What is a Matroid?
Matroid is a structure $(E, F)$ where $E$ and $F$ are sets and elements of $E$ are ‘building’ the set $F$, which has the following properties: (A1): $\empty \in F$ (A2): If $X \subseteq Y$ and $Y \in F$ then $X \in F$ (A3): Let $X, Y \in F$ and $|X| < |Y|$ then $\exists y \in Y \backslash X$ such that $X \cup \ \{y\} \in F$ If $M$ is a matroid, then $E$ is called the ground set, elements of $F$ independent sets...