Unformatted text preview: taaatcccccte. 2. Show that INIT and MIN preserve regular sets by using the fact that the class of regular sets is closed under h, h inverse and intersection. (hint: for MIN, think about valid computations for regular sets.) 3. Rearrange( 1 2 n a a a L ) is the set consisting of all strings obtained by rearranging the order of symbols in the string 1 2 n a a a L . For example, rearrange(0011)={0011, 0101, 0110, 1001, 1010, 1100}. Rearrange(L)={yy is in rearrange(x) for some x in L}. Prove that rearrange does not preserve regular sets. 4. Write a contextfree grammar for the language { } *  1 n n L a b c n = ≥ . 5. Write a contextfree grammar for the complement of { } *  1 n n L a b c n = ≥ . Do not forget the strings which are of the wrong format, i.e. not of the form a*b*c*. 6. Write a contextfree grammar for the language { }  either i j or j k i j k L a b c = ≠ ≠ ....
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This note was uploaded on 11/07/2009 for the course CS 3810 taught by Professor Hopcroft during the Fall '07 term at Cornell.
 Fall '07
 HOPCROFT

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