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5 votes
1 answer
340 views

Thurston universe gates in knots: which invariant is it?

Today I discovered this nice video of a lecture by Thurston: https://youtu.be/daplYX6Oshc in which he explains how a knot can be turned into a "fabric for universes". For example, the unknot ...
Andrea Marino's user avatar
10 votes
0 answers
241 views

What is the preimage of a braid in a covering space branched over the braid?

For a knot $K\subset \mathbb{S}^3$, one can construct the covering space branched over that knot by assigning elements of the symmetric group $S_n$ to each arc of the knot. You can find the knot group ...
cduston's user avatar
  • 145
15 votes
1 answer
778 views

$S^3$ as cyclic branched cover of itself

In Chapter One of his notes (March 2002) Thurston says: If $K$ is the trivial knot the cyclic branched covers are $S^3$. It seems intuitively obvious (but it is not known) that this is the only ...
Antonio Alfieri's user avatar
5 votes
3 answers
1k views

Heegaard Floer Homology of double branched cover

The question is the following: Let $K\subset S^{3}$ be a knot, consider the double branched cover $Y$ of $S^{3}$ over $K$. We know $Y$ has a unique spin structure $\mathfrak{s}$, now the question is: ...
user44651's user avatar
  • 1,059
5 votes
1 answer
1k views

The cyclic branched covers of "simple" knots in $S^3$

Is there a convenient place in the literature where the geometric decompositions of cyclic branched covers of $S^3$ branched over "small" knots is recorded? By small knots, I'm referring to things ...
Ryan Budney's user avatar
  • 43.5k