file: oct28.txt
Posted on wed 28 oct 2026

We review the book.
See statements below.

We read Homework7.pdf. Each problem is worth 12 points and the readMe.txt is worth 2 points.

Homework07.pdf is supplied on 4 picture slides if your browser did not render it.

We get help on Problem 2.

For Problem 2, you are inferring the grammar rules.

Here is the G Grammar:
s -> if<eol>M200
M -> _M_|100else<eol>

Be sure you understand how to come up with these rules from what you are given.

Then create your own examples in the examples table.

Review of Book:
Chapter 0.1, p1: What are the fundamental capabilities and limitations of computers?

Since the 1930s, our ability to compute has increased a lot.

There are 3 central areas:
automata,
computabiity and
complexity.

Complexity: What makes some problems computationally hard and other problems easy?  We don't know, but we can classify problems according ot computational difficulty.  In cryptography, hard problems are required. (Sipser, p2).

Computability Theory: "During the first half of the twentieth century, mathematicians - Kurt Godel, Alan Turing and Alonzo Church - discovered that certain basic problems cannot be solved by computers."  For instance, a computer cannot say whether a statement is true or false.  We classify problems by those that are solveable and those that are not.  We will need a precise definition of a computer (Sipser, p3).

Automata Theory.  We look at definitions and properties of mathematical models of computation.  Finite automata are used in text processing, compilers and hardware design.  Another model, context-free grammar, is used in programming languages and artificial intelligence.  Automata theory allows practice with formal definitions.