Dice Question Streamline Icon: https://streamlinehq.com

Decision problems for two‑relator groups

Determine the decidability of the word problem, the conjugacy problem, and the isomorphism problem for finitely presented two‑relator groups.

Information Square Streamline Icon: https://streamlinehq.com

Background

Unlike the one‑relator case (word problem solved by Magnus), the two‑relator setting lacks any general positive results: the core decision problems are unsolved. The authors emphasize that even finiteness classification is open, underscoring the gap between one‑ and two‑relator theories.

A resolution would be a major advance in combinatorial and geometric group theory.

References

The word problem, conjugacy problem, and isomorphism problem are all open for two-relator groups.

The theory of one-relator groups: history and recent progress (2501.18306 - Linton et al., 30 Jan 2025) in Section 8.4 (Two‑relator groups)