now :: thesis: {x} is connected
assume not {x} is connected ; :: thesis: contradiction
then consider P, Q being Subset of GX such that
A1: {x} = P \/ Q and
A2: P,Q are_separated and
A3: P <> {} GX and
A4: Q <> {} GX by Th15;
P <> Q
proof
assume not P <> Q ; :: thesis: contradiction
then A5: P /\ Q = P ;
P misses Q by A2, Th1;
hence contradiction by A3, A5; :: thesis: verum
end;
hence contradiction by A1, A3, A4, ZFMISC_1:38; :: thesis: verum
end;
hence for b1 being Subset of GX st b1 = {x} holds
b1 is connected ; :: thesis: verum