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.