A simple closed curve on a sphere that is not necessarily a great circle but merely intersects as a great circle would (Billera et al. 1999).
Pseudocircle
See also
Great CircleExplore with Wolfram|Alpha
References
Billera, L. J.; Brown, K. S.; and Diaconis, P. "Random Walks and Plane Arrangements in Three Dimensions." Amer. Math. Monthly 106, 502-524, 1999.Björner, A; Las Vargnas, M.; Sturmfels, B.; White, N.; and Ziegler, G. M. Oriented Matroids, 2nd ed. Cambridge, England: Cambridge University Press, 2000.Grünbaum, B. Arrangements and Spreads. Providence, RI: Amer. Math. Soc., 1972.Ziegler, G. M. Lectures on Polytopes. New York: Springer-Verlag, 1995.Referenced on Wolfram|Alpha
PseudocircleCite this as:
Weisstein, Eric W. "Pseudocircle." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Pseudocircle.html