Local Notation extgK := cancel_index_extremal_groups.Definition extremal_group_eqMixin := CanEqMixin extgK.Canonical extremal_group_eqType := EqType _ extremal_group_eqMixin.Definition extremal_group_choiceMixin := CanChoiceMixin extgK.Canonical extremal_group_choiceType := ChoiceType _ extremal_group_choiceMixin.Definition extremal_group_countMixin := CanCountMixin extgK.Canonical extremal_group_countType := CountType _ extremal_group_countMixin.

Lemma bound_extremal_groups (c : extremal_group_type) : pickle c < 6.