CST229 Week 2 Questions or concern? Homework #1 due – Difference between permutation and no restrictions on using an element more than once. Code example: Generate all permutation Reading: Chapters 2 & 3 this week, Chapter 4 next week. Review of main topics for this class. – Languages (formal languages) – language definitions/notations (chapters 2, 3, 4) – Machines (chapters 5, 7, 14, 15) – Grammar (chapters 12, 13) Why the need for formal languages or grammars? Chapter 2 – language definitions (set notation & Kleene closure) In-Class Exercise Part a Chapter 3 – recursive definitions In-Class Exercise Part b & c

In-Class Exercise #2 part a Let S1 = {aa, b}, how many words of length 2 does S1* have? Length 3? Length 4? Let S2 = {aa, aba, baa}, let L2 = S* is aabaa  L2? is baaabaaa  L2? is baaaaababaaa  L2? If S = {ab, bb} & T = {ab, bb, bbbb}, is S* = T*?

In-Class Exercise 2 part b Write a recursive function in C/C++ to compute if a word is a palindrome? bool isPal(char * word,.....

In-Class Exercise 2 part c Use recursive definition to show that all numbers end in the digits 0, 2, 4, 6, 8 are even