let G be non empty right_complementable Abelian add-associative right_zeroed midpoint_operator addLoopStr ; for M being non empty MidStr
for w being Function of [: the carrier of M, the carrier of M:], the carrier of G st w is_atlas_of the carrier of M,G & w is associating holds
M is MidSp
let M be non empty MidStr ; for w being Function of [: the carrier of M, the carrier of M:], the carrier of G st w is_atlas_of the carrier of M,G & w is associating holds
M is MidSp
let w be Function of [: the carrier of M, the carrier of M:], the carrier of G; ( w is_atlas_of the carrier of M,G & w is associating implies M is MidSp )
assume
( w is_atlas_of the carrier of M,G & w is associating )
; M is MidSp
then
for a, b, c, d being Point of M holds
( a @ a = a & a @ b = b @ a & (a @ b) @ (c @ d) = (a @ c) @ (b @ d) & ex x being Point of M st x @ a = b )
by Th1, Th8, Th9, Th19;
hence
M is MidSp
by MIDSP_1:def 3; verum