*[ is translation-invariant, hence commutes with translations and hence with convolutions. -T.]*

*[Corrected, thanks – T.]*

A minimal idempotent takes the form for some irreducible character . One can then simplify as for any from the Fourier inversion formula for characters, so the first sum in Lemma 5 simplifies to . It turns out in fact that in the irreducible case, the quantity in Lemma 5 vanishes when is an exceptional character associated with a character in , and is equal to 1 otherwise (this is basically the content of Lemma 6).

]]>“A Frobenius group is a transitive permutation group on a finite set, such that no non-trivial element fixes more than one point and some non-trivial element fixes a point.”

And then it says the Dihedral group is an example of a Frobenius group. And the groups of transformations

—

Lemma 5 is very interesting. I thought when is a character it was always zero.

]]>*[Fixed properly this time, thanks – T.]*

“with Frobenius complement H and Frobenius complement K.” <– Frob. kernel K.

*[Corrected, thanks – T.]*