Geodesic
Bound on the Jordan type of a generic nilpotent matrix commuting with a given matrix
Journal of Algebraic Combinatorics, Tome 38 (2013) no. 4, pp. 947-972.

Voir la notice de l'article provenant de la source Electronic Library of Mathematics

It is well known that a nilpotent $n\times n$ matrix $B$ is determined up to conjugacy by a partition of $n$ formed by the sizes of the Jordan blocks of $B$. We call this partition the Jordan type of $B$. We obtain partial results on the following problem: for any partition $P$ of $n$ describe the type $Q(P)$ of a generic nilpotent matrix commuting with a given nilpotent matrix of type $P$. A conjectural description for $Q(P)$ was given by P. Oblak and restated by L. Khatami. In this paper we prove "half" of this conjecture by showing that this conjectural type is less than or equal to $Q(P)$ in the dominance order on partitions.
Classification : 15A27
Keywords: Jordan type, nilpotent matrix, commutator, partition 
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     title = {Bound on the {Jordan} type of a generic nilpotent matrix commuting with a given matrix},
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Iarrobino, Anthony; Khatami, Leila. Bound on the Jordan type of a generic nilpotent matrix commuting with a given matrix. Journal of Algebraic Combinatorics, Tome 38 (2013) no. 4, pp. 947-972. http://geodesic.mathdoc.fr/item/JAC_2013__38_4_a2/