Second autocorrelation inequality: lower bound on the constant C2

The best constant C2 in ‖f⋆f‖₂² ≤ C2 ‖f⋆f‖₁ ‖f⋆f‖∞ for f ≥ 0. A discretised function gives the lower bound ‖f⋆f‖₂² / (‖f⋆f‖₁ ‖f⋆f‖∞); larger is better (the trivial maximum is 1).

Scores of discretised functions (up to 4×10^5 intervals), in floating point: numerical bounds. Outside the platform, ImprovEvolve (arXiv 2602.10233) reports 0.96258 without releasing the solution; the paper keeps 0.9610 as the prior record. Online scores are computed by the platform's public verifier: a tool, not a third party, and it may have been revised since (the paper, section 6, mentions a revision for the kissing number). No named reviewer.