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General isomorphism problem for one-relator groups

Determine whether the isomorphism problem is decidable for the class of all one-relator groups, i.e., given two finite one-relator presentations, decide algorithmically whether the resulting groups are isomorphic.

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Background

The isomorphism problem for finitely presented groups is undecidable in general, but for many structured classes it can be decided. While there are solutions for particular subclasses of one-relator groups (e.g., torsion or center cases), a complete resolution for all one-relator groups remains elusive.

References

Finally, in \S(1980) we go further in-depth on some decision problems for one-relator groups, including the conjugacy problem, the isomorphism problem (both of which remain open in general), and the complexity of the word problem.

The theory of one-relator groups: history and recent progress (2501.18306 - Linton et al., 30 Jan 2025) in Section 8, Decision problems (1960–1980)