[#P3086] An explicit exponential lower bound for diagonal Ramsey numbers
Problem. Give a deterministic, explicit construction which, for infinitely many integers \(k\), produces a red-blue edge-colouring of \(K_{N_k}\) with no monochromatic \(K_k\), where \(N_k\ge C^k\) for one absolute constant \(C>1\).
1Context
Known frontier: The maintained record gives explicit constructions whose largest clique or independent set is at most \((\log n)^C\), which remains too large to yield \(N_k\ge C_0^k\). Open boundary: Obtain any fixed exponential base greater than one by an explicit construction.
2Problem setup
Definition 1 (Explicit construction). A deterministic finite description or algorithm outputs the colouring from \(k\), with correctness proved without selecting a favourable random outcome.
Definition 2 (Ramsey-avoiding colouring). Neither colour class contains a complete graph on \(k\) vertices.
Remark 1. The probabilistic method gives a stronger existential size, while known explicit constructions remain subexponential in the required sense.
3What counts as a solution
- Specify the construction, prove it avoids monochromatic \(K_k\), and prove \(N_k\ge C^k\) for a fixed \(C>1\) on an infinite sequence of \(k\).
1Status
Current status (Current status and exact unresolved remainder). OPEN as checked on 2026-08-01. Strongest checked neighboring result: The maintained record gives explicit constructions whose largest clique or independent set is at most \((\log n)^C\), which remains too large to yield \(N_k\ge C_0^k\). Exact unresolved remainder: Obtain any fixed exponential base greater than one by an explicit construction.[1][2]
1Records
Notes and companion material
Original intake status. OPEN as checked on 2026-08-01. Strongest checked neighboring result: The maintained record gives explicit constructions whose largest clique or independent set is at most \((\log n)^C\), which remains too large to yield \(N_k\ge C_0^k\). Exact unresolved remainder: Obtain any fixed exponential base greater than one by an explicit construction.
- Equivalent-formulation queries: "Erdős Problem #78" constructive Ramsey; explicit construction R(k) > C^k; explicit Ramsey graph logarithmic clique independent set 2025 2026
- Strongest checked neighboring result: The maintained record gives explicit constructions whose largest clique or independent set is at most \((\log n)^C\), which remains too large to yield \(N_k\ge C_0^k\).
- Exact unresolved remainder: Obtain any fixed exponential base greater than one by an explicit construction.
How the 4 records connect
ProblemAn explicit exponential lower bound for diagonal Ramsey numbers
2See also
- Cycle Double Cover Conjecturegraph theory
- Is there a truly subcubic algorithm for weighted APSP?graph theory
- The Total Coloring Conjecturegraph theory
How to cite
TheoremDB contributors, “An explicit exponential lower bound for diagonal Ramsey numbers,” TheoremDB research memory, snapshot of August 1, 2026. https://theoremdb.org/statements/constructive-exponential-ramsey-lower-boundThis page as plain text: constructive-exponential-ramsey-lower-bound.md
This problem includes 4 records joined by 3 typed links, sourced from erdosproblems.com[1], current as of August 1, 2026.
1References
- Packet source. Thomas F. Bloom, Erdős Problem #78, Erdős Problems database (living entry), accessed 2026-08-01. Problem #78, OPEN banner, statement, remarks, and bibliography. Problem #78, OPEN banner, statement, remarks, and bibliography. ↗reference database · reference source · checked 2026-08-01Source use: original summary.Supplies the maintained formulation, current open-status assessment, and recorded partial results.Also cited at Thomas F. Bloom, Erdős Problem #78, Erdős Problems database (living entry), accessed 2026-08-01. Problem #78, OPEN banner, statement, remarks, and bibliography.Source used to assess the problem's recorded status.For An explicit exponential lower bound for diagonal Ramsey numbers: This is the dated publication status for the canonical target An explicit exponential lower bound for diagonal Ramsey numbers.Source named by the research packet.
- Paul Erdős, “Some unsolved problems,” Magyar Tud. Akad. Mat. Kutató Int. Közl. 6 (1961), 221–254. Probabilistic Ramsey lower bounds and explicit-construction question. ↗journal article · primary source · checked 2026-08-01Source use: original summary.Records an original formulation or early published statement of the problem.Source used to assess the problem's recorded status.For An explicit exponential lower bound for diagonal Ramsey numbers: Records an original formulation or early published statement of the problem.
Original TheoremDB statement and summary based on citation-only scholarly sources; no source prose, proof, table, code, or figure is reproduced.