On clique-to-clique densities
Pith reviewed 2026-07-01 04:18 UTC · model grok-4.3
The pith
For any s less than t the t-clique density is at least the Lovász–Simonovits t-function applied to the inverse of the s-function of the given s-clique density.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
For any integers 2 ≤ s < t the inequality k_t(G)/n^t ≥ F_t(F_s^{-1}(k_s(G)/n^s)) holds in every n-vertex graph G, where F_r denotes the Lovász–Simonovits r-clique density function and F_s^{-1} its generalized inverse; the bound is asymptotically sharp.
What carries the argument
The composition F_t ∘ F_s^{-1} of the Lovász–Simonovits r-clique density functions with the generalized inverse of the s-function, which produces the minimal possible t-clique density consistent with a prescribed s-clique density.
If this is right
- The bound is asymptotically sharp.
- It strengthens Bollobás's piecewise-linear interpolation bound.
- When s equals 2 the inequality recovers Reiher's clique density theorem.
- The proof for the s=2 case is inductive.
Where Pith is reading between the lines
- The same composition technique might produce bounds that relate densities of three or more different clique sizes at once.
- The inductive argument could be adapted to obtain similar relations for other uniform hypergraph densities.
- Explicit computation of the functions F_r for small r would turn the bound into concrete numerical inequalities for concrete pairs s and t.
Load-bearing premise
The Lovász–Simonovits functions admit generalized inverses whose composition yields exactly the smallest t-clique density that can occur with a given s-clique density in the large-n limit.
What would settle it
A sequence of graphs on n vertices whose t-clique count divided by n^t falls below F_t(F_s^{-1}(k_s(G)/n^s)) by a positive fraction that does not tend to zero.
read the original abstract
Let $k_r(G)$ denote the number of $r$-cliques in a graph $G$ and let $F_r(\cdot)$ be the Lov\'asz--Simonovits $r$-clique density function. For any integers $2\le s<t$, we determine the asymptotically sharp lower bound on $k_t(G)$ in an $n$-vertex graph $G$ with a prescribed number $k_s(G)$, by showing that \[ \frac{k_t(G)}{n^t}\ge F_t\!\left(F_s^{-1}\!\left(\frac{k_s(G)}{n^s}\right)\right), \] where $F_s^{-1}$ denotes the generalized inverse. This strengthens Bollob\'as's piecewise-linear interpolation bound and, in the case $s=2$, recovers Reiher's clique density theorem via a new inductive proof.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript proves that for integers 2 ≤ s < t, any n-vertex graph G satisfies k_t(G)/n^t ≥ F_t(F_s^{-1}(k_s(G)/n^s)), where F_r is the Lovász–Simonovits r-clique density function and F_s^{-1} its generalized inverse. The bound is asymptotically sharp, strengthens Bollobás's piecewise-linear interpolation, and recovers Reiher's theorem for s=2 via a new inductive proof that reduces the general case to the known s=2 result while verifying the required monotonicity and continuity properties of the F_r.
Significance. If the inductive argument holds, the result determines the exact asymptotic extremal function for t-clique densities given s-clique densities by direct composition of established Lovász–Simonovits functions, with no free parameters or ad-hoc constructions. The reduction to Reiher's theorem together with the explicit verification that the generalized inverses are well-defined and attain the infimum constitutes a clean advance in extremal graph theory.
Simulated Author's Rebuttal
We thank the referee for their positive summary of the manuscript and for recommending acceptance. No major comments were provided in the report.
Circularity Check
No significant circularity in the derivation chain
full rationale
The central inequality is obtained by composing the externally established Lovász–Simonovits functions F_r (defined independently of this paper) with their generalized inverses. The manuscript supplies an inductive argument that reduces the (s,t) case to the known s=2 case of Reiher and verifies the required monotonicity and continuity properties of F_r needed for the inverse to be well-defined. These steps rely on prior external results rather than self-referential definitions, fitted parameters renamed as predictions, or load-bearing self-citations. The derivation is therefore self-contained against external benchmarks.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption The Lovász–Simonovits r-clique density functions F_r are continuous, non-decreasing, and admit generalized inverses that correctly capture the extremal densities.
Forward citations
Cited by 1 Pith paper
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An edge-spectral supersaturation of Mubayi's theorem for color-critical graphs
For color-critical F with χ(F)=r+1≥4, λ²(G) ≥ 2(1-1/r)m + q implies N_F(G) ≥ (B_F - o(1)) q m^{(f-2)/2} for small q, with sharp B_F = α_F/4 ⋅ (2r/(r-1))^{f/2}.
Reference graph
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