theorem Th1: :: PROJDES1:1

for FCPS being up-3-dimensional CollProjectiveSpace
for a, b, c being Element of FCPS st a,b,c are_collinear holds
( b,c,a are_collinear & c,a,b are_collinear & b,a,c are_collinear & a,c,b are_collinear & c,b,a are_collinear )