I have read in different places, that for $n\leq 4$, PL and Diff are equivalent (passing through PDIFF). I believe Milnor gave an example of the inequivalence for $n=7$. What about for $n=5$ or $n=6$? Are there examples of PL manifolds which are not smoothable?
2026-03-29 11:07:04.1774782424
In what dimensions are PL and Diff equivalent?
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A more qeneral question is References on the relations between Top, Diff and PL. It gives a reference to https://mathoverflow.net/q/96670 which gives a complete (positive) answer for $n =5, 6$.