In order to define the contension measure $\mathcal{I}_{c}$ we need to consider three-valued interpretations for propositional logic [Priest:1979]. A three-valued interpretation $\upsilon$ on $\mathsf{At}$ is a function $\upsilon:\mathsf{At}\rightarrow\{T,F,B\}$ where the values $T$ and $F$ correspond to the classical truth values $\mathsf{true}$ and $\mathsf{false}$, respectively. The additional truth value $B$ stands for both and is meant to represent a conflicting truth value for a proposition. The function $\upsilon$ is extended to arbitrary formulas as shown in the following table

Then, an interpretation $\upsilon$ satisfies a formula $\alpha$, denoted by $\upsilon\models^{3}\alpha$ if either $\upsilon(\alpha)=T$ or $\upsilon(\alpha)=B$. The contension inconsistency measure $\mathcal{I}_{c}$ is defined as \[ \mathcal{I}_{c}(\mathcal{K}) =\min\{|\upsilon^{-1}(B)|\mid\upsilon\models^{3}\mathcal{K}\} \] The contension inconsistency measure has been discussed in e.g. [Grant:2011].