let A = {1,2,3,4,5,6,7}, which of the following two is a partition giving rise to an equivalence relation? why?
(i) A₁ = {1,3,}, A₂= {2}, A₃ = {4,7}.
(ii) B₁ = {1,2,5,7}, B₂ = {3},B₃= {4,6}.