removed redundant expansion tree

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@1639 85d21ef8-add0-11de-ae77-5bfb9c5a3f34
fixed redundancy in ET

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@1640 85d21ef8-add0-11de-ae77-5bfb9c5a3f34