Finite unambiguity does not serve as an adequate definition of unambiguity that is equivalent to unambiguity as subterminality and unambiguity as a unique map. However, the definition attempted via finite unambiguity can be refined to something that is equivalent to these.

A grammar $𝐴$ is unambiguous if $\mathrm{\Delta }:𝐴⊢𝐴\&𝐴$ is an isomorphism. Equivalently, $𝐴$ is unambiguous if ${𝜋}_1:𝐴\&𝐴⊢𝐴$ and ${𝜋}_2:𝐴\&𝐴⊢𝐴$ are equal.