--- a/ChengsongTanPhdThesis/Chapters/Finite.tex	Mon Jul 10 01:51:46 2023 +0100
+++ b/ChengsongTanPhdThesis/Chapters/Finite.tex	Mon Jul 10 01:53:32 2023 +0100
@@ -218,6 +218,11 @@
 if we omit the way these regular expressions need to be nested.
 where each $r_i$ ($i \in \{1, \ldots, n\}$) is related to some fragments
 of $r$ and $s$.
+We call the precise formalisation for the shape of 
+\[
+ r_1 + r_2 + r_3 + \ldots + r_n
+\]
+"closed form".
 The second important observation is that the list %of regular expressions
 $[r_1, \ldots, r_n]$ %is not
 cannot grow indefinitely because they all come from $r$, and derivatives