Knot invariant
From Topospaces
This term is related to: knot theory
Definition
A knot invariant is a function from the set of all knots (embeddings of 
in 
) to some set, which is invariant under isotopy; in other words, if there is a self-homeomorphism of , isotopic to the identity map, which sends one knot to the other, then the function should take the same value on both knots.
Note that isotopy-invariance is a weaker condition than being invariant under self-homeomorphisms, because the sphere possesses an orientation-reversing self-homeomorphism.
A list of knot invariants can be found at:
