40 research outputs found
A combinatorial proof of a plethystic Murnaghan--Nakayama rule
This article gives a combinatorial proof of a plethystic generalization of
the Murnaghan--Nakayama rule. The main result expresses the product of a Schur
function with the plethysm as an integral linear combination of
Schur functions. The proof uses a sign-reversing involution on sequences of
bead moves on James' abacus, inspired by the arguments in N. Loehr, Abacus
proofs of Schur function identities, SIAM J. Discrete Math. 24 (2010),
1356-1370.Comment: 9 pages, 2 figures, expanded and revised versio
On the complexity of computing Kronecker coefficients
We study the complexity of computing Kronecker coefficients
. We give explicit bounds in terms of the number of parts
in the partitions, their largest part size and the smallest second
part of the three partitions. When , i.e. one of the partitions
is hook-like, the bounds are linear in , but depend exponentially on
. Moreover, similar bounds hold even when . By a separate
argument, we show that the positivity of Kronecker coefficients can be decided
in time for a bounded number of parts and without
restriction on . Related problems of computing Kronecker coefficients when
one partition is a hook, and computing characters of are also considered.Comment: v3: incorporated referee's comments; accepted to Computational
Complexit
A Murnaghan-Nakayama rule for Grothendieck polynomials of Grassmannian type
We consider the Grothendieck polynomials appearing in the K-theory of
Grassmannians, which are analogs of Schur polynomials. This paper aims to
establish a version of the Murnaghan-Nakayama rule for Grothendieck polynomials
of the Grassmannian type. This rule allows us to express the product of a
Grothendieck polynomial with a power sum symmetric polynomial into a linear
combination of other Grothendieck polynomials.Comment: 10 pages, 7 figure
Murnaghan-Nakayama Rule The Explanation and Usage of the Algorithm
Character values are not the easiest to calculate, so it is important to find good algorithms that can help ease these calculations. In the 20th century, the two mathematicians Murnaghan and Nakayama developed a rule that calculates character values for partitions on some computations. This rule has later been given the name The Murnaghan-Nakayama rule, after these two authors.
The Murnaghan-Nakayama rule is a combinatorial method for computing character values of irreducible representations of symmetric groups. This makes this rule an important part of representation theory. One of the versions of this rule is stated in the recursive Murnaghan-Nakayama rule. Where, in this version, we can use border strips and diagrams to calculate the character values of representations on a given composition. This algorithm is quite fast in these calculations.
The Murnaghan-Nakayama rule can also be considered a central algorithm in representation theory over symmetric groups. It is a fascinating and powerful algorithm that has a strong connection to both combinatorics and representation theory
The combinatorics of Jeff Remmel
We give a brief overview of the life and combinatorics of Jeff Remmel, a mathematician with successful careers in both logic and combinatorics