algebra / L2-invariants; Fuglede-Kadison determinants over group von Neumann algebras

The group-ring Determinant Conjecture (Luck)

Theorem 1.1: a finitely generated group GDG_D, n≥1n\ge1 and A∈Mn(Z[GD])A\in M_n(\mathbb Z[G_D]), invertible over Q[GD]\mathbb Q[G_D] with bounded inverse, whose Fuglede-Kadison determinant lies strictly between 00 and 11; the log integral is finite and negative. The group is nonsofic by Elek-Szabo. It disproves the unrestricted conjecture only; it says nothing about torsion-free groups, groups satisfying the Atiyah conjecture, or the determinant approximation conjecture, and it relies on the characteristic-two direct-finiteness counterexample.

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algebraSep 23, 2026Significance 35/100Registry: lean checked

The group-ring Determinant Conjecture (Luck)

Prior state unknown→disproved

Theorem 1.1: a finitely generated group GDG_D, n≥1n\ge1 and A∈Mn(Z[GD])A\in M_n(\mathbb Z[G_D]), invertible over Q[GD]\mathbb Q[G_D] with bounded inverse, whose Fuglede-Kadison determinant lies strictly between 00 and 11; the log integral is finite and negative. The group is nonsofic by Elek-Szabo. It disproves the unrestricted conjecture only; it says nothing about torsion-free groups, groups satisfying the Atiyah conjecture,…

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Theorem 1.1: a finitely generated group GDG_D, n≥1n\ge1 and A∈Mn(Z[GD])A\in M_n(\mathbb Z[G_D]), invertible over Q[GD]\mathbb Q[G_D] with bounded inverse, whose Fuglede-Kadison determinant lies strictly between 00 and 11; the log integral is finite and negative. The group is nonsofic by Elek-Szabo. It disproves the unrestricted conjecture only; it says nothing about torsion-free groups, groups satisfying the Atiyah conjecture, or the determinant approximation conjecture, and it relies on the characteristic-two direct-finiteness counterexample.

Theorem 1.1: a finitely generated group GDG_D, n≥1n\ge1 and A∈Mn(Z[GD])A\in M_n(\mathbb Z[G_D]), invertible over Q[GD]\mathbb Q[G_D] with bounded inverse, whose Fuglede-Kadison determinant lies strictly between 00 and 11; the log integral is finite and negative. The group is nonsofic by Elek-Szabo. It disproves the unrestricted conjecture only; it says nothing about torsion-free groups, groups satisfying the Atiyah conjecture, or the determinant approximation conjecture, and it relies on the characteristic-two direct-finiteness counterexample.

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