Exam 12: Models of Computation

The real value of Turing machines as models of computability is in exposing problems that are ____________________.

It is important to note that unsolvable problems related to the halting problem are unsolvable because of their ____.

Unsolvable problems related to the halting problem have the following practical consequence: ____.

The proof by ____ approach assumes that a specific Turing machine does exist and then shows that this assumption leads to an impossible situation.

The term unary means that we will use ____ symbol(s).

The Turing machine contains a single unit for both input and output.

At any point in time, only a finite number of cells in the Turing machine input contain ____ symbols.

What are four characteristics of the model of a physical or social phenomenon?

The equation for the distance d that a moving vehicle travels-the product of rate r and time t -is considered to be a model.

If we post a program and try to construct a Turing machine to solve it but are not successful, does this prove that no Turing machine exists? If not, why would prove this?

We assumed that there was a Turing machine that could solve the halting problem, and this assumption led to a(n)____.

In a _______ diagram, circles are used to represent states.

A formal basis for proofs might allow for ____ theorem-proving.

The ____ thesis can never be proved because the definition of an algorithm is descriptive, not mathematical.

We can write a Turing machine to add 1 to any number; such a machine is often called a(n)____.

One consequence of a(n)____________________ problem related to the halting problem is that no program can be written to decide whether any given program always stops eventually, no matter what the input is.

In binary representation, any unsigned whole number n is encoded by a sequence of n + 1 1s. _________________________

It's possible to compare the efficiency of a Turing machine algorithm with an algorithm that runs on a "real" computer.

In what ways are a Turing machine and an algorithm identical?

The symbols for a Turing machine must come from a finite set of symbols called the tape ____.