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Ali Taghavi
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Finite ( or discrete) group theory and statistic: a possible generalization of character group via covariance

Assume that $G$ is a finite group. Let $\phi=X+iY: G\to S^1$ be a complex function of unit norm. We consider $G$ as a sample (probability) space with the normalized counting measure $\mu(A)=\frac{n(A)}{|G|}$. So we consider $X,Y$ as two random variables. Their covariance is denoted by $Cov(X,Y)$.

Is the following set $H$ a group with the operation of pointwise multiplication $\phi \psi(x)=\phi(x).\psi(x)$?

$$H=\bigm\{\phi=X+iY:G\to S^1 \bigm| ( \phi\equiv1) \vee \bigm(\sum_g \phi(g)=0 \wedge Cov(X,Y)=0 \bigm ) \bigm \}$$

Remark 1: Evry character $\phi:G\to S^1=\mathbb{T}$ obviousely belongs to $H$. So this question is an attempt to find a generalization of characters in group theory in the context of probability and statistics.

Remark 2: What about if we remove the condition $\sum_g \phi(g)=0$ from the definition of the above $H$?

Ali Taghavi
  • 356
  • 8
  • 31
  • 123