Post Embedding Problem Is Not Primitive Recursive, with Applications to Channel Systems
- Cite this paper as:
- Chambart P., Schnoebelen P. (2007) Post Embedding Problem Is Not Primitive Recursive, with Applications to Channel Systems. In: Arvind V., Prasad S. (eds) FSTTCS 2007: Foundations of Software Technology and Theoretical Computer Science. FSTTCS 2007. Lecture Notes in Computer Science, vol 4855. Springer, Berlin, Heidelberg
We introduce PEP, the Post Embedding Problem, a variant of PCP where one compares strings with the subword relation, and PEPreg, a further variant where solutions are constrained and must belong to a given regular language. PEPreg is decidable but not primitive recursive. This entails the decidability of reachability for unidirectional systems with one reliable and one lossy channel.
KeywordsPost correspondence problem Lossy channel systems Higman’s Lemma
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