphi$ is not irreducible. Any hints?



So far, I have consider that $Z(G)$ is a normal subgroup. Moreover, the character is given by
$$
chi_{Ind^G_{Z(G)}} varphi(g) = Ind^G_{Z(G)}(g) = frac{1}{|Z(G)|} sum_{x in G} dot{chi}(x^{-1}gx).
$$










share|cite|improve this question













Suppose $varphi: Z(G) to GL(V)$ is an irreducible representation of the center of a non-abelian group $G$. I want to show that $Ind^G_{Z(G)} varphi$ is not irreducible. Any hints?



So far, I have consider that $Z(G)$ is a normal subgroup. Moreover, the character is given by
$$
chi_{Ind^G_{Z(G)}} varphi(g) = Ind^G_{Z(G)}(g) = frac{1}{|Z(G)|} sum_{x in G} dot{chi}(x^{-1}gx).
$$







representation-theory characters






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asked Nov 20 at 17:52









Sigurd

480211




480211












  • It might be easiest to calculate the inner product of this character with itself. First, you should note that $x^{-1}gxin Z(G)$ implies $gin Z(G)$, which should simplify the calculation.
    – Tobias Kildetoft
    Nov 20 at 18:48










  • Thanks for the hint, that's quite helpful! I'm working on the computations right now.
    – Sigurd
    Nov 20 at 19:27


















  • It might be easiest to calculate the inner product of this character with itself. First, you should note that $x^{-1}gxin Z(G)$ implies $gin Z(G)$, which should simplify the calculation.
    – Tobias Kildetoft
    Nov 20 at 18:48










  • Thanks for the hint, that's quite helpful! I'm working on the computations right now.
    – Sigurd
    Nov 20 at 19:27
















It might be easiest to calculate the inner product of this character with itself. First, you should note that $x^{-1}gxin Z(G)$ implies $gin Z(G)$, which should simplify the calculation.
– Tobias Kildetoft
Nov 20 at 18:48




It might be easiest to calculate the inner product of this character with itself. First, you should note that $x^{-1}gxin Z(G)$ implies $gin Z(G)$, which should simplify the calculation.
– Tobias Kildetoft
Nov 20 at 18:48












Thanks for the hint, that's quite helpful! I'm working on the computations right now.
– Sigurd
Nov 20 at 19:27




Thanks for the hint, that's quite helpful! I'm working on the computations right now.
– Sigurd
Nov 20 at 19:27















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