The signature s(K) of a knot K can be defined using the skein relationship s(unknot) = 0 s(K_+) - s(K_-) element {0, 2}, and 4|s(K)<-> del (K)(2i)>0, where del (K) is the Conway polynomial and del (K)(2i) is an odd number. Many unknotting numbers can be determined using a knot's signature. Knot signatures are implemented in the Wolfram Language as KnotData[knot, Signature]. The following table summarizes knot signatures for knots on 10 of fewer crossings.

skein relationship | unknotting number