Lecture 6 : Oracle TMs , Diagonalization Limits , Space Complexity
نویسنده
چکیده
Definition 1.1. An oracle TM M ? is a Turing machine that an extra tape, called the oracle tape, as well as three special states, a query state qquery and two answer states qyes and qno. It is designed to be used with an oracle (or black box) that decides decides membership in some set of strings. When M ? enters the query state with a string z on its query tape, in the next step, the machine enters state qyes or qno depending on whether z is a member of the oracle set. Each oracle query takes one time step. We can have oracle NTMs as well as oracle TMs.
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