Geometrically Essential
A disk D in a solid torus V=S^1×D^2 is called meridinal if its boundary is a nontrivial curve in del V (so that it is a meridian). Then a closed subset X subset V is called geometrically essential in V if X intersects every piecewise linear meridinal disk in V (Rolfsen 1976, p. 110).
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References
Rolfsen, D. Knots and Links. Wilmington, DE: Publish or Perish Press, 1976.Referenced on Wolfram|Alpha
Geometrically EssentialCite this as:
Weisstein, Eric W. "Geometrically Essential." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/GeometricallyEssential.html