CS 30 Homework 8

Due by the beginning of class Tuesday, November 5
  1. Read the article Computer Science as Empirical Inquiry: Symbols and Search by Allen Newell and Herbert A. Simon, which was handed out in class.

  2. Read the article Minds, Brains, and Programs by John R. Searle, which was handed out in class.

  3. These are among the most famous articles in artificial intelligence and cognitive science. I'd like you to write a page or two of reactions to the ideas discussed in them. The Newell and Simon article presents their physical symbol system hypothesis, which claims that intelligence can—indeed, can only—be realized within a "physical symbol system". The Searle article uses a thought experiment called the Chinese Room to argue against the idea of intelligence as symbol-manipulation. Which argument (if any) seems more persuasive to you? Why? In your reactions, identify two or three weaknesses or criticisms of each article.

    Be prepared to discuss these articles in class next week. I will also post everyone's written reactions on the CS 30 Web page, so that you can see what your classmates had to say.

  4. Study the code for the Turing machine simulator developed in class Thursday (utm.scm). The file machines.scm contains descriptions of the other TMs we experimented with in lab this week. Try these out with the UTM program. Don't forget to include enough extra blanks on the input tape for the machines to work properly.

    Next, modify the UTM code so that it keeps track of the total number of steps (i.e., left/right moves) performed by a machine and then prints this total out when the machine halts. For example, the inverter-tm machine runs for 6 steps on the input string 11001.

  5. How many steps does the palindrome-tm machine take to determine that the string 111000111 is indeed a palindrome? How many steps does the copier-tm machine take to make a copy of this string? (Important: don't forget to include the ! end-marker symbol on the input tape.) How many steps does minus-tm take to perform the subtraction 8 - 5? Include your answers in a comment at the top of your modified utm.scm file.

  6. Read Chapter 9 of The Little Schemer.

Turning in your homework

Write up your reactions from Part 3 as either a Microsoft Word file or a plain text file. Put this file into a folder called Your name HW 8, along with your utm.scm file from Parts 4-5, and drop it into the drop folder. You do not need to turn in a hardcopy.