TOPOLOGY AND ITS APPLICATIONS, vol.301, 2021 (SCI-Expanded)
Menger conjectured that subsets of R with the Menger property must be Sigma-compact. While this is false when there is no restriction on the subsets of R, for projective subsets it is known to follow from the Axiom of Projective Determinacy, which has considerable large cardinal consistency strength. We note that in fact, Menger's conjecture for projective sets has consistency strength of only an inaccessible cardinal. (C) 2020 Elsevier B.V. All rights reserved.