6. Describe with regular expressions and with words, the languages ac- cepted by the NFAs below....
Regular expressions, DFA, NFA, grammars, languages Regular Languages 4 4 1. Write English descriptions for the languages generated by the following regular expressions: (a) (01... 9|A|B|C|D|E|F)+(2X) (b) (ab)*(a|ble) 2. Write regular expressions for each of the following. (a) All strings of lowercase letters that begin and end in a. (b) All strings of digits that contain no leading zeros. (c) All strings of digits that represent even numbers. (d) Strings over the alphabet {a,b,c} with an even number of a's....
Webber Chap. 7 Exercise 2 For each of these regular expressions, give two NFAs: the exact one constructed by the proof of Lemma 7.1, and the smallest one you can think of. d. 0 + 1 e. (00)* f. ab*
2. Properties of the following: (a) Regular languages (b) Context-free languages (c) Regular expressions (d) Non-deterministic finite automaton (e) Turing-recognizable and Turing-decidable languages (f) A <m B and what we can then determine (g) A <p B and what we can then determine (h) NP-hard and NP-complete.
4 Consider the FA below. 92 931 Compute: Regular expressions for all R . Regular expressions for all Ri 4 Consider the FA below. 92 931 Compute: Regular expressions for all R . Regular expressions for all Ri
Question 1 - Regular Expressions Find regular expressions that define the following languages: 1. All even-length strings over the alphabet {a,b}. 2. All strings over the alphabet {a,b} with odd numbers of a's. 3. All strings over the alphabet {a,b} with even numbers of b’s. 4. All strings over the alphabet {a,b} that start and end with different symbols. 5. All strings over the alphabet {a, b} that do not contain the substring aab and end with bb.
This question deals with NFAs, DFAs, and regular expressions. (a) Using only the symbols described in the lecture slides, write a regular expression that describes all strings over the alphabet Σ = {0,1} that are at are at least four bits long and begin and end with the same bit. (b) Draw a DFA, that accepts strings strings over the alphabet Σ = {0, 1} such that if you read the string from left to right, the difference between the...
1. Write regular expressions to capture the following regular languages: (a) The set of binary strings which have a 1 in every even position. (Note: odd positions may be either 0 or 1.) (b) The set of binary strings that do not contain 011 as a substring. (c) Comments in Pascal. These are delimited by (* and *) or by { and }, and can contain anything in between; they are NOT allowed to nest, however. 2. Write a DFA...
Give English descriptions of the languages represented by the following regular expressions. The descriptions should be simple, similar to how we have been defining languages in class(e.g., “languages of binary strings containing 0 in even positions. . .”). Note: While describing your language, you don’t want to simply spell out the conditions in your regular expressions. E.g., if the regular expression is 0(0 + 1)∗, an answer of the sort “language of all binary strings that start with a 0”...
Find regular expressions for the languages accepted by the following automata(b and c) (b) (c)
give the regular expressions for each of the following languages u.{xy {a, b}* | the number of as in x is odd and the number of bs in y is even}