let p be Point of (TOP-REAL 2); :: thesis: for C being compact Subset of (TOP-REAL 2) st p in BDD C holds
( North-Bound p,C in C & North-Bound p,C in north_halfline p & South-Bound p,C in C & South-Bound p,C in south_halfline p )
let C be compact Subset of (TOP-REAL 2); :: thesis: ( p in BDD C implies ( North-Bound p,C in C & North-Bound p,C in north_halfline p & South-Bound p,C in C & South-Bound p,C in south_halfline p ) )
assume A1:
p in BDD C
; :: thesis: ( North-Bound p,C in C & North-Bound p,C in north_halfline p & South-Bound p,C in C & South-Bound p,C in south_halfline p )
A2:
C is Bounded
by JORDAN2C:73;
set X = C /\ (north_halfline p);
not north_halfline p c= UBD C
by A1, Th12;
then
north_halfline p meets C
by JORDAN2C:137;
then A3:
not C /\ (north_halfline p) is empty
by XBOOLE_0:def 7;
A4:
C /\ (north_halfline p) c= C
by XBOOLE_1:17;
A5:
C /\ (north_halfline p) is Bounded
by A2, JORDAN2C:16, XBOOLE_1:17;
C /\ (north_halfline p) is closed
by TOPS_1:35;
then A6:
proj2 .: (C /\ (north_halfline p)) is closed
by A5, JCT_MISC:22;
proj2 .: (C /\ (north_halfline p)) is bounded
by A2, A4, JCT_MISC:23, JORDAN2C:16;
then
proj2 .: (C /\ (north_halfline p)) is bounded_below
by XXREAL_2:def 11;
then
inf (proj2 .: (C /\ (north_halfline p))) in proj2 .: (C /\ (north_halfline p))
by A3, A6, Lm2, RCOMP_1:31, RELAT_1:152;
then consider x being set such that
A7:
x in the carrier of (TOP-REAL 2)
and
A8:
x in C /\ (north_halfline p)
and
A9:
inf (proj2 .: (C /\ (north_halfline p))) = proj2 . x
by FUNCT_2:115;
reconsider x = x as Point of (TOP-REAL 2) by A7;
x in north_halfline p
by A8, XBOOLE_0:def 4;
then A10: x `1 =
p `1
by TOPREAL1:def 12
.=
(North-Bound p,C) `1
by EUCLID:56
;
x `2 =
inf (proj2 .: (C /\ (north_halfline p)))
by A9, PSCOMP_1:def 29
.=
(North-Bound p,C) `2
by EUCLID:56
;
then
x = North-Bound p,C
by A10, TOPREAL3:11;
hence
( North-Bound p,C in C & North-Bound p,C in north_halfline p )
by A8, XBOOLE_0:def 4; :: thesis: ( South-Bound p,C in C & South-Bound p,C in south_halfline p )
set X = C /\ (south_halfline p);
not south_halfline p c= UBD C
by A1, Th13;
then
south_halfline p meets C
by JORDAN2C:136;
then A11:
not C /\ (south_halfline p) is empty
by XBOOLE_0:def 7;
A12:
C /\ (south_halfline p) c= C
by XBOOLE_1:17;
A13:
C /\ (south_halfline p) is Bounded
by A2, JORDAN2C:16, XBOOLE_1:17;
C /\ (south_halfline p) is closed
by TOPS_1:35;
then A14:
proj2 .: (C /\ (south_halfline p)) is closed
by A13, JCT_MISC:22;
proj2 .: (C /\ (south_halfline p)) is bounded
by A2, A12, JCT_MISC:23, JORDAN2C:16;
then
proj2 .: (C /\ (south_halfline p)) is bounded_above
by XXREAL_2:def 11;
then
sup (proj2 .: (C /\ (south_halfline p))) in proj2 .: (C /\ (south_halfline p))
by A11, A14, Lm2, RCOMP_1:30, RELAT_1:152;
then consider x being set such that
A15:
x in the carrier of (TOP-REAL 2)
and
A16:
x in C /\ (south_halfline p)
and
A17:
sup (proj2 .: (C /\ (south_halfline p))) = proj2 . x
by FUNCT_2:115;
reconsider x = x as Point of (TOP-REAL 2) by A15;
x in south_halfline p
by A16, XBOOLE_0:def 4;
then A18: x `1 =
p `1
by TOPREAL1:def 14
.=
(South-Bound p,C) `1
by EUCLID:56
;
x `2 =
sup (proj2 .: (C /\ (south_halfline p)))
by A17, PSCOMP_1:def 29
.=
(South-Bound p,C) `2
by EUCLID:56
;
then
x = South-Bound p,C
by A18, TOPREAL3:11;
hence
( South-Bound p,C in C & South-Bound p,C in south_halfline p )
by A16, XBOOLE_0:def 4; :: thesis: verum