We have an order relation of Z+ x Z+ (where Z+ denotes the positive integers.)

(a,b) < (c,d) if either a - b < c -d or a -b = c - and b < d

is an order relation

(a) which elements have immediate predecessors?

(b) which elements have immediate successors?

(c) Does the set Z+ x Z+ have a smallest element?

Can someone help I am really lost of this one.