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Numbering computable functions

  1. NOTE: MISTAKE IN WHAT WAS DONE IN THE CLASS

    the bijection tex2html_wrap_inline219 should be defined as

    displaymath215

    Only then the bijection given in the class holds. Work out the complete proof that tex2html_wrap_inline221 is an effective bijection. How come nobody pointed out the mistake in the class?

  2. Find
    1. tex2html_wrap_inline223
    2. tex2html_wrap_inline225
    3. the code of the following program:

      displaymath216

    4. tex2html_wrap_inline227
  3. Prove that every computable function has infinitely many indices.
  4. Suppose that f(x,y) is a total computable function. For each m, let tex2html_wrap_inline233 be the computable function given by tex2html_wrap_inline235 . Construct a total computable function h such that for each m, tex2html_wrap_inline241 .
  5. Let tex2html_wrap_inline243 be an enumeration of partial functions from tex2html_wrap_inline245 to tex2html_wrap_inline245 . Construct a function g from tex2html_wrap_inline245 to tex2html_wrap_inline245 such that tex2html_wrap_inline255 for each i.
  6. Let f be a partial function from tex2html_wrap_inline245 to tex2html_wrap_inline245 , and let tex2html_wrap_inline143 . Construct a non-computable function g such that tex2html_wrap_inline269 for tex2html_wrap_inline271 .
  7. Show that the set of all functions from tex2html_wrap_inline245 to tex2html_wrap_inline245 is not denumerable.


Subhashis Banerjee
Fri Sep 5 15:54:45 IST 1997