Tag: regular languages

What Is Regular Language In Theory Of Computation?

A is

a language that can be expressed with a or a deterministic or

non-deterministic or state machine. … are used in parsing and designing programming languages and are one of the first concepts taught in computability courses.

What is regular expression in theory of computation?

The language accepted by finite automata can be easily described by simple expressions called Regular Expressions. A regular expression can also be described as

a sequence of pattern that defines a string

. … Regular expressions are used to match character combinations in strings.

What is language in theory of computing?

A language is

a set of string all of which are chosen from some ∑*, where ∑ is a particular alphabet

. This means that language L is subset of ∑*. An example is English language, where the collection of legal English words is a set of strings over the alphabet that consists of all the letters.

What are regular languages in computer science?

In theoretical computer science and formal language theory, a regular language (also called a rational language) is

a formal language that can be defined by a regular expression, in the strict sense in

theoretical computer science (as opposed to many modern regular expressions engines, which are augmented with features …

What is regular language give example?

For example,

let = {a, b}

. Then since {a} and {b} are regular languages, {a, b} ( = {a} {b} ) and {ab} ( = {a}{b} ) are regular languages. Also since {a} is regular, {a}

*

is a regular language which is the set of strings consisting of a’s such as , a, aa, aaa, aaaa etc.

Is Sigma a regular star?

Well, the alphabet Sigma is finite, and therefore

regular

, and the star operation preserves regularity (by the definition of regular languages).

What is difference between DFA and NFA?

SR.NO. DFA NFA 9 All DFA are NFA. Not all NFA are DFA. 10 DFA requires more space. NFA requires less space then DFA.

What we mean by algorithms?

An algorithm is

a set of instructions for solving a problem or accomplishing a task

. One common example of an algorithm is a recipe, which consists of specific instructions for preparing a dish or meal. Every computerized device uses algorithms to perform its functions.

What is the importance of theory of computation?

The importance to study the theory of computation is

to better understand the development of formal mathematical models of computation that reflect the real-world of computer

. To achieve deep understanding about the mathematical properties of computer hardware and software.

What are the types of languages in theory of computation?

Grammar Languages Automaton Type-0 Recursively enumerable Turing machine Type-1 Context-sensitive Linear-bounded non-deterministic Turing machine Type-2 Context-free Non-deterministic pushdown automaton Type-3 Regular Finite state automaton

Is a * regular language?

A regular language is

a language that can be expressed with a regular expression

or a deterministic or non-deterministic finite automata or state machine. A language is a set of strings which are made up of characters from a specified alphabet, or set of symbols.

Is English regular language?

Is English a regular language?

No

. The typical proof (as in PtMW, 478-9) uses closure under intersection plus the pumping lemma (pumping theorem). First let’s practice using the pumping lemma some more to show that some languages on the alphabet {a,b} are not regular languages.

Is Python a regular language?

What does that mean, and why aren’t they? Python and Haskell both use indentation-sensitive syntax, so they have to recognize changes in the indentation level as tokens.

How do you prove a language is regular?

To prove a language is regular:

construct a DFA, NFA or RE that recognizes it

. To prove a language is not regular: show that recognizing it requires keeping track of infinite state (hard to be completely convincing in most cases) or use the pumping lemma to get a contradiction.

What is regular and non regular languages?

Example 1 – All strings of length = 2 over {a, b}* i.e. L = {aa, ab, ba, bb}

is regular

. Given an expression of non-regular language, but the value of parameter is bounded by some constant, then the language is regular (means it has kind of finite comparison).

Which type of language is regular expression?


Formal language theory

. Regular expressions describe regular languages in formal language theory. They have the same expressive power as .

Can A Regular Language Be Finite?

4 Answers. A language is regular == A language can be expressed by a == A language can be expressed by a . Your example is indeed a . A finite language is what you would expect it to be, a language

that can be listed in a finite amount of time

.

Can a language be an infinite set?

(An infinite language is a language with

infinitely many strings in

it. {an | n ≥ 0}, {ambn | m, n ≥ 0}, and {a, b}∗ are all infinite .) Lemma 1. If A is an infinite language, then for every natural number n ≥ 0, there exists a string w ∈ A such that |w| > n.

Is regular language accepted by finite automata?

Finite automata can be

used to generate strings

in a regular language.

How many infinite languages are regular?

(1) There are

a countably infinite number

of regular languages. This true because every description of a regular language is of , so there is a countably infinite number of such descriptions. (2) There are an uncountable number of languages. Thus there are more languages than there are regular languages.

Why is finite language regular?

All finite languages are regular; in particular the

empty string language {ε} = Ø* is regular

. Other typical examples include the language consisting of all strings over the alphabet {a, b} which contain an even number of as, or the language consisting of all strings of the form: several as followed by several bs.

Which Cannot be accepted by a regular grammar?

5. Which among the following cannot be accepted by a regular grammar? Explanation:

There exists no finite automata to accept the given language

i.e. 0

n

1

n

. For other options, it is possible to make a dfa or nfa representing the language set.

How do you prove a language is regular?

To prove a language is regular:

construct a DFA, NFA or RE that recognizes it

. To prove a language is not regular: show that recognizing it requires keeping track of infinite state (hard to be completely convincing in most cases) or use the pumping lemma to get a contradiction.

Can a DFA accept an infinite language?

The language accepted by a deterministic finite automata is

infinite if and only if there exists some cycle on some path from which a final state is reachable

. If you minimize your automaton, then there is at most one state from where you cannot reach a final state anymore (a so called sink state).

Is Kleene star infinite?

The Kleene closure is defined to only have .

There are an infinite number of such strings

, just as there are an infinite number of integers. … A string from the Kleene closure can not contain every character from an infinte alphabet.

Is a finite language fo definable?


All finite languages are regular

; in particular the empty string language {ε} = Ø* is regular. Other typical examples include the language consisting of all strings over the alphabet {a, b} which contain an even number of as, or the language consisting of all strings of the form: several as followed by several bs.

What makes a language not regular?

A simple example of a language that is not regular is

the set of strings { a

n

b

n

| n ≥ 0

}. Intuitively, it cannot be recognized with a finite automaton, since a finite automaton has finite memory and it cannot remember the exact number of a’s.

Which grammar is always unambiguous?

Explanation:

Deterministic CFGs

are always unambiguous , and are an important subclass of unambiguous CFGs; there are non-deterministic unambiguous CFGs, however. Explanation: The closure property of a context free grammar

When a string is accepted by a PDA?

In final state acceptability, a PDA accepts a string when,

after reading the entire string, the PDA is in a final state

. From the starting state, we can make moves that end up in a final state with any stack values. The stack values are irrelevant as long as we end up in a final state.

Which of the following can be accepted by a Dpda?

Which of the following can be accepted by a DPDA? Explanation: Theorem:

The language pal of palindromes

over the alphabet {0,1} cannot be accepted by any finite automaton , and it is therefore not regular. Explanation:The possible change in the stack contents is a change in the number of A’s on the stack.

Which language is accepted by DFA?

A language L is accepted by a DFA < Q , , q

0

, , A > , if and only if L = { w |

*

( q

0

, w ) A } . That is, the language accepted by a DFA is the

set of strings

accepted by the DFA.

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