# FlagMatroid -- the class of all flag matroids

## Description

A flag matroid $\mathbf M$ is an ordered list $\{M_1, \ldots, M_k\}$ of Matroids on a common ground set such that $M_i$ is a matroid quotient of $M_{i+1}$ for all $i=1, \ldots, k-1$. The matroids $M_i$'s are called the "constituent" matroids of the flag matroid $\mathbf M$. The class FlagMatroid is a HashTable with two keys:

• groundSet, whose value is a Set representing the common ground set of the constituent matroids
• constituents, whose value is a List of Matroids

## Caveat

Flag matroids are the first examples beyond ordinary matroids of a more general combinatorial family known as Coxeter matroids. Coxeter matroids have not been implemented yet.