doc-src/Classes/classes.tex

 \begin{document}
 
 \maketitle
 
 \begin{abstract}
-  \noindent This tutorial introduces the look-and-feel of
-  Isar type classes to the end-user.  Isar type classes
+  \noindent This tutorial introduces Isar type classes, which 
   are a convenient mechanism for organizing specifications.
   Essentially, they combine an operational aspect (in the
   manner of Haskell) with a logical aspect, both managed uniformly.
 \end{abstract}