This record contains a preprint manuscript presenting a proof of Erdős Problem 887. The manuscript proves an eventual four-divisor bound for the fourth-root near-root divisor window. For each fixed constant C > 0, it proves that there is a threshold N (C) such that the interval (sqrt (n), sqrt (n) + C n^ (1/4) ) contains at most four divisors of n for all n >= N (C). The proof is organized around two reductions. The external reconstruction reduction turns an unbounded sequence of five-divisor violations into a normalized legal five-endpoint K5 survivor carrying a canonical interval-overload datum. The internal obstruction proves that no such canonical interval-overload datum exists. A companion Lean 4 formalization is archived separately and mirrors the theorem-source architecture of the manuscript.
Jarek Koch (Fri,) studied this question.