• June 19, 2019

Theory of computation (TOC) (CS) (CS) (CS53) ( CS) Question Bank 1 (old) – View Question Bank 2 (old) – View / Download Question bank. Anna University Department of computer science engg Fifth Semester CS theory of computation (Regulation ) Semester: 5. Third Year CSE(Sem:V) 2 marks Questions and Answers NFA can be used in theory of computation because they are more flexible and easier to use than.

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A special case of FA is Moore machine in which the output depends on the state of the machine. A multi-tape Questiion machine consists of a finite control with k-tape heads and ktapes ; each tape is infinite in both directions.


A sentence is a string of terminal symbols. ID describe the configuration of a PDA at a given instant. The grammar is thus: Find CFG with no useless symbols equivalent to: What is a Diagonalization language Ld? What are the concepts used in UTMs? The Turing machine is equivalent in computing power to the digital computer. Let P,Q be any two computarion languages.

Finite Automata is used witn model regular expression and cannot be used to represent non regular languages. Thus to model a context free language, a Pushdown Automata is used. Gives the substitute a quesyion blank for the first string of two or more blanks in a given line.


NFA or Non Deterministic Finite Automaton is the one in which there exists many paths for a specific input from current state to next state.


The set may be empty,finite or infinite. A language L is recursively enumerable if there is a TM that accepts L and. P n-1 is called the induction hypothesis. A TM can be used as a transducer.

Theory of Computation – TOC – Computer Science- Anna University – Question bank – CS

The pumping lemma can be used to prove a variety of languages are not context free. Any computation that can be done by 2-way infinite tape can also be done by standard TM. A lexical analyzer scans the symbols of a program to locate strings corresponding to identifiers, constants etc, and it has to remember limited amount of information.

Consider the ambiguity problem for CFGs.

A problem whose language is recursive is said to be decidable. In one move, the heads may each move independently left or right or remain stationary. CFL are closed under substitutionhomomorphism.

The move dependent on the input symbol a scanned is:. The questiob has the production P as:. What properties of recursive enumerable seta are not decidable?

The height of the parse tree is the length of the longest path from the root to some leaf. CFL are not closed under intersectioncomplementation. Turing machine can change symbols on its tapewhereas the FA cannot change symbols on tape.


Although the voltages assume infinite set of values,the electronic circuitry is designed so that the voltages orresponding to 0 or 1 are stableand all others adjust to these value. In 2-way infinite tape TM, the tape is infinite in both directions. Let L be a CFL. They are similar to r. What is auestion ordering? Pumping lemma is used to check if a language is regular or not.

Nothe language accepted by non-deterministic Turing machine is same as recursively enumerable language. A function f i1,…ik computed by a Turing machine is queshion a partial recursive function. We can describe TM using:. The regular sets are closed under union, concatenation and Kleene closure. The tape head moves to the rightrepeatedly storing the symbols in the FC and replacing the symbols read from coputation cells to the left. Let L be any CFL.

Tweet Share Share Share Share. This problem is undecidable as there is no algorithm to solve this problem.