Section MinMaxGroup.
Variable gT : finGroupType.
Implicit Types gP : pred {group gT}.
Definition maxgroup A gP := maxset (fun A => group_set A && gP <<A>>%G) A.
Definition mingroup A gP := minset (fun A => group_set A && gP <<A>>%G) A.
Variable gP : pred {group gT}.
Arguments gP _%G.

Lemma ex_maxgroup : (exists G, gP G) -> {G : {group gT} | maxgroup G gP}.