consider x being object such that
A1: x in the carrier of M by XBOOLE_0:def 1;
reconsider x = x as Point of M by A1;
set B = Ball (x,1);
take S = NAT --> (Ball (x,1)); :: thesis: ( S is non-empty & S is pointwise_bounded & S is open )
A2: now :: thesis: for y being object st y in dom S holds
not S . y is empty
let y be object ; :: thesis: ( y in dom S implies not S . y is empty )
assume y in dom S ; :: thesis: not S . y is empty
then reconsider n = y as Element of NAT ;
A3: Ball (x,1) = S . n by FUNCOP_1:7;
dist (x,x) = 0 by METRIC_1:1;
hence not S . y is empty by A3, METRIC_1:11; :: thesis: verum
end;
A4: now :: thesis: for i being Nat holds S . i is open end;
for i being Nat holds S . i is bounded by FUNCOP_1:7, ORDINAL1:def 12;
hence ( S is non-empty & S is pointwise_bounded & S is open ) by A2, A4, FUNCT_1:def 9; :: thesis: verum