The intersection 
of all maximal subgroups of a given group 
.
Frattini Subgroup
See also
Frattini Extension, Frattini FactorExplore with Wolfram|Alpha
References
Besche, H.-U. and Eick, B. "Construction of Finite Groups." J. Symb. Comput. 27, 387-404, 1999.Gaschütz, W. "Über
-Untergruppen
endlicher Gruppen." Math. Z. 58, 160-170, 1953.Referenced on Wolfram|Alpha
Frattini SubgroupCite this as:
Weisstein, Eric W. "Frattini Subgroup." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/FrattiniSubgroup.html