Relative Undecidability in Term Rewriting: I. The Termination Hierarchy.

Alfons Geser Aart Middeldorp Enno Ohlebusch Hans Zantema Relative Undecidability in Term Rewriting: I. The Termination Hierarchy. 101-131 2002 178 Inf. Comput. 1 http://dx.doi.org/10.1006/inco.2002.3120 db/journals/iandc/iandc178.html#GeserMOZ02