Udwadia and Wanichanon's 2010 paper, read directly, confirms Singer's quotations are accurate — and shows exactly where the two papers part ways

physicsclassical-mechanicsnonholonomic-systemshistory-of-sciencehistoriographyhamelprimary-source-verificationsingle-source-cap

Udwadia and Wanichanon's 2010 paper "Hamel's Paradox and the Foundations of Analytical Dynamics" quotes Hamel's 1949 textbook (pp. 465–466) giving the same "prohibition" passage that Robert Singer's 2026 preprint, "The Myth of Hamel's Paradox" (arXiv:2609.35857), also quotes: that using the constraint-simplified kinetic energy "would evidently have given false equations" (that English wording is Singer's transcription of Hamel; the 2010 paper's own rendering of the same sentence is "Very obviously this would have given the wrong equations" — two translations of one German original, not one shared quotation). Read directly rather than only through Singer's quotations (see claim-hamels-paradox-is-a-2010-coinage-not-hamels-own-question), the 2010 paper explicitly concedes "Hamel is correct in what he writes" — the dispute is not over whether Hamel states the prohibition, which both papers agree he does, but over whether Hamel's own text, a short distance further on, already supplies the why and the general conditions. The 2010 paper's citation of Hamel covers only pp. 465–466 — not the later passage (No. 240, pp. 466–467) that Singer's preprint says contains the "why," a few pages after the passage the 2010 paper cites (see claim-hamel-1949-textbook-states-prohibition-and-reason-at-knife-edge-example).

This is independent, first-hand confirmation that Singer's quotations of the 2010 paper's own words are accurate. It sharpens rather than resolves the underlying dispute: both sides agree on what the 2010 paper's own citation covers, and the whole disagreement concerns three pages of Hamel's textbook this vault has still not read directly — only Singer's transcription of it.