let P be non empty compact Subset of (TOP-REAL 2); for q1, q2 being Point of (TOP-REAL 2) st P is being_simple_closed_curve & LE q1,q2,P & q1 <> W-min P & q2 <> W-min P holds
(Segment (q1,q2,P)) /\ (Segment (q2,(W-min P),P)) = {q2}
let q1, q2 be Point of (TOP-REAL 2); ( P is being_simple_closed_curve & LE q1,q2,P & q1 <> W-min P & q2 <> W-min P implies (Segment (q1,q2,P)) /\ (Segment (q2,(W-min P),P)) = {q2} )
set q3 = W-min P;
assume that
A1:
P is being_simple_closed_curve
and
A2:
LE q1,q2,P
and
A3:
q1 <> W-min P
and
A4:
not q2 = W-min P
; (Segment (q1,q2,P)) /\ (Segment (q2,(W-min P),P)) = {q2}
thus
(Segment (q1,q2,P)) /\ (Segment (q2,(W-min P),P)) c= {q2}
XBOOLE_0:def 10 {q2} c= (Segment (q1,q2,P)) /\ (Segment (q2,(W-min P),P))proof
let x be
object ;
TARSKI:def 3 ( not x in (Segment (q1,q2,P)) /\ (Segment (q2,(W-min P),P)) or x in {q2} )
assume A5:
x in (Segment (q1,q2,P)) /\ (Segment (q2,(W-min P),P))
;
x in {q2}
then
x in Segment (
q2,
(W-min P),
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 A6:
p1 = x
and A7:
(
LE q2,
p1,
P or (
q2 in P &
p1 = W-min P ) )
;
x in Segment (
q1,
q2,
P)
by A5, XBOOLE_0:def 4;
then
p1 in { p where p is Point of (TOP-REAL 2) : ( LE q1,p,P & LE p,q2,P ) }
by A4, A6, Def1;
then A8:
ex
p being
Point of
(TOP-REAL 2) st
(
p = p1 &
LE q1,
p,
P &
LE p,
q2,
P )
;
end;
let x be object ; TARSKI:def 3 ( not x in {q2} or x in (Segment (q1,q2,P)) /\ (Segment (q2,(W-min P),P)) )
assume
x in {q2}
; x in (Segment (q1,q2,P)) /\ (Segment (q2,(W-min P),P))
then A9:
x = q2
by TARSKI:def 1;
q2 in P
by A1, A2, Th5;
then A10:
x in Segment (q2,(W-min P),P)
by A1, A9, Th7;
x in Segment (q1,q2,P)
by A1, A2, A9, Th6;
hence
x in (Segment (q1,q2,P)) /\ (Segment (q2,(W-min P),P))
by A10, XBOOLE_0:def 4; verum