SF bug #803842: Wrong description of regexp concatenation
diff --git a/Doc/lib/libre.tex b/Doc/lib/libre.tex
index 1aaebd9..7368ab4 100644
--- a/Doc/lib/libre.tex
+++ b/Doc/lib/libre.tex
@@ -51,10 +51,11 @@
Regular expressions can be concatenated to form new regular
expressions; if \emph{A} and \emph{B} are both regular expressions,
-then \emph{AB} is also a regular expression. If a string \emph{p}
-matches A and another string \emph{q} matches B, the string \emph{pq}
-will match AB if \emph{A} and \emph{B} do no specify boundary
-conditions that are no longer satisfied by \emph{pq}. Thus, complex
+then \emph{AB} is also a regular expression. In general, if a string
+\emph{p} matches \emph{A} and another string \emph{q} matches \emph{B},
+the string \emph{pq} will match AB. This holds unless \emph{A} or
+\emph{B} contain low precedence operations; boundary conditions between
+\emph{A} and \emph{B}; or have numbered group references. Thus, complex
expressions can easily be constructed from simpler primitive
expressions like the ones described here. For details of the theory
and implementation of regular expressions, consult the Friedl book