Update 0-introduction.tex

blueprint/src/chapters/0-introduction.tex

@@ -183,7 +183,7 @@ \chapter{Introduction}
 \begin{proof}
     \leanok
     \uses{lmm:norm_lambda}
-    It directly follows from \Cref{lmm:norm_lambda} By the fundamental properties of ideals.
+    It directly follows from \Cref{lmm:norm_lambda} by the fundamental properties of ideals.
 \end{proof}
 
 \begin{lemma}