let X be OrtAfPl; ( Af X is translational implies X is satisfying_des )
assume A1:
Af X is translational
; X is satisfying_des
let a be Element of ; CONMETR:def 8 for a1, b, b1, c, c1 being Element of st not LIN a,a1,b & not LIN a,a1,c & a,a1 // b,b1 & a,a1 // c,c1 & a,b // a1,b1 & a,c // a1,c1 holds
b,c // b1,c1
let a1, b, b1, c, c1 be Element of ; ( not LIN a,a1,b & not LIN a,a1,c & a,a1 // b,b1 & a,a1 // c,c1 & a,b // a1,b1 & a,c // a1,c1 implies b,c // b1,c1 )
assume that
A2:
not LIN a,a1,b
and
A3:
not LIN a,a1,c
and
A4:
a,a1 // b,b1
and
A5:
a,a1 // c,c1
and
A6:
a,b // a1,b1
and
A7:
a,c // a1,c1
; b,c // b1,c1
reconsider a' = a, a1' = a1, b' = b, b1' = b1, c' = c, c1' = c1 as Element of by ANALMETR:47;
LIN a',a1',a1'
by AFF_1:16;
then consider A' being Subset of such that
A8:
A' is being_line
and
A9:
a' in A'
and
A10:
a1' in A'
and
a1' in A'
by AFF_1:33;
A11:
a',b' // a1',b1'
by A6, ANALMETR:48;
b,b1 // a,a1
by A4, ANALMETR:81;
then A12:
b',b1' // a',a1'
by ANALMETR:48;
A13:
a' <> a1'
then
for x' being Element of holds
( x' in A' iff LIN a',a1',x' )
by A8, A9, A10, AFF_1:33, AFF_1:39;
then
A' = Line a',a1'
by AFF_1:def 2;
then A14:
b',b1' // A'
by A13, A12, AFF_1:def 4;
A15:
a',c' // a1',c1'
by A7, ANALMETR:48;
c,c1 // a,a1
by A5, ANALMETR:81;
then A16:
c',c1' // a',a1'
by ANALMETR:48;
A17:
a' <> a1'
then
for x' being Element of holds
( x' in A' iff LIN a',a1',x' )
by A8, A9, A10, AFF_1:33, AFF_1:39;
then
A' = Line a',a1'
by AFF_1:def 2;
then A18:
c',c1' // A'
by A17, A16, AFF_1:def 4;
LIN c',c1',c1'
by AFF_1:16;
then consider N' being Subset of such that
A19:
N' is being_line
and
A20:
c' in N'
and
A21:
c1' in N'
and
c1' in N'
by AFF_1:33;
LIN b',b1',b1'
by AFF_1:16;
then consider M' being Subset of such that
A22:
M' is being_line
and
A23:
b' in M'
and
A24:
b1' in M'
and
b1' in M'
by AFF_1:33;
A25:
( A' <> M' & A' <> N' )
proof
assume
(
A' = M' or
A' = N' )
;
contradiction
then
(
LIN a',
a1',
b' or
LIN a',
a1',
c' )
by A8, A9, A10, A23, A20, AFF_1:33;
hence
contradiction
by A2, A3, ANALMETR:55;
verum
end;
A26:
c' <> c1'
proof
assume
c' = c1'
;
contradiction
then
c,
a // c,
a1
by A7, ANALMETR:81;
then
LIN c,
a,
a1
by ANALMETR:def 11;
then
LIN c',
a',
a1'
by ANALMETR:55;
then
LIN a',
a1',
c'
by AFF_1:15;
hence
contradiction
by A3, ANALMETR:55;
verum
end;
then
for x' being Element of holds
( x' in N' iff LIN c',c1',x' )
by A19, A20, A21, AFF_1:33, AFF_1:39;
then
N' = Line c',c1'
by AFF_1:def 2;
then A27:
A' // N'
by A18, A26, AFF_1:def 5;
A28:
b' <> b1'
proof
assume
b' = b1'
;
contradiction
then
b,
a // b,
a1
by A6, ANALMETR:81;
then
LIN b,
a,
a1
by ANALMETR:def 11;
then
LIN b',
a',
a1'
by ANALMETR:55;
then
LIN a',
a1',
b'
by AFF_1:15;
hence
contradiction
by A2, ANALMETR:55;
verum
end;
then
for x' being Element of holds
( x' in M' iff LIN b',b1',x' )
by A22, A23, A24, AFF_1:33, AFF_1:39;
then
M' = Line b',b1'
by AFF_1:def 2;
then
A' // M'
by A14, A28, AFF_1:def 5;
then
b',c' // b1',c1'
by A1, A8, A9, A10, A22, A23, A24, A19, A20, A21, A27, A25, A11, A15, AFF_2:def 11;
hence
b,c // b1,c1
by ANALMETR:48; verum