Tetrad VERSION, Copyright (C) 1998, 1999, 2000, 2001, 2002,
2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 by Peter Spirtes,
Richard Scheines, Joseph Ramsey, and Clark Glymour. Tetrad VERSION
comes with ABSOLUTELY NO WARRANTY; for details select "Warranty"
from the Help menu. This is free software, and you are welcome to
redistribute it under certain conditions; select "License" in the
Help menu for details.