--- a/lib/texinputs/isabellesym.sty Tue Dec 29 20:58:18 2015 +0100
+++ b/lib/texinputs/isabellesym.sty Tue Dec 29 21:51:58 2015 +0100
@@ -166,8 +166,10 @@
\newcommand{\isasymlonglonglongrightarrow}{\isamath{\xrightarrow{\hphantom{AAAA}}}} %requires amsmath
\newcommand{\isasymLeftarrow}{\isamath{\Leftarrow}}
\newcommand{\isasymLongleftarrow}{\isamath{\Longleftarrow}}
+\newcommand{\isasymLleftarrow}{\isamath{\Lleftarrow}} %requires amssymb
\newcommand{\isasymRightarrow}{\isamath{\Rightarrow}}
\newcommand{\isasymLongrightarrow}{\isamath{\Longrightarrow}}
+\newcommand{\isasymRrightarrow}{\isamath{\Rrightarrow}} %requires amssymb
\newcommand{\isasymleftrightarrow}{\isamath{\leftrightarrow}}
\newcommand{\isasymlongleftrightarrow}{\isamath{\longleftrightarrow}}
\newcommand{\isasymLeftrightarrow}{\isamath{\Leftrightarrow}}