let X be OrtAfPl; :: thesis: ( X is satisfying_MH1 implies X is satisfying_OSCH )
assume A1: X is satisfying_MH1 ; :: thesis: X is satisfying_OSCH
let a1 be Element of X; :: according to CONMETR:def 7 :: thesis: for a2, a3, a4, b1, b2, b3, b4 being Element of X
for M, N being Subset of X st M _|_ N & a1 in M & a3 in M & b1 in M & b3 in M & a2 in N & a4 in N & b2 in N & b4 in N & not a4 in M & not a2 in M & not b2 in M & not b4 in M & not a1 in N & not a3 in N & not b1 in N & not b3 in N & a3,a2 // b3,b2 & a2,a1 // b2,b1 & a1,a4 // b1,b4 holds
a3,a4 // b3,b4

let a2, a3, a4, b1, b2, b3, b4 be Element of X; :: thesis: for M, N being Subset of X st M _|_ N & a1 in M & a3 in M & b1 in M & b3 in M & a2 in N & a4 in N & b2 in N & b4 in N & not a4 in M & not a2 in M & not b2 in M & not b4 in M & not a1 in N & not a3 in N & not b1 in N & not b3 in N & a3,a2 // b3,b2 & a2,a1 // b2,b1 & a1,a4 // b1,b4 holds
a3,a4 // b3,b4

let M, N be Subset of X; :: thesis: ( M _|_ N & a1 in M & a3 in M & b1 in M & b3 in M & a2 in N & a4 in N & b2 in N & b4 in N & not a4 in M & not a2 in M & not b2 in M & not b4 in M & not a1 in N & not a3 in N & not b1 in N & not b3 in N & a3,a2 // b3,b2 & a2,a1 // b2,b1 & a1,a4 // b1,b4 implies a3,a4 // b3,b4 )
assume A2: ( M _|_ N & a1 in M & a3 in M & b1 in M & b3 in M & a2 in N & a4 in N & b2 in N & b4 in N & not a4 in M & not a2 in M & not b2 in M & not b4 in M & not a1 in N & not a3 in N & not b1 in N & not b3 in N & a3,a2 // b3,b2 & a2,a1 // b2,b1 & a1,a4 // b1,b4 ) ; :: thesis: a3,a4 // b3,b4
then A3: ( M is being_line & N is being_line ) by ANALMETR:62;
reconsider b4' = b4, b1' = b1, b2' = b2, b3' = b3, a1' = a1, a2' = a2, a3' = a3, a4' = a4 as Element of (Af X) by ANALMETR:47;
reconsider M' = M, N' = N as Subset of (Af X) by ANALMETR:57;
A4: ( M' is being_line & N' is being_line ) by A3, ANALMETR:58;
not M' // N'
proof end;
then ex o' being Element of (Af X) st
( o' in M' & o' in N' ) by A4, AFF_1:72;
then consider o being Element of X such that
A5: ( o in M & o in N ) ;
reconsider o' = o as Element of (Af X) by ANALMETR:47;
A6: now
assume A7: b2 = b4 ; :: thesis: a3,a4 // b3,b4
A8: a1',a4' // a1',a2'
proof end;
A9: LIN o',a4',a2' by A2, A4, A5, AFF_1:33;
not LIN o',a1',a4'
proof
assume LIN o',a1',a4' ; :: thesis: contradiction
then ex A' being Subset of (Af X) st
( A' is being_line & o' in A' & a1' in A' & a4' in A' ) by AFF_1:33;
hence contradiction by A2, A4, A5, AFF_1:30; :: thesis: verum
end;
hence a3,a4 // b3,b4 by A2, A7, A8, A9, AFF_1:23; :: thesis: verum
end;
now
assume A10: b2 <> b4 ; :: thesis: a3,a4 // b3,b4
A11: now
assume A12: b1 = b3 ; :: thesis: a3,a4 // b3,b4
A13: not LIN o',a2',a1'
proof
assume LIN o',a2',a1' ; :: thesis: contradiction
then o',a2' // o',a1' by AFF_1:def 1;
hence contradiction by A2, A4, A5, AFF_1:62; :: thesis: verum
end;
A14: LIN o',a1',a3' by A2, A4, A5, AFF_1:33;
a2',a1' // a2',a3' hence a3,a4 // b3,b4 by A2, A12, A13, A14, AFF_1:23; :: thesis: verum
end;
now
assume A16: b1 <> b3 ; :: thesis: a3,a4 // b3,b4
ex d4' being Element of (Af X) st
( o' <> d4' & d4' in N' ) by A4, AFF_1:32;
then consider d4 being Element of X such that
A17: ( d4 in N & d4 <> o ) ;
reconsider d4' = d4 as Element of (Af X) by ANALMETR:47;
consider e1' being Element of (Af X) such that
A18: ( o' <> e1' & e1' in M' ) by A4, AFF_1:32;
reconsider e1 = e1' as Element of X by ANALMETR:47;
consider e2 being Element of X such that
A19: ( a1,a4 _|_ d4,e2 & e2 <> d4 ) by ANALMETR:51;
reconsider e2' = e2 as Element of (Af X) by ANALMETR:47;
not o',e1' // d4',e2'
proof end;
then consider d1' being Element of (Af X) such that
A24: ( LIN o',e1',d1' & LIN d4',e2',d1' ) by AFF_1:74;
reconsider d1 = d1' as Element of X by ANALMETR:47;
A25: a1,a4 _|_ d1,d4 then A26: ( d1 in M & a1,a4 _|_ d1,d4 ) by A4, A5, A18, A24, AFF_1:39;
consider e1' being Element of (Af X) such that
A27: ( o' <> e1' & e1' in N' ) by A4, AFF_1:32;
reconsider e1 = e1' as Element of X by ANALMETR:47;
consider e2 being Element of X such that
A28: ( a2,a1 _|_ d1,e2 & e2 <> d1 ) by ANALMETR:51;
reconsider e2' = e2 as Element of (Af X) by ANALMETR:47;
not o',e1' // e2',d1'
proof end;
then consider d2' being Element of (Af X) such that
A34: ( LIN o',e1',d2' & LIN e2',d1',d2' ) by AFF_1:74;
reconsider d2 = d2' as Element of X by ANALMETR:47;
A35: a2,a1 _|_ d2,d1 then A37: ( d2 in N & a2,a1 _|_ d2,d1 ) by A4, A5, A27, A34, AFF_1:39;
consider e1' being Element of (Af X) such that
A38: ( o' <> e1' & e1' in M' ) by A4, AFF_1:32;
reconsider e1 = e1' as Element of X by ANALMETR:47;
consider e2 being Element of X such that
A39: ( a3,a2 _|_ d2,e2 & e2 <> d2 ) by ANALMETR:51;
reconsider e2' = e2 as Element of (Af X) by ANALMETR:47;
not o',e1' // e2',d2'
proof end;
then consider d3' being Element of (Af X) such that
A42: ( LIN o',e1',d3' & LIN e2',d2',d3' ) by AFF_1:74;
reconsider d3 = d3' as Element of X by ANALMETR:47;
A43: a3,a2 _|_ d3,d2
proof
LIN d2',d3',e2' by A42, AFF_1:15;
then LIN d2,d3,e2 by ANALMETR:55;
then d2,d3 // d2,e2 by ANALMETR:def 11;
then d3,d2 // d2,e2 by ANALMETR:81;
hence a3,a2 _|_ d3,d2 by A39, ANALMETR:84; :: thesis: verum
end;
then A44: ( d3 in M & a3,a2 _|_ d3,d2 ) by A4, A5, A38, A42, AFF_1:39;
then A45: a3,a4 _|_ d3,d4 by A1, A2, A17, A26, A37, Def3;
A46: b1,b4 _|_ d1,d4 by A2, A25, ANALMETR:84;
A47: b2,b1 _|_ d2,d1 by A2, A35, ANALMETR:84;
A48: b3,b2 _|_ d3,d2 by A2, A43, ANALMETR:84;
A49: d3 <> d4 by A2, A4, A5, A17, A44, AFF_1:30;
b3,b4 _|_ d3,d4 by A1, A2, A17, A26, A37, A44, A46, A47, A48, Def3;
hence a3,a4 // b3,b4 by A45, A49, ANALMETR:85; :: thesis: verum
end;
hence a3,a4 // b3,b4 by A11; :: thesis: verum
end;
hence a3,a4 // b3,b4 by A6; :: thesis: verum