The Hurwitz Equivalence Problem Is Undecidable
نویسنده
چکیده
In this paper, we prove that the Hurwitz equivalence problem for 1-factorizations in F2⊕F2 is undecidable, and as a consequence, the Hurwitz equivalence problem for ∆-factorizations in the braid groups Bn, n ≥ 5 is also undecidable.
منابع مشابه
The Simplest Language Where Equivalence of Finite Substitutions Is Undecidable
We show that it is undecidable whether two finite substitutions agree on the binary language a∗b. This in particular means that equivalence of nondeterministic finite transducers is undecidable even for two-state transducers with unary input alphabet and whose all transitions start from the initial state.
متن کاملSimulation Preorder on Simple Process Algebras
We consider the problem of simulation preorder/equivalence between infinite-state processes and finite-state ones. We prove that simulation preorder (in both directions) and simulation equivalence are intractable between all major classes of infinite-state systems and finite-state ones. This result is obtained by showing that the problem whether a BPA (or BPP) process simulates a finitestate on...
متن کاملIdealized Algol with Ground Recursion, and DPDA Equivalence
We prove that observational equivalence of IA3 + Y0 (3rdorder Idealized Algol with 0th-order recursion) is equivalent to the DPDA Equivalence Problem, and hence decidable. This completes the classification of decidable fragments of Idealized Algol. We also prove that observational approximation of IA1 + Y0 is undecidable by reducing the DPDA Containment Problem to it.
متن کاملUndecidability of 2-Label BPP Equivalences and Behavioral Type Systems for the pi -Calculus
The trace equivalence of BPP was shown to be undecidable by Hirshfeld. We show that the trace equivalence remains undecidable even if the number of labels is restricted to two. The undecidability result holds also for the simulation of two-label BPP processes. These results imply undecidability of some behavioral type systems for the π-calculus.
متن کاملUndecidability of 2-Label BPP Equivalences and Behavioral Type Systems for the π-Calculus
The trace equivalence of BPP was shown to be undecidable by Hirshfeld. We show that the trace equivalence remains undecidable even if the number of labels is restricted to two. The undecidability result holds also for the simulation of two-label BPP processes. These results imply undecidability of some behavioral type systems for the π-calculus.
متن کامل