The Pappus configuration is the 
configuration illustrated
above that appears in Pappus's hexagon theorem.
It is one of the three 
configurations.
The Levi graph of the Pappus configuration is known as the Pappus graph.
Pappus Configuration
See also
Pappus Graph, Pappus's Hexagon TheoremExplore with Wolfram|Alpha
References
Coxeter, H. S. M. "Self-Dual Configurations and Regular Graphs." Bull. Amer. Math. Soc. 56, 413-455, 1950.Grünbaum, B. Configurations of Points and Lines. Providence, RI: Amer. Math. Soc., pp. 1-2 and 9, 2009.Referenced on Wolfram|Alpha
Pappus ConfigurationCite this as:
Weisstein, Eric W. "Pappus Configuration." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/PappusConfiguration.html