let X be OrtAfPl; :: thesis: ( Af X is translational implies X is satisfying_des )
assume A1:
Af X is translational
; :: thesis: X is satisfying_des
let a be Element of X; :: according to CONMETR:def 8 :: thesis: for a1, b, b1, c, c1 being Element of X 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 X; :: thesis: ( 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 A2:
( 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 )
; :: thesis: b,c // b1,c1
reconsider a' = a, a1' = a1, b' = b, b1' = b1, c' = c, c1' = c1 as Element of (Af X) by ANALMETR:47;
LIN a',a1',a1'
by AFF_1:16;
then consider A' being Subset of (Af X) such that
A3:
( A' is being_line & a' in A' & a1' in A' & a1' in A' )
by AFF_1:33;
LIN b',b1',b1'
by AFF_1:16;
then consider M' being Subset of (Af X) such that
A4:
( M' is being_line & b' in M' & b1' in M' & b1' in M' )
by AFF_1:33;
LIN c',c1',c1'
by AFF_1:16;
then consider N' being Subset of (Af X) such that
A5:
( N' is being_line & c' in N' & c1' in N' & c1' in N' )
by AFF_1:33;
A6:
A' // M'
proof
A7:
a' <> a1'
then
for
x' being
Element of
(Af X) holds
(
x' in A' iff
LIN a',
a1',
x' )
by A3, AFF_1:33, AFF_1:39;
then A8:
A' = Line a',
a1'
by AFF_1:def 2;
b,
b1 // a,
a1
by A2, ANALMETR:81;
then
b',
b1' // a',
a1'
by ANALMETR:48;
then A9:
b',
b1' // A'
by A7, A8, AFF_1:def 4;
A10:
b' <> b1'
proof
assume
b' = b1'
;
:: thesis: contradiction
then
b,
a // b,
a1
by A2, 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;
:: thesis: verum
end;
then
for
x' being
Element of
(Af X) holds
(
x' in M' iff
LIN b',
b1',
x' )
by A4, AFF_1:33, AFF_1:39;
then
M' = Line b',
b1'
by AFF_1:def 2;
hence
A' // M'
by A9, A10, AFF_1:def 5;
:: thesis: verum
end;
A11:
A' // N'
proof
A12:
a' <> a1'
A13:
A' = Line a',
a1'
c',
c1' // a',
a1'
then A14:
c',
c1' // A'
by A12, A13, AFF_1:def 4;
A15:
c' <> c1'
proof
assume
c' = c1'
;
:: thesis: contradiction
then
c,
a // c,
a1
by A2, 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 A2, ANALMETR:55;
:: thesis: verum
end;
N' = Line c',
c1'
hence
A' // N'
by A14, A15, AFF_1:def 5;
:: thesis: verum
end;
A16:
( A' <> M' & A' <> N' )
A17:
a',b' // a1',b1'
by A2, ANALMETR:48;
a',c' // a1',c1'
by A2, ANALMETR:48;
then
b',c' // b1',c1'
by A1, A3, A4, A5, A6, A11, A16, A17, AFF_2:def 11;
hence
b,c // b1,c1
by ANALMETR:48; :: thesis: verum