let AP be AffinPlane; ( AP is Moufangian implies AP is satisfying_TDES_1 )
assume A1:
AP is Moufangian
; AP is satisfying_TDES_1
let K be Subset of AP; AFF_2:def 8 for o, a, b, c, a9, b9, c9 being Element of AP st K is being_line & o in K & c in K & c9 in K & not a in K & o <> c & a <> b & LIN o,a,a9 & a,b // a9,b9 & b,c // b9,c9 & a,c // a9,c9 & a,b // K holds
LIN o,b,b9
let o, a, b, c, a9, b9, c9 be Element of AP; ( K is being_line & o in K & c in K & c9 in K & not a in K & o <> c & a <> b & LIN o,a,a9 & a,b // a9,b9 & b,c // b9,c9 & a,c // a9,c9 & a,b // K implies LIN o,b,b9 )
assume that
A2:
K is being_line
and
A3:
o in K
and
A4:
c in K
and
A5:
c9 in K
and
A6:
not a in K
and
A7:
o <> c
and
A8:
a <> b
and
A9:
LIN o,a,a9
and
A10:
a,b // a9,b9
and
A11:
b,c // b9,c9
and
A12:
a,c // a9,c9
and
A13:
a,b // K
; LIN o,b,b9
consider P being Subset of AP such that
A14:
a9 in P
and
A15:
K // P
by A2, AFF_1:49;
A16:
P is being_line
by A15, AFF_1:36;
set A = Line (o,b);
set C = Line (o,a);
A17:
( o in Line (o,b) & b in Line (o,b) )
by AFF_1:15;
assume A18:
not LIN o,b,b9
; contradiction
then
o <> b
by AFF_1:7;
then A19:
Line (o,b) is being_line
by AFF_1:def 3;
A20:
not b in K
by A6, A13, AFF_1:35;
not Line (o,b) // P
then consider x being Element of AP such that
A21:
x in Line (o,b)
and
A22:
x in P
by A19, A16, AFF_1:58;
A23:
( o in Line (o,a) & a in Line (o,a) )
by AFF_1:15;
A24:
LIN o,b,x
by A19, A17, A21, AFF_1:21;
a,b // P
by A13, A15, AFF_1:43;
then
a9,b9 // P
by A8, A10, AFF_1:32;
then A25:
b9 in P
by A14, A16, AFF_1:23;
then A26:
LIN b9,x,b9
by A16, A22, AFF_1:21;
A27:
Line (o,a) is being_line
by A3, A6, AFF_1:def 3;
then A28:
a9 in Line (o,a)
by A3, A6, A9, A23, AFF_1:25;
A29:
b9 <> c9
proof
A30:
a9,
c9 // c,
a
by A12, AFF_1:4;
assume A31:
b9 = c9
;
contradiction
then
P = K
by A5, A15, A25, AFF_1:45;
then
a9 = o
by A2, A3, A6, A27, A23, A28, A14, AFF_1:18;
then
b9 = o
by A2, A3, A4, A5, A6, A31, A30, AFF_1:48;
hence
contradiction
by A18, AFF_1:7;
verum
end;
A32:
b <> c
by A4, A6, A13, AFF_1:35;
a9,x // K
by A14, A15, A22, AFF_1:40;
then
a,b // a9,x
by A2, A13, AFF_1:31;
then
b,c // x,c9
by A1, A2, A3, A4, A5, A6, A7, A8, A9, A12, A13, A24;
then
b9,c9 // x,c9
by A11, A32, AFF_1:5;
then
c9,b9 // c9,x
by AFF_1:4;
then
LIN c9,b9,x
by AFF_1:def 1;
then A33:
LIN b9,x,c9
by AFF_1:6;
A34:
a9 <> b9
proof
assume A35:
a9 = b9
;
contradiction
(
a,
c // b,
c or
a9 = c9 )
by A11, A12, A35, AFF_1:5;
then
c,
a // c,
b
by A36, AFF_1:4;
then
LIN c,
a,
b
by AFF_1:def 1;
then
LIN a,
c,
b
by AFF_1:6;
then
a,
c // a,
b
by AFF_1:def 1;
then
a,
b // a,
c
by AFF_1:4;
then
a,
c // K
by A8, A13, AFF_1:32;
then
c,
a // K
by AFF_1:34;
hence
contradiction
by A2, A4, A6, AFF_1:23;
verum
end;
LIN b9,x,a9
by A14, A16, A22, A25, AFF_1:21;
then
LIN b9,c9,a9
by A18, A24, A33, A26, AFF_1:8;
then
b9,c9 // b9,a9
by AFF_1:def 1;
then
b9,c9 // a9,b9
by AFF_1:4;
then
b,c // a9,b9
by A11, A29, AFF_1:5;
then
a,b // b,c
by A10, A34, AFF_1:5;
then
b,c // K
by A8, A13, AFF_1:32;
then
c,b // K
by AFF_1:34;
hence
contradiction
by A2, A4, A20, AFF_1:23; verum