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3 votes
3 votes
If a language(L1) is Recursive enumerable  (RE)  and  L2 is Recursive   (REC)  , then  what  will be L1 - L2  ? Can we  directly use set difference property   or do the so called  intersection method  i.e  L1 - L2 = L1 ∩ L2 .

2 Answers

1 votes
1 votes

L1 = RE
L2 = REC
L1-L2 = L1 ∩ L2c = RE ∩ REC = RE ∩ RE = RE

As, REC is closed under complement and RE is closed under intersection.

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