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In 2000, Dergachev and Kirillov introduced subalgebras of "seaweed type" in $\mathfrak{gl}(n)$ and computed their index using certain graphs. In this article, those graphs are called type-A meander graphs. Then the subalgebras of seaweed…

Representation Theory · Mathematics 2017-02-28 Dmitri Panyushev , Oksana Yakimova

In 2000, Dergachev and Kirillov introduced subalgebras of "seaweed type" in $\mathfrak{gl}_n$ and computed their index using certain graphs. Then seaweed subalgebras $\mathfrak q\subset\mathfrak g$ were defined by Panyushev for any…

Representation Theory · Mathematics 2025-04-03 Oksana Yakimova

We give an upper bound for the index of certain Lie algebras, called of seaweed type, introduced by V. Dergachev, A. Kirillov and D. Panyushev. We deduce from this a conjecture of D. Panyushev stated in "Inductive formulas for the index of…

Representation Theory · Mathematics 2007-05-23 Patrice Tauvel , Rupert W. T. Yu

The index of a Lie algebra is an important algebraic invariant. In 2000, Vladimir Dergachev and Alexandre Kirillov defined seaweed subalgebras of $\mathfrak{gl}_n$ (or $\mathfrak{sl}_n$) and provided a formula for the index of a seaweed…

Combinatorics · Mathematics 2019-11-01 Seunghyun Seo , Ae Ja Yee

The index of a seaweed Lie algebra can be computed from its associated meander graph. We examine this graph in several ways with a goal of determining families of Frobenius (index zero) seaweed algebras. Our analysis gives two new families…

Representation Theory · Mathematics 2011-06-21 Vincent Coll , Anthony Giaquinto , Colton Magnant

The index of a Lie algebra is an important algebraic invariant, but it is notoriously difficult to compute. However, for the suggestively-named seaweed algebras, the computation of the index can be reduced to a combinatorial formula based…

Rings and Algebras · Mathematics 2022-04-15 Alex Cameron , Vincent E. Coll , Nicholas Mayers , Nicholas Russoniello

Analogous to the types A, B, and C cases, we address the computation of the index of seaweed subalgebras in the type-D case. Formulas for the algebra's index can be computed by counting the connected components of its associated meander. We…

Rings and Algebras · Mathematics 2019-08-09 Alex Cameron , Vincent E. Coll, , Matthew Hyatt

Seaweed algebras are a class of Lie algebras that are naturally characterized by a pair of compositions, which in turn are represented visually as planar graphs called meanders. These meanders provide a straightforward method for computing…

Combinatorics · Mathematics 2025-12-10 Kassie Archer , Aaron Geary , Robert P. Laudone

Analogous to the sl(n) case, we address the computation of the index of seaweed subalgebras of sp(2n) by introducing graphical representations called symplectic meanders. Formulas for the algebra's index may be computed by counting the…

Rings and Algebras · Mathematics 2016-02-04 Vincent E. Coll, , Matthew Hyatt , Colton Magnant

We give some properties on the index of seaweed subalgebras of the complex Lie algebra $\mathfrak{gl}(n)$ which allow to obtain formulas for the index of some interesting classes of this family and to give new families of Frobenius Lie…

Representation Theory · Mathematics 2019-04-25 Meher Bouhani

We generalize the results in [2] giving a reduction algorithm allowing to compute the index of seaweed subalgebras of classical simple Lie algebras. We thus are able to obtain the index of some interesting families of seaweed subalgebras…

Representation Theory · Mathematics 2019-12-09 Meher Bouhani

A celebrated result of Gromov ensures the existence of a contact structure on any connected, non-compact, odd dimensional Lie group. In general, such structures are not invariant under left translation. The problem of finding which Lie…

Rings and Algebras · Mathematics 2023-06-12 Vincent E. Coll, , Nicholas Russoniello

The index of a Lie algebra $\mathfrak{g}$ is defined by ind $\mathfrak{g}=$ $\min_{f\in \mathfrak{g}^*}\dim(\ker (B_f))$, where $f$ is an element of the linear dual $\mathfrak{g}^*$ and $B_f(x,y)=f([x,y])$ is the associated skew-symmetric…

Rings and Algebras · Mathematics 2020-04-13 Vincent E. Coll, , Aria L. Dougherty

Seaweed subalgebras of $\mathfrak{gl}(n,\mathbb{C})$ and $\mathfrak{sl}(n,\mathbb{C})$ are combinatorially defined matrix Lie algebras whose index admits a closed-form description in terms of an associated graph called a meander. In this…

Combinatorics · Mathematics 2026-02-17 Vincent E. Coll , Nicholas Mayers

This paper is a continuation of earlier work on the construction of contact forms on seaweed algebras. In the prequel to this paper, we show that every index-one seaweed subalgebra of $A_{n-1}=\mathfrak{sl}(n)$ is contact by identifying…

Rings and Algebras · Mathematics 2023-06-12 Vincent E. Coll, , Nicholas Russoniello

If $\mathfrak{g}$ is a Frobenius Lie algebra, then the spectrum of $\mathfrak{g}$ is an algebraic invariant equal to the multiset of eigenvalues corresponding to a particular operator acting on $\mathfrak{g}$. In the case of Frobenius…

Combinatorics · Mathematics 2023-06-21 Nicholas Mayers , Nicholas Russoniello

We provide a recursive classification of meander graphs, showing that each meander is identified by a unique sequence of fundamental graph-theoretic moves. This sequence is called the meander's signature. The signature not only provides a…

Quantum Algebra · Mathematics 2012-07-05 Vincent Coll , Colton Magnant , Hua Wang

A standard seaweed subalgebra of $A_{n-1}=\mathfrak{sl}(n)$ may be parametrized by a pair of compositions of the positive integer $n$. For all $n$ and certain $k(n)$, we provide closed-form formulas and the generating functions for $C(n,k)$…

Combinatorics · Mathematics 2018-08-06 Vincent E. Coll, , Aria Dougherty , Matthew Hyatt , Andrew W. Mayers , Nick W. Mayers

Using the index theory of seaweed algebras, we explore various new integer partition statistics. We find relations to some well-known varieties of integer partitions as well as a surprising periodicity result.

Combinatorics · Mathematics 2018-10-10 Vincent Coll , Andrew Mayers , Nick Mayers

A ($2k+1$)$-$dimensional contact Lie algebra is one which admits a one-form $\varphi$ such that $\varphi \wedge (d\varphi)^k\ne0$. Such algebras have index one, but this is not generally a sufficient condition. Here we show that index-one…

Rings and Algebras · Mathematics 2022-10-19 Vincent E. Coll , Nicholas Mayers , Nicholas Russoniello , Gil Salgado
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