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[主观题]
设有X={a,b,c}上关系R1,R2,R3,R4为: (1)R1={(a,b),(a,c),(c,b)}; (2)R2={(a,b),(b,c),(c,c)}; (3)R3={(a
设有X={a,b,c}上关系R1,R2,R3,R4为:
(1)R1={(a,b),(a,c),(c,b)};
(2)R2={(a,b),(b,c),(c,c)};
(3)R3={(a,b),(b,a)(c,c)};
(4)R4={(a,b),(b,c)(c,a)}.
求它们的传递闭包:t(R1),t(R2),t(R3),t(R4).
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