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Unformatted text preview: centre (0 , , 0) . 3.2 Constructing relations Just as for sets, we may construct new relations from old. We just give the deFnitions for binary relations. it is easy to extend the deFnitions to the n-ary case. D EFINITION 3.4 (B ASIC R ELATION O PERATORS ) Let R, S A 1 A 2 . DeFne the relations R S , R S and R , all with type A 1 A 2 , by 1. (Relation Union) ( a 1 , a 2 ) R S iff ( a 1 , a 2 ) R or ( a 1 , a 2 ) S ; 2. (Relation Intersection) ( a 1 , a 2 ) R S if and only if ( a 1 , a 2 ) R and ( a 1 , a 2 ) S ; 18...
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- Spring '09