echo "<gen>"
while read line
do
if [[ $line == *.\ * ]]; then
  segline=$(echo $line | sed s/"\. "/".~"/)
  sentence="$( cut -d '~' -f 1 <<< "$segline" )"
  rulelist="$( cut -d '~' -f 2- <<< "$segline" )"
else
  sentence=$line; 
  rulelist=""; 
fi
  printf "<pair><sent>$sentence</sent><rules>"
  for r in $rulelist
   do printf "<rule>$r</rule>"
   done
  echo "</rules></pair>"
done;
echo "</gen>"