Jörg Endrullis Johannes Waldmann Hans Zantema Matrix Interpretations for Proving Termination of Term Rewriting. 195-220 2008 40 J. Autom. Reasoning 2-3 http://dx.doi.org/10.1007/s10817-007-9087-9 db/journals/jar/jar40.html#EndrullisWZ08