Capacity-Neutral Deviations in Sweep-Based Service: A Geometry-Mediated Channel of Strategic Complementarity

Working paper with the complete code that produced it. In a down-peak elevator system, a passenger who wants to descend may instead board an ascending car, ride to the car's reversal floor, and come back down. The passenger occupies one seat — exactly as a compliant passenger would — so the deviation consumes no additional physical capacity. Yet it changes the order in which floors are served and raises the car's reversal floor H, lengthening the round trip and shrinking the number of service slots the system delivers per unit time. The paper derives this channel and tests it by suppressing it: replaying the reversal-floor trajectory observed under full compliance blocks the p → H → RTT pathway while leaving the rest of the system intact. Under this suppression the strategic response reverses sign on the floors where the deviation is actually chosen (+130 → −33 and +100 → −82 seconds per unit adoption; reversal in 9 of 10 and 10 of 10 random seeds). There is no field data. This is theory plus computational experiment. The simulator is validated against published lift-traffic values to within 0.3%. Every figure is regenerated from stored result files by a single script. The repository also keeps the research record, including hypotheses that were tested and rejected — among them the author's original mechanism, which the simulation falsified. AI assistance. This work was produced with AI assistance. The author set the research question, the empirical constraints and the standard of evidence, and reviewed and accepted every result; the literature search, model, simulation code, experiments and first drafts were produced by an AI coding agent working under that direction, with separate agent instances used as adversarial auditors. Responsibility for the content rests with the author.