# Definition:Circuit Axioms (Matroid)

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## Definition

Let $S$ be a finite set.

Let $\mathscr C$ be a non-empty set of subsets of $S$.

$\mathscr C$ is said to satisfy the circuit axioms if and only if:

 $(C1)$ $:$ $\displaystyle \forall C_1, C_2 \in \mathscr C:$ $\displaystyle C_1 \neq C_2 \implies C_1 \not \subseteq C_2$ $(C2)$ $:$ $\displaystyle \forall C_1, C_2 \in \mathscr C:$ $\displaystyle C_1 \neq C_2 \land z \in C_1 \cap C_2 \implies \exists C_3 \in \mathscr C : C_3 \subseteq \paren{C_1 \cup C_2} \setminus \set z$