docs: Units no longer have to be discrete.

docs/algebra.tex

@@ -168,7 +168,6 @@ This operation is needed to prove that $\later$ commutes with separating conjunc
   \item $\munit$ is valid: \\ $\All n. \munit \in \mval_n$
   \item $\munit$ is a left-identity of the operation: \\
     $\All \melt \in M. \munit \mtimes \melt = \melt$
-  \item $\munit$ is a discrete COFE element
   \item $\munit$ is its own core: \\ $\mcore\munit = \munit$
   \end{enumerate}
 \end{defn}