[Solved]: Can a Turing machine decide if a LOOP program stops for the integer input 0

Problem Detail: This is a question I found in a practice exam while I am preparing for my mid term exam. The answer needs justification, either a pseudo code or a logical explanation why not. What puzzled me about that question is that we already know that all LOOP programs terminate at some point, the question seems odd to me. Any references about LOOP and/or WHILE programs are welcome. Our professor didn’t give much.

Asked By : Zack Soliman

Answered By : Yuval Filmus

If all LOOP programs terminate that there is a Turing machine that decides whether a LOOP program stops on input 0: it just always accepts. For WHILE programs the picture is rather different – I’ll let you find out yourself. (Perhaps your professor really meant WHILE programs.)
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