Let F be a Bedford–McMullen carpet defined by independent exponents. We prove that dim¯Bfalse(ℓ∩Ffalse)⩽maxfalse{dim∗F−1,0false} for all lines ℓ not parallel to the principal axes, where dim∗ is Furstenberg's star dimension (maximal dimension of a microset). We also prove several rigidity results for incommensurable Bedford–McMullen carpets, that is, carpets F and E such that all defining exponents are independent: Assuming various conditions, we find bounds on the dimension of the intersection of such carpets, show that self‐affine measures on them are mutually singular, and prove that they do not embed affinely into each other.
We obtain these results as an application of a slicing theorem for products of certain Cantor sets. This theorem is a generalization of the results of Shmerkin [Ann. of Math. (2) 189 (2019) 319–391] and Wu [Ann. of Math. (2) 189 (2019) 707–751], which proved Furstenberg's slicing conjecture [Problems in analysis (ed. R. C. Gunning; Princeton University Press, Princeton, NJ, 1970) 41–59].