let n be Nat; for A, B being Subset of (COMPLEX n) st A meets B holds
dist (A,B) = 0
let A, B be Subset of (COMPLEX n); ( A meets B implies dist (A,B) = 0 )
assume
A meets B
; dist (A,B) = 0
then consider z being object such that
A1:
z in A
and
A2:
z in B
by XBOOLE_0:3;
reconsider z = z as Element of COMPLEX n by A1;
( dist (z,A) = 0 & dist (z,B) = 0 )
by A1, A2, Th115;
then
0 + 0 >= dist (A,B)
by A1, A2, Th128;
hence
dist (A,B) = 0
by A1, A2, Th126; verum