A correction note on normalization and auxiliary estimates in Sharp volume bounds for BRK-type sets of surfaces of revolution

This independent correction note examines auxiliary assertions in Xianghong Chen and Tongou Yang, “Sharp volume bounds for BRK-type sets of surfaces of revolution,” arXiv:2609.39059v1 (30 September 2026). A family of shrinking spheres satisfies a common neighborhood-intersection bound but contradicts the uniform operator-constant dependence declared in Lemma 1.11. Explicit normalized L1-to-Linfinity and L2-to-L2 endpoint bounds are supplied with proofs. The exponential tangency example in Remark 1.2 is incompatible with the prescribed radial interval, and its printed neighborhood-volume exponent is incorrect. A corrected compact-patch example has overlap comparable to delta^(3/2). Parameter-dependent additive constants contradict the full C1-norm estimates in Propositions 2.2 and 3.1. An explicit normalization supplies the missing zeroth-order bound and preserves the relevant level sets exactly. A local sign correction in equation (5.12) is also recorded. These conclusions concern the printed auxiliary assertions in version 1. They do not disprove the principal sphere-packing theorem or certify the original paper’s entire proof. The endpoint lemma does not claim a proof of the complete sharp Lp-Lq range. The record contains the revised manuscript PDF and its complete LaTeX source archive.