... a S } 14 Bao đóng quan hệ Ví dụ: R = { (1, 2), (2, 2), (2, 3) } S = {1, 2, 3} • R+ = { (1, 2), (2, 2), (2, 3), (1, 3) } • R* = { (1, 1) , (1, 2), (1, 3), (2, 2), (2, 3), (3, 3) } 15 Nguyên ... (0, 1) , (0, 2), (0, 3), (1, 2), (1, 3), (2, 3) } • Quan hệ ‘bằng’ E = { (0, 0), (1, 1) , (2, 2), (3, 3) } • Quan hệ ‘chẵn lẻ’ P = { (0, 0), (1, 1) , (2, 2), (3, 3), (0, 2), (2, 0), (1, 3), (3, 1) } ... A\B= {1} • A x B = { (1, 2 ), (1, 3), (2, 2), (2, 3) } • 2A = { , {1} , {2}, {1, 2} } Quan hệ S R ( A B ) = aRb miền xác định (domain) miền giá trị (range) Quan hệ Ví dụ: cho S = {0, 1, 2,...