The Bass trace conjecture and the characteristic-zero Kaplansky idempotent conjecture

OpenAI

For every torsion-free discrete group G and commutative characteristic-zero domain R, the OpenAI Bass manuscript claims each scalar idempotent in R[G] is 0 or 1. The separate trace-rank assertion concerns algebraic K₀(C[G]).

Sources for this record

What was already known

The scalar idempotent conjecture remained open for general torsion-free groups in characteristic zero. Earlier group-specific and faithful-trace arguments did not give the all-group Bass support theorem used here.

AI involvement AI-led

OpenAI credits its internal model with the mathematical manuscript and Lean development. Earlier faithful-trace methods are human inputs; no named human check or explanation of this corollary is documented.

OpenAI is credited author of the model-produced Bass family; the record does not establish autonomous session conditions.

Importance Major

This settles the characteristic-zero scalar idempotent conjecture for all torsion-free groups.

Limitations

The corollary depends on the complex Bass theorem. Its Lean proof is repository reported; the build and dependencies have not been independently audited. The statement does not cover positive characteristic, reduced C*-algebras or arbitrary matrix idempotents.

Technical verification Formal (Lean)

The released Lean TorsionFree solution states that scalar idempotents over every commutative characteristic-zero domain and torsion-free group are trivial, alongside trace-rank assertions. This relies on the formal Bass trace theorem. The check is repository-reported and not reproduced here.

Formal checking

Lean formalization of torsion_free_corollary and domain_idempotent using the Bass support theorem

Checker
Lean solution module OAI.RingTheory.BassTrace.TorsionFree
Scope
Characteristic-zero scalar idempotents over R G for all torsion-free G and commutative domains R, plus algebraic trace-rank consequences
Basis
Reported by the linked checker
Evidence source

Checking a formal statement does not establish that it matches the original problem.

Human understanding Few

The manuscript gives a derivation, but no named human explanation is documented; Few is the evidence default.

Correction and publication history