Preliminary public record of an explicit strongly connected counterexample to the same-function product-preservation question for f-corners. The record includes the manuscript, Lean 4 certificates, independent Python replay and enumeration scripts, deterministic receipts, and SHA-256 manifests. It has not been peer reviewed or endorsed. The public timestamp records the deposited bytes; it does not by itself establish mathematical correctness, novelty, or priority.
xiao et al. (Sat,) studied this question.