Confluence of Length Preserving String Rewriting Systems is Undecidable
Yi Wang, Masahiko Sakai, Naoki Nishida, Toshiki Sakabe, Keiichirou Kusakari · Institutional Repositories DataBase (IRDB) · 2007
This paper shows the undecidability of confluence for length preserving string rewriting systems. It is proven by reducing the Post's correspondence problem(PCP), which is known to be undecidable, to confluence problem for length preserving string rewriting systems. More precisely, we designed a reduction algorithm having the property that the existence of a solution for a given instance of PCP concides with the non-confluence of the string rewriting system obtained from the reduction algorithm.