algebra / Geometric group theory: amenable and simple groups

Is there an infinite finitely presented simple amenable group?

Theorem 1.1: there exists an infinite finitely presented simple amenable group. It is an alternating subgroup of a polygon exchange group (piecewise translations of finitely many squares over a real quadratic ring, with two inclined edge directions besides the coordinate ones). Finite presentation comes from propagating relations over a fixed finite generating set with a homological argument in the style of Szymik-Wahl; amenability from correlated random polygonal partitions giving almost-invariant measures. No explicit bound on the sizes of the generating set or relators is given.

40Significance / 100
1Frontier events
0Verification tasks
0Recorded attempts

Temporal state

Current frontier

No reconciled state yet.

Append-only history

Frontier timeline

algebraSep 23, 2026Significance 40/100Registry: lean checked

Is there an infinite finitely presented simple amenable group?

Prior state unknown→proved

Theorem 1.1: there exists an infinite finitely presented simple amenable group. It is an alternating subgroup of a polygon exchange group (piecewise translations of finitely many squares over a real quadratic ring, with two inclined edge directions besides the coordinate ones). Finite presentation comes from propagating relations over a fixed finite generating set with a homological argument in the style of Szymik-W…

SourceReplayReproducedFormal proofStatement auditExternal checkExpert reviewPeer review

Research memory

Claims and attempts

Scoped claims

Source authenticated

Theorem 1.1: there exists an infinite finitely presented simple amenable group. It is an alternating subgroup of a polygon exchange group (piecewise translations of finitely many squares over a real quadratic ring, with two inclined edge directions besides the coordinate ones). Finite presentation comes from propagating relations over a fixed finite generating set with a homological argument in the style of Szymik-Wahl; amenability from correlated random polygonal partitions giving almost-invariant measures. No explicit bound on the sizes of the generating set or relators is given.

Theorem 1.1: there exists an infinite finitely presented simple amenable group. It is an alternating subgroup of a polygon exchange group (piecewise translations of finitely many squares over a real quadratic ring, with two inclined edge directions besides the coordinate ones). Finite presentation comes from propagating relations over a fixed finite generating set with a homological argument in the style of Szymik-Wahl; amenability from correlated random polygonal partitions giving almost-invariant measures. No explicit bound on the sizes of the generating set or relators is given.

Recorded attempts

Evidence graph

Connected research record

Is there an infinite finitely presented simple amenable group? — Mathematical Frontier Network