analysis / Operator algebras; nuclear dimension of nonsimple C*-algebras

Robert-Tikuisis Conjecture (C1): finite nuclear dimension implies Jiang-Su stability without elementary subquotients

Theorem 1.1: for separable nuclear AA with no nonzero elementary ideal subquotients, dim⁡nucA<∞\dim_{nuc}A<\infty, A≅A⊗ZA\cong A\otimes\mathcal Z and dim⁡nucA≤1\dim_{nuc}A\le1 are equivalent. Theorem 1.3: dim⁡nuc(A0⊗Z)≤1\dim_{nuc}(A_0\otimes\mathcal Z)\le1 for every separable nuclear A0A_0. Theorem 1.4 answers Kirchberg-Rordam's Question 6.2 (full orthogonal positive elements in a finite maximal tensor power of a unital algebra without characters). It does not address the strict-comparison part of the nonsimple problem, which the Cuntz-comparison companion treats.

25Significance / 100
1Frontier events
0Verification tasks
0Recorded attempts

Temporal state

Current frontier

No reconciled state yet.

Append-only history

Frontier timeline

analysisSep 23, 2026Significance 25/100Registry: unreviewed

Robert-Tikuisis Conjecture (C1): finite nuclear dimension implies Jiang-Su stability without elementary subquotients

Prior state unknown→proved

Theorem 1.1: for separable nuclear AA with no nonzero elementary ideal subquotients, dim⁡nucA<∞\dim_{nuc}A<\infty, A≅A⊗ZA\cong A\otimes\mathcal Z and dim⁡nucA≤1\dim_{nuc}A\le1 are equivalent. Theorem 1.3: dim⁡nuc(A0⊗Z)≤1\dim_{nuc}(A_0\otimes\mathcal Z)\le1 for every separable nuclear A0A_0. Theorem 1.4 answers Kirchberg-Rordam's Question 6.2 (full orthogonal positive elements in a finite maximal tensor power of a unital algebra without characters…

SourceReplayReproducedFormal proofStatement auditExternal checkExpert reviewPeer review

Research memory

Claims and attempts

Scoped claims

Source authenticated

Theorem 1.1: for separable nuclear AA with no nonzero elementary ideal subquotients, dim⁡nucA<∞\dim_{nuc}A<\infty, A≅A⊗ZA\cong A\otimes\mathcal Z and dim⁡nucA≤1\dim_{nuc}A\le1 are equivalent. Theorem 1.3: dim⁡nuc(A0⊗Z)≤1\dim_{nuc}(A_0\otimes\mathcal Z)\le1 for every separable nuclear A0A_0. Theorem 1.4 answers Kirchberg-Rordam's Question 6.2 (full orthogonal positive elements in a finite maximal tensor power of a unital algebra without characters). It does not address the strict-comparison part of the nonsimple problem, which the Cuntz-comparison companion treats.

Theorem 1.1: for separable nuclear AA with no nonzero elementary ideal subquotients, dim⁡nucA<∞\dim_{nuc}A<\infty, A≅A⊗ZA\cong A\otimes\mathcal Z and dim⁡nucA≤1\dim_{nuc}A\le1 are equivalent. Theorem 1.3: dim⁡nuc(A0⊗Z)≤1\dim_{nuc}(A_0\otimes\mathcal Z)\le1 for every separable nuclear A0A_0. Theorem 1.4 answers Kirchberg-Rordam's Question 6.2 (full orthogonal positive elements in a finite maximal tensor power of a unital algebra without characters). It does not address the strict-comparison part of the nonsimple problem, which the Cuntz-comparison companion treats.

Recorded attempts

Evidence graph

Connected research record