Riemann — is this a proof in four-D space?

(This file keeps the name it was first written under, …2026-09-07, so the paths quoting it elsewhere in the archive stay valid — the same reason the archive folder keeps its own original date. The date above is the date of this version.) The title is a question, put to the reader, because ruling on it is the reader's job. What is set out below is the measurement rung: twelve readings of one edge, each from a different direction, each held out, each with the block and the yardstick it was taken on. The closing step is named at the end, where it belongs. This record holds one paper on its own and is refreshed every couple of months. The complete deposit, 10.5281/zenodo.21788037, holds every paper with its code and data and is updated first; for the newest version of this paper, go there.