let PCPP be CollProjectiveSpace; for p being Element of PCPP holds
not for q, r being Element of PCPP holds p,q,r is_collinear
let p be Element of PCPP; not for q, r being Element of PCPP holds p,q,r is_collinear
consider q being Element of PCPP such that
A1:
p <> q
and
p <> q
and
p,p,q is_collinear
by ANPROJ_2:def 10;
not for r being Element of PCPP holds p,q,r is_collinear
by A1, Th6;
hence
not for q, r being Element of PCPP holds p,q,r is_collinear
; verum