p-radical subgroup
= p-radical subgroup
{title2=$D=O_p(N_G(D))$}
A <p-subgroup> is p-radical if it equals the <p-core> of its <normalizer>. Every <defect group of a block> is p-radical by <defect groups are centralizer-conjugate Sylow intersections>. Being an intersection of arbitrary Sylow subgroups alone is weaker than the <centralizer>-conjugate statement used in that argument.