Given a grammar of the form: -> | | | + > 0 1 | 2 |...19 where ! means negation (i.e., !3 means -3, 7 means -7 and so on). 1. Derive the string !!9+4-12 and evaluate it arithmetically (assume standard arithmetic mean- ings for all terminals while evaluating). 2. State whether it is ambiguous or unambiguous. If it is ambiguous give an equivalent unam- biguous grammar. If it is unambiguous, states all the precedences and associativities enforced by the grammar.

Given a grammar of the form: -> | | | + > 0 1 | 2 |...19 where ! means negation (i.e., !3 means -3, 7 means -7 and so on). 1. Derive the string !!9+4-12 and evaluate it arithmetically (assume standard arithmetic mean- ings for all terminals while evaluating). 2. State whether it is ambiguous or unambiguous. If it is ambiguous give an equivalent unam- biguous grammar. If it is unambiguous, states all the precedences and associativities enforced by the grammar.

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

See similar textbooks

Similar questions

For each of the following languages give a regular expression that describes it. 1- A1 = {w|w is a non-empty string over E = {0, 1}}. 2- A2= {w € {ab}* ]w contains an odd number of as and each a is followed by at least one b}. 3- A3 = {w € {ab}*| w does not contain three a's}
Exercise4: Consider the language L on = {0,1} with L= {w such that w starts with 1and ends with 00} 1. Find 3 strings accepted by the automaton 2. Show that the language L is regular
d. L = {ww | the same string back to back, > = {a,b,c}} Prove that the given language is not context-free.
Please quickly , thanks !!! 5a
Theoretical computer science Hello i need help with this task, 2.Part: Let L1, L2 and L3 be the following languages above the alphabet Σ= {a,b}: L1 = {s1 • aa • s2 | s1, s2 ∈ Σ* }, L2 = {ambn | m, n ∈ IN and m < n}, L3 = {s ∈ Σ* | s does not contain the substring aa}. Subtask (a): Its given the following strings: u1 = ∈, u2 = ab, u3 = aab and u4 = bb. (i) For each of these character strings ui, give the suffix set assigned to itSL1 (ui) on.(ii) For each of these character strings ui, give the suffix set assigned to itSL2 (ui) on.(iii) For each of these character strings ui, give the suffix set assigned to itSL3 (ui) on. Subtask (b): Answer the following questions and give reasons for each of them detailed.(i) Which Nerode index does the language L1 have?(ii) Which Nerode index does the language L2 have?(iii) What is the Nerode index of language L3?
Q 3. Draw a DFA that accepts the language L = {w | na(w) = n¿(w)±1 (mod 2)} over the alphabets E = {a,b}, where n,(w) denotes the number of occurrences of symbol s in string w.
Let L be the language defined by the regular expression: (cu ab u b)*bb (c U ab) (a) Write 10 distinct strings that belong to L. If such strings do not exist, explain why. (b) Write 10 distinct strings over alphabet {a, b, c} that do not belong to L. If such strings do not exist, explain why.
Formalize the following sentence in english: 3X. elephant(X)|
Q: Let Ls= {|R1 and R2 are regular expressions and L(R1) = L(R2)}. Ls is a language containing all strings that contain pairs of regular expressions that accept the same language. Show that Ls is decidable.
Formal Languages and Automata Theory a) Show that ℛ irrational numbers are uncountable (10 points). b) ? = {?2|? ∈ ?}, discuss either ? or ? is the bigger infinite set (10 points).
Consider the following regular expression over alphabet Σ = {a,b,c}: Σ∗a+Σ∗bc Provide two strings that are in the language L and two strings that are not in the language L. w∈L: w∈L: w /∈L: w /∈L: