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added the s-invariant to the list, improved formatting
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Marco Golla
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A "classic" wayThere are several ways to do this is using the signature; another way is computing Jones polynomial; a third way is using Heegaard Floer homology,try and the $\tau$-invarianttell apart a knot from its mirror

  • Probably the most "classic" way to do this is using the signature;

  • You can compute Jones polynomial and check that it's not symmetric;

  • You can use Rasmussen's $s$-invariant coming from Khovanov homology;

  • You can use Heegaard Floer homology, and the $\tau$-invariant of Ozsváth and Szabó.

Each of Ozsváth and Szabó: they are allthe invariants above is often sensitive to orientation reversal in many cases.

Forreversal; for example, all threefour invariants tell apart the left-handed trefoil from the right-handed trefoil.

If you want to show that a knot is amphicheiral (i.e. isotopic to its mirror image), you have to fiddle around with diagrams and Reidemeister moves.

As far as I know, there is no general way of doing itcriterion to answer your question, though.

A "classic" way to do this is using the signature; another way is computing Jones polynomial; a third way is using Heegaard Floer homology, and the $\tau$-invariant of Ozsváth and Szabó: they are all sensitive to orientation reversal in many cases.

For example, all three invariants tell apart the left-handed trefoil from the right-handed trefoil.

If you want to show that a knot is amphicheiral (i.e. isotopic to its mirror image), you have to fiddle around with diagrams and Reidemeister moves.

As far as I know, there is no general way of doing it, though.

There are several ways to try and tell apart a knot from its mirror

  • Probably the most "classic" way to do this is using the signature;

  • You can compute Jones polynomial and check that it's not symmetric;

  • You can use Rasmussen's $s$-invariant coming from Khovanov homology;

  • You can use Heegaard Floer homology, and the $\tau$-invariant of Ozsváth and Szabó.

Each of the invariants above is often sensitive to orientation reversal; for example, all four invariants tell apart the left-handed trefoil from the right-handed trefoil.

If you want to show that a knot is amphicheiral (i.e. isotopic to its mirror image), you have to fiddle around with diagrams and Reidemeister moves.

As far as I know, there is no general criterion to answer your question, though.

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Marco Golla
  • 10.9k
  • 3
  • 41
  • 63

A "classic" way to do this is using the signature; another way is computing Jones polynomial; a third way is using Heegaard Floer homology, and the $\tau$-invariant of Ozsváth and Szabó: they are all sensitive to orientation reversal in many cases.

For example, all three invariants tell apart the left-handed trefoil from the right-handed trefoil.

If you want to show that a knot is amphicheiral (i.e. isotopic to its mirror image), you have to fiddle around with diagrams and Reidemeister moves.

As far as I know, there is no general way of doing it, though.