You are given, as input, some Turing Machine M and some string w. The problem is to determine whether the machine M, when executed on the input string w, ever moves its read-head to the left. Explain why the following algorithm is faulty:

if (some delta-rule in M has an L in the last entry of the 5-tuple of that delta-rule)

-->then when M is executed on w, the read-head will move left at some time during the computation.

--> --> else when M is executed on w, the read-head NEVER moves left during the computation.

Thanks a lot for your help!8