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20182025
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math.GR2024

Characters and Sylow -subgroup abelianization

Eugenio Giannelli, Noelia Rizo, A. A. Schaeffer Fry +1

We characterize when a finite group G possesses a Sylow 3-subgroup P with abelianization of order 9 in terms of the number of height zero characters lying in the principal 3-block…

math.GR2023

Brauer's problem 21 for principal blocks

Alexander Moretó, Noelia Rizo, A. A. Schaeffer Fry

Problem 21 of Brauer's list of problems from 1963 asks whether for any positive integer k there are finitely many isomorphism classes of groups that occur as the defect group of a…

math.GR2023

The blocks with five irreducible characters

J. Miquel Martínez, Noelia Rizo, Lucia Sanus

Let be a finite group, a prime and a Brauer -block of with defect group . We prove that if the number of irreducible ordinary characters in is then $D…

math.GR2022

Principal blocks for different primes, II

Gabriel Navarro, Noelia Rizo, A. A. Schaeffer Fry

If G is a finite group, we have proposed new conjectures on the interaction between different primes and their corresponding Brauer principal blocks. In this paper, we give strong…

math.GR2022

Principal blocks for different primes, I

Gabriel Navarro, Noelia Rizo, A. A. Schaeffer Fry

We propose new conjectures about the relationship between the principal blocks of finite groups for different primes and establish evidence for these conjectures.

math.GR2021

Kernels of p'-degree irreducible characters

Alexander Moretó, Noelia Rizo

We prove a p'-version of a classical theorem of Broline and Garrison. As a consequence, we obtain results on p-parts of character codegrees.