Let $\mathcal{K}$ be a knowledge base. For a literal $x$ a minimal proof in $\mathcal{K}$ is a set $\pi\subseteq\mathcal{K}$ such that 1. $x$ is mentioned in $\pi$, 2. $\pi\models x$, and 3. $\pi$ is minimal wrt. set inclusion (note that $\pi$ has not to be consistent). Let $P_m(x)$ be the set of all minimal proofs of $x$ in $\mathcal{K}$. Then the Pm inconsistency measure $\mathcal{I}_{P_m}$ is defined as
\[
\mathcal{I}_{P_m}(\mathcal{K}) = \sum_{a\in \mathsf{At}}|P_m(a)|\cdot|P_m(\neg a)|
\]
The Pm inconsistency measure has been proposed in [Jabbour:2013]. Note that the above definition is not the original definition but a characterization also provided in [Jabbour:2013].