Let $G = (V,E)$ be a finite graph, and let $M(G)$ be the cycle matroid of $G$ on ground set $E$. A subset $C \subseteq E$ is a cocircuit of $M(G)$ if and only if $C$ is a bond of $G$, that is, a nonempty inclusion-minimal edge cut of the form
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\begin{align*}
\delta_G(X) = \{e \in E : e \text{ has one endpoint in } X \text{ and one endpoint in } V \setminus X\}
\end{align*}