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Decidability of residual finiteness for one-relator groups

Develop an algorithm that, given a finite one-relator presentation, decides whether the corresponding group is residually finite.

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Background

Residual finiteness is a central property with deep implications (e.g., hopficity and algorithmic consequences). Many one-relator groups are known to be residually finite via geometric and profinite techniques, but there is no general decision procedure known for this class.

References

Residual finiteness is, in general, a significantly weaker property than being free-by-cyclic, even in the class of one-relator groups. It remains an open problem whether residual finiteness is decidable for one-relator groups.

The theory of one-relator groups: history and recent progress (2501.18306 - Linton et al., 30 Jan 2025) in Subsection 5.6 (Free-by-cyclic one-relator groups)