hw3-1

# hw3-1 - CSE105 Automata and Computability Theory Winter...

This preview shows pages 1–2. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: CSE105: Automata and Computability Theory Winter 2011 Homework #3 Due: Tuesday, February 1st, 2011 Problem 1 Pumping Lemma practice. For each of the following languages, and for a pump- ing length p , give a string w that can be used to establish that the language is not regular. For example, in class we used the string w = 0 p 1 p for the language L = w ∈ { , 1 } * w has as many s as 1 s . a. L a = n 1 n over Σ = { , 1 } . b. L b = a 1 b 2 c a + b > c over Σ = { , 1 , 2 } . c. L c = xx R over Σ = { a , b ,..., z } . Here x R denotes the symbol-by-symbol reverse of x . In other words, if x = x 1 x 2 ...x n then x R = x n x n- 1 ...x 1 . d. L d = 1 r r is prime over Σ = { 1 } . e. L e = m 1 n m is a multiple of n over Σ = { , 1 } . (Note that 0 is a multiple of every number.) Problem 2 Let REGEXP be the language of valid regular expressions over { a , b } . That is, REGEXP is the set of all strings over the symbols Σ = a , b , ( , ) , ∪ , * , , ∅ that are valid regular expressions. For example, the string “valid regular expressions....
View Full Document

• Spring '99
• Paturi
• Formal language, Formal languages, Regular expression, Regular language, Context-free grammar, valid regular expressions

{[ snackBarMessage ]}

### Page1 / 2

hw3-1 - CSE105 Automata and Computability Theory Winter...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online