Homework 2: Evaluating Boolean Propositions

Summary: In this assignment, you will develop a program that shows the steps involved in evaluating a Boolean proposition in a particular state.

Assigned: Wednesday, 22 January 2003.

Due: Tuesday, 28 January 2003.

Collaboration: You may work in groups of up to size three. You may also work alone.

Formatting Guidelines:

• Include an introductory comment that gives your name and any instructions for running your program. If you write in Java, you should use Javadoc-style comments.
• Comment each procedure you write.
• No line should have more than eighty characters.
• Use a reasonable indentation style that reflects the structure of the program.
• In Java, avoid code that follows an open brace on the same line.

Submitting Your Work: Submit your source code with the ECA. If you can't get it to work, email me your source code.

Assignment

Write (in Scheme or Java) a program that takes a Boolean expression (fully parenthesized, in infix form) and a state (a mapping of variable names to true or false) and shows the steps in evaluating that expression.

Your program need not be efficient. For example, here's a sketch of one technique

Replace all variables in P by the corresponding values
while P is neither true nor false
  Print P
  Find the innermost non-trivial sub-proposition
  Replace that sub-proposition by its value