Automata Theory and Formal Language

Increasing accuracy, or precision

• Minimizing False Positives

Which among the following is the correct option for the given grammar? G->X111|G1,X->X0|00.

• {0a1b|a=2,b=3}

A set has n elements, then the number of elements in its power set is?

• 2n
• 2 ^ n
• None of the choices
• 2n-1

A set of accepting states (F ∈ Q).

• F

Checking whether there is a matching parenthesis in a computer code can be done by a ______________.

• regular expression
• automatically by a very patient debugger
• context-free language
• context-free grammar

A PDA is already in its accept state if:

• and only if it is both in the final state and the stack is empty
• none of the given choices
• it is either in the final state or the stack is empty
• it has no more input to process

The recursive inference procedure determines that string w is in the language of the variable A, A being the starting variable.

• TRUE

For a regular expression 'a', we can construct the following FA:

• TRUE

Context-free grammars are more expressive than finite automata; if a language L is by a finite automata then L can be blank by a context-free grammar.

• Accepted

NP-Hard problems are problems that are...

• Easy (they are called hard so that computer programmers can be paid more)
• intractable
• none of the choices
• hard

Any set that represents the value of the Regular Expression is called a Property set.

• FALSE

Noam Chomsky gave a mathematical model in which is effective for writing computer languages.

• 1956

Leibniz introduced binary notation of calculation.

• FALSE

* Starts from tree leaves. It proceeds upward to the root which is the starting symbol S.

• Bottom-Up Approach

Which of the following statements are correct for a concept called inherent ambiguity in CFL?

• Every CFG for L is ambiguous

In Allan M. Turing proposed the Turing machine as a model of "any possible computation".

• 1936

A finite set of input symbols.

• Σ

A ⊂ B is read as ________________.

• A is less than B
• A is a subset of B
• B is a subset of A
• A is a proper subset of B

Given the productions S → αXβ, X → a, ___________________.

• X is not reachable nor generating
• X is reachable but not generating
• X is useful
• X is not reachable but is generating

A general purpose, programmable, information processor with input and output.

• computer

Which among the following cannot be accepted by a regular grammar?

• L is a set of 0n1n

According to what concept is CFL a superset of RL?

• Chomsky Hierarchy
• Chomsky Normal Form
• Backus-Naur Form
• None of the given choices

The union of sets A and B is expressed as?

• A U B
• A - B
• A / B
• A x B

If A has m elements and B has n elements, then A x B has elements?

• m - n
• m + n
• 2n
• m x n

A finite set of states

• Q

In mathematical notation, the symbol → means...

• implication
• an element of
• not an element of
• assignment statement

The first counting machine developed 5000 years ago in the Middle East.

• Abacus

Language may be derived from other strings using the productions in a grammar.

• FALSE

An initial state q0 ∈ Q

• q0

A formal language is a set of strings, each string composed of symbols from a finite set called

• alphabet

JASON can generally be parsed by ______________.

• A C parser
• A CFG
• A Java parser
• A RE

The string "0000111" is accepted by _____________.

• the CFG S → 0S1 | A, A → A1 | ε
• the CFG S → 1S0 | A, A → A0 | ε
• the CFG S → 0S1 | A, A → 0A | ε
• none of the choices

A DFA is represented by digraphs called.

• State Diagram

A set of rules, P: N → (N U T)*, it does have any right context or left context.

• P

All functions are relations

• True
• False

NFA means:

• Nondeterministic Finite Automaton
• Nondeterministic Final Automaton
• Nondifferentiable Final Automaton
• Nondifferential Finite Automaton

“If H then ” is also the same as saying _______.

• “If H then C else do nothing”
• “If C then H”
• “If H then C else {}”
• “C if H”

A DPDA is a PDA in which.

• No state p has two outgoing transitions

“Whenever H holds, C follows” can also be said as _______.

• H → ε and ε → C
• H → C
• C → H
• ε → H and C → ε

Are ambiguous grammar context free?

• TRUE

A right-most derivation of a sentential form is one in which rules transforming the are always applied.

• Context

The string abe is accepted by this regular expression.

• a*b*c*a*d*
• a+b+c+d+e*
• a*b*c*a*d*e+
• a+b+c+d+

The intersection of sets A and B is expressed as _________________.

• A - B
• A / B
• A x B
• A ∩ B

challenged the mathematical community to find an infallible, mechanical method for constructing and checking truth of mathematical statements.

• David Hilbert

An order rooted tree that graphically represents the semantic information a string derived from a context-free grammar.

• Derivation tree

The transition a Push down automaton makes it additionally dependent upon the _____.

• stack

In words, H → C means…

• Whenever H holds, C follows
• Whenever H does not follow, C does not follow either
• Whenever H is true, then it becomes C
• Whenever H, then it becomes C

An alphabet is any finite set of symbols.

• TRUE

“C if H” is also the same as saying _______.

• “If H then ”
• “If C then H”
• “If H then C else {}”
• “If H then C else do nothing”

Unconsumed input

• w

It process information in their efforts to eat, survive, and reproduce.

• Living Organisms

Unconsumed input.

• w

What is a language?

• A way to communicate with other humans
• A collection of finite-length sentences that were constructed from a finite set of symbols
• A code that you use when writing a computer program
• English, Filipino and Valyrian are examples of a language

The difference between DFA and NFA

• DFA is where you get your passport while NFA is where you get your cheap rice
• NFA can exist in only one state at a given time while DFA can exist in multiple states
• DFA can exist in only one state at a given time while NFA can exist in multiple states
• DFA is also an NFA

The first mechanical calculator using gears for calculation developed in 1642.

• Pascaline

A language accepted by Deterministic Push down automata is closed under which of the following?

• complement

A language is regular if and only if.

• Accepted by DFA

A set of final state/states of Q (F⊆Q).

• F

If a problem can be shown that it belongs to the class of recursively enumerable languages then ______________________.

• It may be solved by any TM
• It may be solved by a special RE
• It may be solved by a special TM
• It may be solved by any RE

Any production rule in the form A → B where A, B ∈ Non-terminal is called unit production.

• Unit Production

The initial stack top symbol (I ∈ S)

• I

A set of strings of a's and b's of any length including the null string. So L= { ε, a, b, aa , ab , bb , ba, aaa.......}, the regular expression is.

• (a+b)*

Turing hypothesis believed that a function is said to be computable if and only if it can be computed by a Turing machine.

• FALSE

Finite Automata all regular languages and only regular languages.

• Accept

A good regular expression for any valid whole number is ______________.

• [0-9]*
• [0-9]*[0-9]*
• [0-9]+
• [0-9]+[0-9]*

Every set is a / an ________________ of itself.

• None of the choices
• Complement
• Proper Subset
• Improper Subset

Regular expression Φ* is equivalent to

• ϵ

The string acde is accepted by this regular expression.

• a+b+c+d+
• a+b+c+d+e*
• a*b*c*a*d*
• a*b*c*a*d*e+

A finite set of states.

• Q

{Q, Σ, q0, F, δ, Q × Σ → Q} is…

• An NFA
• Either DFA or NFA
• There is no such tuple
• A DFA

It refers to the measure of the number of times the tape moves when the machine is initialized for some input symbols and the space complexity is the number of cells of the tape written.

• Time Complexity

Regular expression Φ* is equivalent to.

• ϵ

A good regular expression for any valid real number using engineering notation is ______________.

• [0-9]+[0-9]*[(E|e)[0-9]+]
• [0-9]*
• [0-9]+[0-9]*[(E|e|∈)[0-9]+]
• [0-9]+

In the Chomsky Hierarchy:

• Regular Language ⊂ Context-sensitive Language
• Regular Language ⊃ Context-sensitive Language
• Regular Language| • |Context-sensitive Language
• Regular Language = Context-sensitive Language

Empty set is a/an ________________.

• Infinite set
• Finite set
• Invalid set
• None of the choices

An initial state q0 ∈ Q.

• q0

A grammar G is ambiguous if there is a word w Î L(G) having are least two different parse trees.

• TRUE

A DFA is defined ____________________.

• as Department of Finite Automaton
• by a 5-tuple which is {Q, Σ, q0, F, δ}
• by a 6-tuple which is {Q, Σ, q0, F, δ, Q × Σ → Q}
• as Department of Foreign Affairs

Which one is the answer?

• Computer

Set of final or accepting states

• F

* Starts with the starting symbol S. It goes down to tree leaves using productions.

• Top-Down Approach

If A = {3, 4, 6, 8} and

• { 4,6}

A nested if-then statement is one of these:

• If w then x if y then z
• If w if x then y then z
• If w then if x then y else z
• All of the choices are examples of nestedness

A sub-tree of a derivation tree/parse tree such that either all of its children are in the sub-tree or none of them are in the

• Partial Derivation Tree, Sub-Tree

Is a finite set of symbols called the alphabet.

• Σ

Number of states require to accept string ends with 10.

• 3

The cardinality of the union of two disjoint sets is less than the sum of the cardinality of the given sets.

• True
• False

It starts from the top with the start-symbol and derives a string using a parse tree.

• Top-Down Parser

A PDA machine configuration (p, w, y) can be ly represented as ____________

• current state, unprocessed input, stack content

Any production rule in the form A → B where A, B ∈ Non-terminal is called.

• Unit Production

It generate context-free languages. The productions must be in the form A → γ

• Type-2 grammars

The algebraic law of regular expression described by φE = φ = Eφ is _______________.

• Annihilator
• Associative
• Commutative
• Identity

S → aAb, aA →aaAb, A→ε

• P

|-* is the _____ closure of |-

• transitive and reflexive

The stack content

• s

The stack contents

• s

If R ={(1,1),(2,3),(4,5)}, then the Range of the function is?

• Range R {1,1,4,5}
• Range R {1,2,5}
• Range R = {2,3,4,5}
• Range R = {1,3,5}

Start symbol, S ∈ N

• S

A of a derivation is a tree in which each internal node is labeled with a nonterminal.

• Parse Tree

There are 5 tuples in finite state machine.

• TRUE

Some graphs contain cycles.

• True
• False

In _____ Allan M. Turing proposed the Turing machine as a model of "any possible computation".

• 1936

Finite set of states.

• Q

A PDA machine configuration (p, w, y) can be correctly represented as ____________ .

• current state, unprocessed input, stack content

An indirect way of building a CFG is to _____________

• build a regular expression and then construct a PDA from it, and then construct CDF from it
• You can only build a CFG directly
• build a PDA and then construct a CFG from it
• none of the given choices

A 2-Tape Turing Machine ___________________.

• can infer that recursive languages are closed under union
• can show that recursive languages are closed under union
• has two outputs
• has two inputs

If A = {5,6,7} and B = {7,8,9} then A U B is equal to:

• {5,6,7}
• None of the choices
• {7,8,9}
• {5,6,7,8,9}

What can be said about undecidable problems?

• They are definitely recursive
• They are surely iterative
• They are not recursive
• They are not iterative

A good regular expression of a person's name is ______________.

• None of the given choices
• [A-Z][a-z]+
• [A-Z][a-z]?
• [A-Z][a-z]*

What can not be said about CFLs?

• It is closed under ~
• It is closed under —
• All of the given choices
• It is closed under ∩

Connected graphs have components.

• True
• False

Labeled by a terminal symbol or ε.

• Leaves

An automaton that produces outputs based on current input and/or previous state is called.

• Transducer

What are strings?

• A string is an infinite area of symbols chosen from Σ
• A string is a finite sequence of symbols chosen from Σ
• A string is a finite area of symbols chosen from Σ
• A string is an infinite sequence of symbols chosen from Σ

All relations are functions

• True
• False

Non-terminal symbols

• S & A

The tape head is positioned at one of the tape cells for scanning the input symbol from the input tape and initially the tape head points at the left most cell of the input tape.

• TRUE

What is a grammar?

• How a sentence should be constructed to avoid syntax error
• "Them cowboys is dumb!" is an example of a wrong grammar
• "We ain't gonna make mistakes" is an example of correct grammar
• A device that enumerates the sentences of a language

The unconsumed input

• w

If R = {(1,1),(2,3),(4,5)}, then domain of the function is?

• Dom R = {2,3,4,5}
• Dom R = {1,2,4}
• Dom R {1,3,5}
• Dom R {1,1,4,5}

A stack symbols

• Σ

A may or may not read an input symbol, but it has to read the top of the stack in every transition

• PDA

The language L contains all strings over the alphabet {a,b} that begin with and end with

• a,b

The __________ of a Turing machine depends on the current state of finite control and the tape symbol present in the input tape.

• single move

A set of terminals where N ∩ T = NULL.

• T

Which of the following Set Operations produces the set that contains everything that is in Set A and in Set B?

• Complement
• union
• Intersection
• Set Difference

Finite set of input alphabets

• Σ

Labeled by the start symbol.

• Root Vertex

Terminal symbols

• a & b

An algorithms to shampoo your hair.

• rinse, lather, repeat

Which of the following statement is false in context of tree terminology?

• Root with no children is called a leaf

The relationship between recursive and recursively enumerable languages is ________________.

• ∈
• ⊂
• ∉
• ⊃

The string aaaabbbccaaad is accepted by this regular expression.

• a+b+c+d+
• a*b*c*a*d*e+
• a*b*c*a*d*
• a+b+c+d+e*

Increasing coverage, or recall.

• Minimizing False Negatives

Increasing accuracy, or precision.

• Minimizing False Positives

Given the language L = {ε}, is L empty?

• none of the given choices
• Definitely, because ε is an empty symbol
• No, because the language has an empty symbol
• You can't say

A Finite Automaton with null moves (FA-ε) does transit not only after giving input from the alphabet set but also without any input symbol. This transition without input is called a.

• Null Move

How many sets belong to the power set of A = {a,b,c,d}?

• 4
• 8
• 7
• 16

Which among the following is the option for the given grammar? G->X111|G1,X->X0|00

• {0a1b|a=2,b=3}

A string is accepted by a, iff the DFA/NDFA starting at the initial state ends in an after reading the string.

• NDFA

What is automata theory?

• To answer the fundamental questions in computer science
• All of the choices
• To find out if a problem is computable
• Study of abstract computing devices or machines

Context-free grammars are more expressive than finite automata; if a language L is by a finite automata then L can be by a context-free grammar.

• Accepted, Ignored

What can be said about CFLs?

• It is closed under ~
• It is closed under ∩
• All of the given choices
• It is closed under •

T generate recursively enumerable languages. The productions have no restrictions and phase structure grammar including all formal grammars.

• Type-0 grammars

A _____ may or may not read an input symbol, but it has to read the top of the stack in every transition

• PDA

Context-free grammars are more expressive than finite automata; if a language L is _____ by a finite automata then L can be _______ by a context-free grammar.

• accepted, generated

A' will contain how many elements from the original set A?

Labeled by a non-terminal symbol.

• Vertex

The power set of a given set does not contain the set itself.

• True
• False

It is a unary operator on a set of symbols or strings, that gives the infinite set of all possible strings of all possible lengths.

• Σ *

The empty set is always a subset of any set.

• True
• False

Context Free Languages is closed under intersection.

• False
• True

Is the initial state from where any input is processed (q0 ∈ Q).

• q0

A set on non-terminal symbols.

• S & A

If we can successfully and correctly stimulate a TM with storage by two standard TMs, then ______________________.

• None of the choices
• we have already shown that the TM with storage is at least twice as powerful as one standard TM
• we have already shown that the two are equivalent
• we have already shown that one standard TM is half as powerful as the TM with storage

A PDA accepts a string when, after reading the entire string, the PDA is in a final state.

• TRUE

A regular expression consisting of a finite set of grammar rules is a quadruple.

• FALSE

Elimination of productions and symbols is called simplification of CFGs. Simplification essentially comprises of the following steps:

• Reduction of CFG

An English like abbreviations representing elementary computer operations.

• Assembly Language

Having the initial state as a final state, give the deterministic finite state automaton that accepts the regular expression.

• ((a.b)+c)*

The commutativity property of set operations states that the union of any set with same set is the set itself.

• True
• False

IT generate recursively enumerable languages. The productions have no restrictions and phase structure grammar including all formal grammars.

• Type-0 grammars

A Finite Automaton with null moves (FA-ε) does transit not only after giving input from the alphabet set but also without any input symbol. This transition without input is called a

• Null Move

Let w = 100011, is w a member of a language of string with equal number of 0s and 1s?

• Yes, because the number of 1s is the same as the number of 0s, which is 3
• It is hard to ascertain because 100011 is 35 in decimal, which is an odd number
• No, because even if the symbols 1 and 0 are of the same number, they are not palindromic
• This is an NP-hard problem

Circuits in graphs are always simple paths.

• True
• False

A may or may not read an input symbol, but it has to read the top of the stack in every transition.

• PDA

Blank symbol

• Δ

are parameterized statement, they are true or false depending on the values of their parameters.

• predicates

A set of accepting states (F ∈ Q)

• F

Which of the following is a not a part of 5-tuple finite automata?

• Output Alphabet

If L1 and L2 are regular sets then intersection of these two will be.

• Regular

Finite set of input alphabets.

• Σ

A Moore machine can be described by a tuple.

• 6

An example string w of a language L characterized by equal number of As and Bs is _______________.

• BABAE
• ABABA
• ABBBAA
• ALIBABA

The body of a production in CFG is composed of:

• a string of terminals only
• none of the choices given because a CFG production does not have a body
• a string of non-terminals only
• a string of terminals and non-terminals

The difference between regular expressions and finite automata is _____________.

• that automata are more program syntax-like while regular expression are more machine-like
• |regular expression| - |finite automata| = |Turing Machine| because you can only get the difference by computing for their respective lengths
• that regular expressions are more program syntax-like while automata are more machine-like
• {regular expression} - {finite automata} = { } because they are sets and they are equivalent

Regular sets are closed under union,concatenation and kleene closure.

• TRUE

Finite set of states

• Q

The theory of formal languages finds its applicability extensively in the fields of Computer Science. gave a mathematical model of grammar in which is effective for writing computer languages.

• Noam Chomsky, 1956

Which of the following ways can be done to simplify a CFG?

• Eliminate symbols that are not useful
• Eliminate the ε symbol
• Eliminate productions of the form A → B

How many rational and irrational numbers are possible between 0 and 1?

• 0
• Infinite
• Finite
• 1

A new symbol is added at the top.

• Push

A transition function: Q × (Σ∪{ε}) × S × Q × S*.

• δ

Identify the modeling recognition of the word "then"

• Start State

Recursive : TM that always halt = ________________ : TM that may or may not halt

• iterative
• recursively enumerable
• none of the choices given
• iteratively enumerable

A formal language is a set of strings, each string composed of symbols from a finite set called.

• Alphabet

Every context free grammar can be transformed into an equvalent non deterministic push down automata.

• TRUE

The start symbol.

• S

What is a Universal TM?

• a TM that stimulates another TM
• A TM that can solve all problems
• A TM that can solve all undecidable problems
• a Universal TM does not exist

The unconsumed input.

• w

Transition function

• δ

What is the final result after converting the following NFA-ε to NFA without Null move.

• What is the final result after converting the following NFA-ε to NFA without Null move.

The number of elements in the set for the Language L={xϵ(∑r) *|length if x is at most 2} and ∑={0,1} is

• 7

Is the transition function where δ: Q × Σ → Q.

• δ

Production Rule: aAb->agb belongs to which of the following category?

• Context Sensitive Language

A DPDA is a PDA in which

• No state p has two outgoing transitions

__ is the initial state from where any input is processed (q0 ∈ Q).

• q0

Is a set of final state/states of Q (F ⊆ Q).

• F

If A = {0,2) and B = {1,3), then Cartesian product is?

• none of the choices
• A x B not equal B x A
• A x B = B x A
• is not possible

If we can successfully and ly stimulate a TM with storage by two standard TMs, then ______________________

• we have already shown that the two are equivalent

The CFG "S → (S) | SS | ε" accepts:

• the string "<<>><><<>>"
• the string "(((((((((())))))))))"
• the string "((()))(())(())"
• the string "{} { {} } [[]]"

Empty string

• Σ

Who is the father of modern computer?

• Charles Babbage

Is used to derive a string using the production rules of a grammar.

• Production

A finite number of states.

• Q

Starting state

• q0

If A →* ε, then we can say that:

• A is not generating
• A is not reachable
• A is nullable
• A is not generally useful

According to the 5-tuple representation i.e. FA= {Q, ∑, δ, q, F} Statement 1: q ϵ Q'; Statement 2: FϵQ

• Statement 1 is false, Statement 2 is true

For every CFL, G, there exists a PDA M such that L(G) = L(M) and vice versa

• TRUE

The entity which generate Language is termed as:

• Grammar

Global Positioning System (GPS) calculates latitude and longitude from satellite signals.

• True

All trees contain loops.

• True
• False

Is to be applied to show that certain languages are not regular. It should never be used to show a language is regular.

• Pumping Lemma

The stack contents.

• s

The initial state (q0 ∈ Q)

• q0

The following are phases of C++ Programs except

• Process

The _____ of two sets A and B is the set containing those elements which are elements of A or elements of B.

• union

A DFA can remember a finite amount of information, but a can remember an infinite amount of information.

• PDA

The complement of an infinite language is necessarily finite.

• FALSE

Which of the following statements are for a concept called inherent ambiguity in CFL?

• Every CFG for L is ambiguous

__ is the transition function where δ: Q × Σ → Q.

• δ

The transition a Push down automaton makes it additionally dependent upon the

• Stack

Which of the following statements is true about NPDA, DPDA, and RL?

• RL • DPDA • NPDA
• RL* • DPDA* • NPDA*
• RL ⊃ DPDA ⊃ NPDA
• RL ⊂ DPDA ⊂ NPDA

What is an undecidable problem?

• When a TM cannot make a decision on an instance of the problem
• When a CFG cannot make a decision on an instance of the problem
• When a PDA cannot make a decision on an instance of the problem
• When a RE cannot make a decision on an instance of the problem

Z2 uses electricity to convey letters and transmit information quickly in 1844.

• TRUE

A compact textual representation of a set of strings representing a language.

• Regular Expressions

The minimum number of states required to recognize an octal number divisible by 3 are/is.

• 3

If Σ2 is {00, 01, 10, 11}, then Σ =

• {0, 1}
• {false, true}
• {true, false}
• {F, T}

For every CFL, G, there exists a PDA M such that L(G) = L(M) and vice versa.

• TRUE

What kind of languages does a TM decide?

• regular expression
• context-sensitive
• recursively enumerable
• context-free

It starts from the bottom with the string and comes to the start symbol using a parse tree.

• Bottom-Up Parser

Given that the language L = {ε}, is L empty?

• None of the given choices
• No, because the language has an empty symbol
• Definitely, because ε is an empty symbol
• This is a case of apples and oranges, you really can't compare!

Computers are general purpose because they can perform many different tasks.

• TRUE

Which among the following is not a part of the Context free grammar tuple?

• End SymbolCorre

The symbol used for the empty string is ____________.

• ε
• φ
• a blank
• ψ

What cannot be said about automata theory?

• None of the choices
• Automata theory is the study of abstract computing devices or machines
• Automata theory is used to find out if a problem is computable
• Automata theory answers the fundamental questions in computer science

Which of the following will not be accepted by the following DFA?

• ababaabaa

Set of final or accepting states.

• F

A finite number of states

• Q

A conceptual design for a machine consisting of a Mill, Store, Printer, and Readers.

• Analytic Engine

IT generate recursively enumerable languages. The productions have no restrictions and phase structure grammar including all formal grammars. They generate the languages that are recognized by a Turing machine.

• Type-0 grammars

Noam Chomsky gave a mathematical model in ___ which is effective for writing computer languages.

• 1956

For every pair of regular expressions R and S, the languages denoted by R(SR)* and (RS)*R are the same.

• TRUE

If L1 and L2 are regular sets then intersection of these two will be

• Regular

A DFA can remember a finite amount of information, but a ____ can remember an infinite amount of information.

• PDA

Set of all tape symbols

• Γ

The entity which generate Language is termed as regular languages.

• FALSE

Number of final state require to accept in minimal finite automata.

• None of the mentioned

For the given Regular expression, the minimum number of terminals required to derive its grammar (011+1)*(01)* is

• 3,6,2,5,4

__ is a set of final state/states of Q (F ⊆ Q).

• F

The initial stack top symbol (I ∈ S).

• I

A PDA machine configuration (p, w, y) can be correctly represented as.

• Current state, Unprocessed input, Stack content

The PDA has infinite memory and access in _____ order and the finite automata has ____ memory.

• LIFO, finite

A pushdown automaton is a way to implement a context-free grammar in a similar way to design DFA for a regular grammar.

• TRUE

If L is recursively enumerable then ________________.

• none of the choices given is correct
• L is also recursively enumerable
• L is definitely not recursively enumerable
• L may not be recursively enumerable

A transition function: Q × (Σ∪{ε}) × S × Q × S*

• δ

A __________ of a derivation is a tree in which each internal node is labeled with a nonterminal.

• parse tree

______ is used to derive a string using the production rules of a grammar.

• Parsing

Who is the father of modern computer science?

• Noam Chomsky
• Alan Turing
• Steve Jobs
• Bill Gates

__ is a finite set of states.

• Q

A set of strings of a's and b's of any length including the null string. So L= { ε, a, b, aa , ab , bb , ba, aaa.......}, the regular

• (a+b)*

Computer science has roots in two fields :

• Mathematics

Noam Chomsky gave a mathematical model in _______ which is effective for writing computer languages.

• 1956

|-* is the closure of |-

• Transitive and Reflexive

One of the first programmable electronic computers in 1945.

• ENIAC

__ is a finite set of symbols called the alphabet.

• Σ

The basic model of a Turing machine consists of _______ and _______ , in which the finite control has finite set of states and the transition between the states.

• finite control, input tape

The algebraic law of regular expression described by E + E = E is _____________.

• Annihilator
• Identity
• Additive idempotent
• Idempotent

A parsing that starts from the top with the start-symbol and derives a string using a parsetree.

• top-down parser

Let the class of language accepted by finite state machine be L1 and the class of languages represented by regular expressions be L2 then.

• L1=L2

An ε-NFA with a stack is also regarded as:

• A CFG
• A FSA
• A PDA
• A RE

The top symbol is read and removed.

• Pop

Is a finite set of states.

• Q

A - B will contain elements in?

• B not in A
• A not in B
• Neither A nor B
• Both A and B

For bottom-up parsing, a PDA has the following four types of transitions:

• Push the current input symbol into the stack., Replace the right‑hand side of a production at the top of the stack with its left‑hand side. , If the top of the stack element matches with the current input symbol, pop it. , If the input string is fully read and only if the start symbol 'S' remains in the stack, pop it and go to the final state .

In ____ Allan M. Turing proposed the Turing machine as a model of "any possible computation".

• 1936

A transition function δ : Q × (Σ ∪ {ε}) → 2Q.

• δ

* Starts from tree leaves. It proceeds upward to the root which is the starting symbol S

• bottom-up approach

A symbol X is reachable _________________________.

• if S → aXβ
• if X →* w, for some w ∈ Σ
• if X → w, for some w ∈ Σ
• if S →* aXβ

A pushdown automata can be regarded as:

• a ε-NFA with a stack
• a DFA with a FILO queue
• a NFA with a stack
• a DFA with FIFO queue

What is an ε-NFA?

• It is a DFA where all transitions are ε-transitions
• It is an NFA where all transitions are ε-transitions
• It is a DFA with at least one explicit ε-transition defined
• It is an NFA with at least one explicit ε-transition defined

The of a Turing machine depends on the current state of finite control and the tape symbol present in the input tape.

• Single Move

What concept did Alan Turing introduce?

• The concept of programs and programmabilities of problems
• The concept of decidability
• The concept of functions and relations
• The concept of undecidability