Published online by Cambridge University Press: 28 March 2014
We show that the modules for the Frobenius kernel of a reductive algebraic group over
an algebraically closed field of positive characteristic $p$ induced from the
$p$-regular blocks of its parabolic subgroups can be
$\mathbb{Z}$-graded. In particular, we obtain that the modules induced from the
simple modules of
$p$-regular highest weights are rigid and determine their Loewy series,
assuming the Lusztig conjecture on the irreducible characters for the reductive
algebraic groups, which is now a theorem for large
$p$. We say that a module is rigid if and only if it admits a unique
filtration of minimal length with each subquotient semisimple, in which case the
filtration is called the Loewy series.