let S be non empty satisfying_Tarski-model TarskiGeometryStruct ; for x, y, z, a, b, c, c9, p, q, q9 being POINT of S st not Collinear a,b,c & between b,a,y & a <> y & between a,y,z & y,z equiv y,p & y <> p & q9 = reflection (z,q) & Middle c,x,c9 & c <> y & between q9,y,c9 & Middle y,p,c & between p,y,q & q <> q9 holds
x <> y
let x, y, z, a, b, c, c9, p, q, q9 be POINT of S; ( not Collinear a,b,c & between b,a,y & a <> y & between a,y,z & y,z equiv y,p & y <> p & q9 = reflection (z,q) & Middle c,x,c9 & c <> y & between q9,y,c9 & Middle y,p,c & between p,y,q & q <> q9 implies x <> y )
assume that
A1:
not Collinear a,b,c
and
A2:
between b,a,y
and
A3:
a <> y
and
A4:
between a,y,z
and
A5:
y,z equiv y,p
and
A6:
y <> p
and
A7:
q9 = reflection (z,q)
and
A8:
Middle c,x,c9
and
A9:
c <> y
and
A10:
between q9,y,c9
and
A11:
Middle y,p,c
and
A12:
between p,y,q
and
A13:
q <> q9
; x <> y
assume A14:
x = y
; contradiction
then A15:
Line (a,y) = Line (a,b)
by GTARSKI3:82;
then A16:
Line (y,z) = Line (a,b)
by A15, GTARSKI3:82;
A17:
Line (x,c) = Line (x,c9)
by A8, A9, A14, Prelim10;
Collinear x,c9,q9
by A10, A14, GTARSKI1:def 17;
then A18:
q9 in Line (x,c)
by A17, LemmaA1;
( between c,p,x & between p,x,q & p <> x )
by A14, A6, A11, A12, GTARSKI3:def 12, GTARSKI3:14;
then
between c,x,q
by GTARSKI3:19;
then
Collinear c,x,q
by GTARSKI1:def 17;
then
q in Line (c,x)
by LemmaA1;
then A19:
Line (q,q9) = Line (c,x)
by A13, A9, A14, A18, Prelim11;
Middle q,z,q9
by A7, GTARSKI3:def 13;
then
between q,z,q9
by GTARSKI3:def 12;
then
Collinear q,z,q9
by GTARSKI1:def 17;
then
Collinear q,q9,z
by GTARSKI3:45;
then
z in Line (c,x)
by A19, LemmaA1;
then
Collinear z,c,x
by LemmaA2;
then
Collinear y,z,c
by A14, GTARSKI3:45;
then
c in Line (a,b)
by A16, LemmaA1;
then
Collinear c,a,b
by LemmaA2;
hence
contradiction
by A1, GTARSKI3:45; verum