Let a knot be -embeddable. Then its tunnel number is a knot invariant which is related to .
Tunnel Number
See also
Embeddable KnotExplore with Wolfram|Alpha
References
Adams, C. C. The Knot Book: An Elementary Introduction to the Mathematical Theory of Knots. New York: W. H. Freeman, p. 114, 1994.Referenced on Wolfram|Alpha
Tunnel NumberCite this as:
Weisstein, Eric W. "Tunnel Number." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/TunnelNumber.html