let M be non empty MetrSpace; :: thesis: for P, Q being non empty Subset of (TopSpaceMetr M) st P is compact & Q is compact & HausDist P,Q = 0 holds
P = Q
let P, Q be non empty Subset of (TopSpaceMetr M); :: thesis: ( P is compact & Q is compact & HausDist P,Q = 0 implies P = Q )
assume A1:
( P is compact & Q is compact )
; :: thesis: ( not HausDist P,Q = 0 or P = Q )
then A2:
( P is closed & Q is closed )
by COMPTS_1:16;
A3:
( max_dist_min P,Q >= 0 & max_dist_min Q,P >= 0 )
by A1, Th30;
assume
HausDist P,Q = 0
; :: thesis: P = Q
then
( max_dist_min P,Q = 0 & max_dist_min Q,P = 0 )
by A3, Th1;
then A4:
( upper_bound ((dist_min P) .: Q) = 0 & upper_bound ((dist_min Q) .: P) = 0 )
by WEIERSTR:def 10;
then consider X being non empty Subset of REAL such that
A5:
( (dist_min P) .: Q = X & 0 = sup X )
by Th13;
consider Y being non empty Subset of REAL such that
A6:
( (dist_min Q) .: P = Y & 0 = sup Y )
by A4, Th13;
A7:
Y is bounded_above
by A1, A6, Th27;
A8:
X is bounded_above
by A1, A5, Th27;
thus
P c= Q
:: according to XBOOLE_0:def 10 :: thesis: Q c= P
let x be set ; :: according to TARSKI:def 3 :: thesis: ( not x in Q or x in P )
assume A11:
x in Q
; :: thesis: x in P
then reconsider x' = x as Point of M by TOPMETR:16;
dom (dist_min P) = the carrier of (TopSpaceMetr M)
by FUNCT_2:def 1;
then
(dist_min P) . x in X
by A5, A11, FUNCT_1:def 12;
then A12:
(dist_min P) . x <= 0
by A5, A8, SEQ_4:def 4;
(dist_min P) . x >= 0
by A11, JORDAN1K:9;
then
(dist_min P) . x = 0
by A12, XXREAL_0:1;
then
x' in P
by A2, Th11;
hence
x in P
; :: thesis: verum