fixed "sl" style;

--- a/lib/texinputs/isabelle.sty	Fri Sep 15 16:29:36 2000 +0200
+++ b/lib/texinputs/isabelle.sty	Fri Sep 15 16:30:16 2000 +0200
@@ -129,4 +129,8 @@
 \renewcommand{\isacharbraceright}{\emph{$\}$}}%
 }
 
-\newcommand{\isabellestylesl}{\isabellestyleit\renewcommand{\isastyle}{\small\slshape}}
+\newcommand{\isabellestylesl}{%
+\isabellestyleit%
+\renewcommand{\isastyle}{\small\sl}%
+\renewcommand{\isastyleminor}{\sl}%
+}