let p be Point of (TOP-REAL 2); :: thesis: for C being compact Subset of (TOP-REAL 2) st p in BDD C holds
( (South-Bound p,C) `2 < p `2 & p `2 < (North-Bound p,C) `2 )
let C be compact Subset of (TOP-REAL 2); :: thesis: ( p in BDD C implies ( (South-Bound p,C) `2 < p `2 & p `2 < (North-Bound p,C) `2 ) )
assume A1:
p in BDD C
; :: thesis: ( (South-Bound p,C) `2 < p `2 & p `2 < (North-Bound p,C) `2 )
A2:
(South-Bound p,C) `2 = sup (proj2 .: (C /\ (south_halfline p)))
by EUCLID:56;
A3:
South-Bound p,C in C
by A1, Th22;
South-Bound p,C in south_halfline p
by A1, Th22;
then
South-Bound p,C in C /\ (south_halfline p)
by A3, XBOOLE_0:def 4;
then A4:
not proj2 .: (C /\ (south_halfline p)) is empty
by Lm2, RELAT_1:152;
A5:
proj2 .: (south_halfline p) is bounded_above
by Th5;
C /\ (south_halfline p) c= south_halfline p
by XBOOLE_1:17;
then A6:
sup (proj2 .: (C /\ (south_halfline p))) <= sup (proj2 .: (south_halfline p))
by A4, A5, RELAT_1:156, SEQ_4:65;
A7:
sup (proj2 .: (south_halfline p)) = p `2
by Th9;
A8:
BDD C misses C
by JORDAN1A:15;
hence
(South-Bound p,C) `2 < p `2
by A2, A6, A7, XXREAL_0:1; :: thesis: p `2 < (North-Bound p,C) `2
( North-Bound p,C in C & North-Bound p,C in north_halfline p )
by A1, Th22;
then
not C /\ (north_halfline p) is empty
by XBOOLE_0:def 4;
then A10:
not proj2 .: (C /\ (north_halfline p)) is empty
by Lm2, RELAT_1:152;
A11:
proj2 .: (north_halfline p) is bounded_below
by Th4;
C /\ (north_halfline p) c= north_halfline p
by XBOOLE_1:17;
then A12:
inf (proj2 .: (C /\ (north_halfline p))) >= inf (proj2 .: (north_halfline p))
by A10, A11, RELAT_1:156, SEQ_4:64;
A13:
inf (proj2 .: (north_halfline p)) = p `2
by Th8;
A14:
(North-Bound p,C) `2 = inf (proj2 .: (C /\ (north_halfline p)))
by EUCLID:56;
hence
p `2 < (North-Bound p,C) `2
by A12, A13, A14, XXREAL_0:1; :: thesis: verum