Let R be the realtion defined in the set `A = {1,2,3,4,5,6,7}` by `R ={(a,b):` both a and b are either odd or even}. Show that R is an equivalance relation. further, show that all the elements of the subset `{1, 3, 5, 7}` are related to each other and all elements of subset {2, 4, 6} are related to each other, but no element of the subset `{1,3,5,7}` is related to any element of the subset `{2,4,6}.`