for SAS being Semi_Affine_Space
for a1, a2, a3, a4 being Element of SAS st parallelogram a1,a2,a3,a4 holds
( not a1,a2,a3 are_collinear & not a1,a3,a2 are_collinear & not a1,a2,a4 are_collinear & not a1,a4,a2 are_collinear & not a1,a3,a4 are_collinear & not a1,a4,a3 are_collinear & not a2,a1,a3 are_collinear & not a2,a3,a1 are_collinear & not a2,a1,a4 are_collinear & not a2,a4,a1 are_collinear & not a2,a3,a4 are_collinear & not a2,a4,a3 are_collinear & not a3,a1,a2 are_collinear & not a3,a2,a1 are_collinear & not a3,a1,a4 are_collinear & not a3,a4,a1 are_collinear & not a3,a2,a4 are_collinear & not a3,a4,a2 are_collinear & not a4,a1,a2 are_collinear & not a4,a2,a1 are_collinear & not a4,a1,a3 are_collinear & not a4,a3,a1 are_collinear & not a4,a2,a3 are_collinear & not a4,a3,a2 are_collinear )