combinatorics / Arithmetic Ramsey Theory

Erdős Problem #1186

What is the minimum asymptotic density $\delta_k$ of monochromatic $k$-term arithmetic progressions in every two-colouring of $\{1, \dots, n\}$? The exact certificate gives $\delta_3 = 117/2192$, matching the known 548-bead colouring.

10Significance / 100
1Frontier events
0Verification tasks
0Recorded attempts

Temporal state

Current frontier

No reconciled state yet.

Append-only history

Frontier timeline

combinatoricsJul 13, 2026Significance 10/100Registry: unreviewed

Erdős Problem #1186

Prior state unknownproved

exact k = 3 constant established, settling the Parrilo-Robertson-Saracino conjecture for 3-APs; general k remains open

SourceReplayReproducedFormal proofStatement auditExternal checkExpert reviewPeer review

Research memory

Claims and attempts

Scoped claims

Source authenticated

What is the minimum asymptotic density $\delta_k$ of monochromatic $k$-term arithmetic progressions in every two-colouring of $\{1, \dots, n\}$? The exact certificate gives $\delta_3 = 117/2192$, matching the known 548-bead colouring.

exact k = 3 constant established, settling the Parrilo-Robertson-Saracino conjecture for 3-APs; general k remains open

Recorded attempts

Evidence graph

Connected research record

No public relationships recorded yet.