Marked PCP is decidable



: Halava V, Hirvensalo M, de Wolf R

Publisher: ELSEVIER SCIENCE BV

: 2001

Theoretical Computer Science

THEORETICAL COMPUTER SCIENCE

: THEOR COMPUT SCI

: 255

: 1-2

: 193

: 204

: 12

: 0304-3975

DOI: https://doi.org/10.1016/S0304-3975(99)00163-2


We show that the marked version of the Post Correspondence Problem, where the words on a list are required to differ in the first letter, is decidable. On the other hand, we prove that the PCP remains undecidable if we only require the words to differ in the first two letters. Thus we locate the decidability/undecidability-boundary between marked and 2-marked PCP. (C) 2001 Elsevier Science B.V. All rights reserved.



Last updated on 2025-13-10 at 14:26