Essay on the Poincaré Conjecture
I wrote this essay in 2007 for publication in an Italian encyclopedia
of mathematical problems. At this time it was still not 100% certain
that Perelman's proof of the 3-dimensional conjecture was correct and
this is why I have been a little tentative about his proof. If
writing now I would change the title of section 7 from "Perelman's
program" to "Perelman's proof". Nothing else needs updating.
Essay on the Poincaré conjecture