let P be non empty compact Subset of (TOP-REAL 2); :: thesis: for q being Point of (TOP-REAL 2) st P is being_simple_closed_curve & q in P & q <> W-min P holds
Segment q,q,P = {q}
let q be Point of (TOP-REAL 2); :: thesis: ( P is being_simple_closed_curve & q in P & q <> W-min P implies Segment q,q,P = {q} )
assume that
A1:
P is being_simple_closed_curve
and
A2:
q in P
and
A3:
q <> W-min P
; :: thesis: Segment q,q,P = {q}
for x being set holds
( x in Segment q,q,P iff x = q )
proof
let x be
set ;
:: thesis: ( x in Segment q,q,P iff x = q )
hereby :: thesis: ( x = q implies x in Segment q,q,P )
assume
x in Segment q,
q,
P
;
:: thesis: x = qthen
x in { p where p is Point of (TOP-REAL 2) : ( LE q,p,P & LE p,q,P ) }
by A3, Def1;
then
ex
p being
Point of
(TOP-REAL 2) st
(
p = x &
LE q,
p,
P &
LE p,
q,
P )
;
hence
x = q
by A1, JORDAN6:72;
:: thesis: verum
end;
assume A4:
x = q
;
:: thesis: x in Segment q,q,P
LE q,
q,
P
by A1, A2, JORDAN6:71;
then
x in { p where p is Point of (TOP-REAL 2) : ( LE q,p,P & LE p,q,P ) }
by A4;
hence
x in Segment q,
q,
P
by A3, Def1;
:: thesis: verum
end;
hence
Segment q,q,P = {q}
by TARSKI:def 1; :: thesis: verum