--- a/lib/texinputs/isabellesym.sty Tue Dec 29 19:11:23 2015 +0100
+++ b/lib/texinputs/isabellesym.sty Tue Dec 29 20:58:18 2015 +0100
@@ -158,8 +158,12 @@
\newcommand{\isasymint}{\isamath{\mathsf{Z}\mkern-7.5mu\mathsf{Z}}}
\newcommand{\isasymleftarrow}{\isamath{\leftarrow}}
\newcommand{\isasymlongleftarrow}{\isamath{\longleftarrow}}
+\newcommand{\isasymlonglongleftarrow}{\isamath{\xleftarrow{\hphantom{AAA}}}} %requires amsmath
+\newcommand{\isasymlonglonglongleftarrow}{\isamath{\xleftarrow{\hphantom{AAAA}}}} %requires amsmath
\newcommand{\isasymrightarrow}{\isamath{\rightarrow}}
\newcommand{\isasymlongrightarrow}{\isamath{\longrightarrow}}
+\newcommand{\isasymlonglongrightarrow}{\isamath{\xrightarrow{\hphantom{AAA}}}} %requires amsmath
+\newcommand{\isasymlonglonglongrightarrow}{\isamath{\xrightarrow{\hphantom{AAAA}}}} %requires amsmath
\newcommand{\isasymLeftarrow}{\isamath{\Leftarrow}}
\newcommand{\isasymLongleftarrow}{\isamath{\Longleftarrow}}
\newcommand{\isasymRightarrow}{\isamath{\Rightarrow}}