Let #a# is real number and #epsilon>0#. Defined that #V_epsilon(a)={x:|x-a|<"epsilon}#. If #a!=b#, how to determine #epsilon>0# and #delta>0# so that #V_epsilon(a)nnV_delta(b)=O/# ?

#a#
#epsilon>0#
#V_epsilon(a)={x:|x-a|<"epsilon}#
#a!=b#
#epsilon>0#
#delta>0#
#V_epsilon(a) nn V_delta(b)=O/#