# 2020

# Box-ball systems and RSK tableaux

**Séminaire Lotharingien de Combinatoire (2021)**

Sém. Lothar. Combin.85B(2021), Art. 14, 12 pp.

**Proceedings of the 33rd Conference on Formal Power****Series and Algebraic Combinatorics ****Ben Drucker, Eli Garcia, Emily Gunawan, and Rose Silver**

A box-ball system is a collection of discrete time states representing a permutation,

on which there is an action called a BBS move. After a finite number of BBS moves

the system decomposes into a collection of soliton states; these are weakly

increasing and invariant under BBS moves. The students proved that when this

collection of soliton states is a Young tableau or coincides with a partition of a type

described by Robinson-Schensted (RS), then it is an RS insertion tableau. They also

studied the number of steps required to reach this state.

# Resistance scaling on affine carpets

## Group Members

Samantha Forshay, Leng Mawi, Matthew Peeks.

## Supervisors

Chris Hayes, Luke Rogers, Sasha Teplyaev.

## Overview

A celebrated result in analysis and probability on fractals is the construction of a diffusion on the standard Sierpinski Carpet by Barlow and Bass. One key part of their argument is a pair of upper and lower estimates for the resistances of precarpets: if \(K_n\) denotes the level \(n\) approximation of the carpet and \(E_n\) is the minimal Dirichlet energy of a function that is identically 1 on one side of the carpet and identically 0 on the other side, then there are constants \(0<c\leq C< \infty\) so that \(c\rho^n\leq E_n\leq C\rho^n\). Estimates for \(\rho\) are known but the exact value is not.

The Sierpinski-type carpets to which the preceding estimates of resistance have been extended are all self-similar. By contrast, in the setting of post-critically finite fractals, resistance scaling has been successfully studied also in the self-affine case, initially by Fitzsimmons, Hambly and Kumagai.

The goal of this project was to investigate what aspects of the Barlow-Bass approach to resistance estimation on carpets could be extended to the self-affine case, and to make numerical computations of the behavior of resistance in this setting and its dependence on the affine scalings.