let P be non empty compact Subset of (TOP-REAL 2); :: thesis: for q1, q2 being Point of (TOP-REAL 2) st P is being_simple_closed_curve & LE q1,q2,P & q1 <> q2 & q1 <> W-min P holds
(Segment q2,(W-min P),P) /\ (Segment (W-min P),q1,P) = {(W-min P)}
let q1, q2 be Point of (TOP-REAL 2); :: thesis: ( P is being_simple_closed_curve & LE q1,q2,P & q1 <> q2 & q1 <> W-min P implies (Segment q2,(W-min P),P) /\ (Segment (W-min P),q1,P) = {(W-min P)} )
assume A1:
( P is being_simple_closed_curve & LE q1,q2,P & q1 <> q2 & q1 <> W-min P )
; :: thesis: (Segment q2,(W-min P),P) /\ (Segment (W-min P),q1,P) = {(W-min P)}
then A2:
( q1 in P & q2 in P )
by Th5;
thus
(Segment q2,(W-min P),P) /\ (Segment (W-min P),q1,P) c= {(W-min P)}
:: according to XBOOLE_0:def 10 :: thesis: {(W-min P)} c= (Segment q2,(W-min P),P) /\ (Segment (W-min P),q1,P)proof
let x be
set ;
:: according to TARSKI:def 3 :: thesis: ( not x in (Segment q2,(W-min P),P) /\ (Segment (W-min P),q1,P) or x in {(W-min P)} )
assume
x in (Segment q2,(W-min P),P) /\ (Segment (W-min P),q1,P)
;
:: thesis: x in {(W-min P)}
then A3:
(
x in Segment q2,
(W-min P),
P &
x in Segment (W-min P),
q1,
P )
by XBOOLE_0:def 4;
then
x in { p1 where p1 is Point of (TOP-REAL 2) : ( LE q2,p1,P or ( q2 in P & p1 = W-min P ) ) }
by Def1;
then consider p1 being
Point of
(TOP-REAL 2) such that A4:
(
p1 = x & (
LE q2,
p1,
P or (
q2 in P &
p1 = W-min P ) ) )
;
now per cases
( LE q2,p1,P or ( q2 in P & p1 = W-min P ) )
by A4;
case A5:
LE q2,
p1,
P
;
:: thesis: contradiction
x in { p where p is Point of (TOP-REAL 2) : ( LE W-min P,p,P & LE p,q1,P ) }
by A1, A3, Def1;
then
ex
p2 being
Point of
(TOP-REAL 2) st
(
p2 = x &
LE W-min P,
p2,
P &
LE p2,
q1,
P )
;
then
LE q2,
q1,
P
by A1, A4, A5, JORDAN6:73;
hence
contradiction
by A1, JORDAN6:72;
:: thesis: verum end; end; end;
hence
x in {(W-min P)}
by TARSKI:def 1;
:: thesis: verum
end;
let x be set ; :: according to TARSKI:def 3 :: thesis: ( not x in {(W-min P)} or x in (Segment q2,(W-min P),P) /\ (Segment (W-min P),q1,P) )
assume
x in {(W-min P)}
; :: thesis: x in (Segment q2,(W-min P),P) /\ (Segment (W-min P),q1,P)
then A6:
x = W-min P
by TARSKI:def 1;
then
x in { p1 where p1 is Point of (TOP-REAL 2) : ( LE q2,p1,P or ( q2 in P & p1 = W-min P ) ) }
by A2;
then A7:
x in Segment q2,(W-min P),P
by Def1;
LE W-min P,q1,P
by A1, A2, Th3;
then
x in Segment (W-min P),q1,P
by A1, A6, Th6;
hence
x in (Segment q2,(W-min P),P) /\ (Segment (W-min P),q1,P)
by A7, XBOOLE_0:def 4; :: thesis: verum