We show that bigrassmannian permutations determine the socle of the cokernel of an
inclusion of Verma modules in type A. All such socular constituents turn out to be indexed by …

A Coxeter group is said to be\emph {$\mathbf {a}(2) $-finite} if it has finitely many elements of
$\mathbf {a} $-value 2 in the sense of Lusztig. In this paper, we give explicit combinatorial …