# Computer Science

posted by
**Yu**
.

I need some help about Turing Machines, and prove by reductions.

Here are the 2 questions:

1. Sketch the construction of a Turing Machine that decides the language

L = a^i where i is not prime.

2. Show that the language 2Strings is not recursive by reducing any one of the two lan-

guages Member or Halt, to 2Strings.

2Strings = a language with at least 2 distinct strings

Halt = {<M,w> | M halts on input w}

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Any help would be greatly appreciated!