Usually, each individual database does not contain duplicate records, once we know r 1 is linked to r 1 , we can infer the rest candidate pairs should not be linked.
only if we are confident that no pair in the set {(r 1 , r 2 ), (r 1 , r 3 ), (r 2 , r 1 ), (r 3 , r 1 )} is not linked, r 1 is likely to be linked with r 1 .