On strategy-proofness and semilattice single-peakedness (vol 124, pg 219, 2020)

As was pointed out to us by Huaxia Zeng, Theorem 1 in Bonifacio and Masso (2020), is not correct. In this note we recall former Theorem 1, exhibit a counterexample of its statement, identify the mistake in its faulty proof, and state and prove the new version of Theorem 1. At the end we give an alternative proof of Lemma 9, whose former proof used incorrectly Lemma 5. Notation and definitions are as in the section of Preliminaries in Bonifacio and Masso (2020). (C) 2021 Elsevier Inc. All rights reserved.