A projective correlation of period two. In a polarity, 
is called the polar of 
, and 
the inversion pole 
.
Polarity
See also
Chasles's Theorem, Geometric Correlation, Inversion Pole, Lattice Polarity, Polar, Projective CorrelationExplore with Wolfram|Alpha
References
Coxeter, H. S. M. Introduction to Geometry, 2nd ed. New York: Wiley, p. 248, 1969.Referenced on Wolfram|Alpha
PolarityCite this as:
Weisstein, Eric W. "Polarity." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Polarity.html