Definition Qmean_property_l x y (hyp:x<y) := proj1 (Qmean_property x y hyp).Definition Qmean_property_r x y (hyp:x<y) := proj2 (Qmean_property x y hyp).

Lemma Qmean_incr: forall x1 x2 y1 y2, x1< x2 -> y1 < y2 -> Qmean x1 y1 < Qmean x2 y2.