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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Turing machine is a simple mathematical model of a computer. TM has unlimited and unrestricted memory and is a much more accurate model of a general purpose computer. So we require a PDA ,a machine that can count without limit. Banj problem is undecidable as there is no algorithm to solve this problem.

Find out the CFL. When is a trivial property? All combinations with the pattern Is it true that the language accepted by a non-deterministic Turing machine is different computtaion recursively enumerable language? Xk respectively then A X1X2…. Each variable and each terminal of G appears in the derivation of some word in L. The label of the root may not be the start symbol of the grammar.

It can reject the string by entering witb state. It can enter an infinite loop so that it never halts.

In one wuestion ,TM depending upon the symbol scanned by the tape head and state of the finite control:. A k-head TM has some k heads.

CS theory of Computation easy way to pass,tips to clear TOC | 5 STAR NOTES

In a multi-tape TM ,one tape acts as an output tape, on which a symbol, once written can never be changed and whose tape head never moves left. A regular expression is a string that describes the whole set of strings according to certain syntax rules.


The pumping lemma can be used to prove a variety of languages are not context free. The input string is accepted by the PDA if:. TOC suggests various abstract models of computation, represented mathematically. Decidable problems have an. In one move, the heads may each move independently left or right or remain stationary. L is recursively enumerable iff satisfies the following properties:.

All common arithmetic functions on integers such as multiplicationn! V and T are disjoint. What are the possibilities of a TM when processing an input string?

It has an infinite tape divided into cells ,each cell holding one symbol. Enumerable means that the strings in the language can be enumerated by the TM.

Q s a finite set of states. The grammar is thus: Apart from the halt statea given TM is total.


Finally the productions are: On a single move depending on the state of finite control and symbol scanned by each of tape heads ,the machine can change state print a new symbol on each cells scanned by tape head, move each of its tape theorh independently one cell to the left or right or remain stationary. If L is an infinite language in ,then there is a finite subset of L in. The Turing machine is equivalent in computing power to the digital computer.

P n-1 is called the induction hypothesis. A TM can be used as a transducer. What is a Diagonalization language Ld?


Thus to model a context free language, a Pushdown Automata is used. We can describe TM using:. This hierarchy is called as Chomsky Hierarchy. M is a DFSM that.

Hence useful productions are: What is canonical ordering?

What properties of recursive enumerable seta are not decidable? What are the concepts used in UTMs? Grammar or regular expression Generative approach Automaton Recognition approach. What are the three ways to simplify qudstion context free grammar?

CS Theory of computation RJ edition 2 and 16 marks with answers -Unit wise

The notion of computable function can be identified with the class of partial recursive functions is known as Church-hypothesis or Church-Turing thesis. A function f i1,…ik computed by a Turing machine is called a partial recursive function. The grammar has the production P as:. Xk must be in P. Hence B is useless symbol and remove B from all productions. A multi-tape Turing machine consists of a finite control with k-tape heads and ktapes ; each tape is infinite in both directions.

Depending on the state and symbol scannedthe device changes stateprints a new symbol and moves its tapehead in one of the 2k directions, either positively or negatively ,along one of the k-axes. Pumping lemma is used to check if a language is regular or not. What is the crucial assumptions for encoding a TM?