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Recent questions tagged proof
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211
Peter Linz Edition 5 Exercise 12.3 Question 3 (Page No. 317)
Show that for $|\Sigma| = 1$, the Post correspondence problem is decidable, that is, there is an algorithm that can decide whether or not $(A, B)$ has a $\text{PC}$ solution for any given $(A, B)$ on a single-letter alphabet.
Show that for $|\Sigma| = 1$, the Post correspondence problem is decidable, that is, there is an algorithm that can decide whether or not $(A, B)$ has a $\text{PC}$ solut...
Rishi yadav
215
views
Rishi yadav
asked
Mar 16, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
212
Peter Linz Edition 5 Exercise 12.3 Question 2 (Page No. 317)
$\text{Theorem}:$ Let $G = (V, T, S, P )$ be an unrestricted grammar, with w any string in $T^+$. Let $(A, B)$ be the correspondence pair constructed from $G$ and $w$ be the process exhibited in Figure. Then the ... string $F$ as $v_1$. The order of the rest of the strings is immaterial. Provide the details of the proof of the Theorem.
$\text{Theorem}:$ Let $G = (V, T, S, P )$ be an unrestricted grammar, with w any string in $T^+$. Let $(A, B)$ be the correspondence pair constructed from $G$ and $w$ be ...
Rishi yadav
158
views
Rishi yadav
asked
Mar 16, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
213
Peter Linz Edition 5 Exercise 12.3 Question 1 (Page No. 317)
Let $A = \{001, 0011, 11, 101\}$ and $B = \{01, 111, 111, 010\}$. Does the pair $(A, B)$ have a PC solution$?$ Does it have an MPC solution$?$
Let $A = \{001, 0011, 11, 101\}$ and $B = \{01, 111, 111, 010\}$. Does the pair $(A, B)$ have a PC solution$?$ Does it have an MPC solution$?$
Rishi yadav
228
views
Rishi yadav
asked
Mar 16, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
214
Peter Linz Edition 5 Exercise 12.2 Question 8 (Page No. 311)
For an unrestricted grammar $G$, show that the question $“Is \space L(G) = L(G)^*?”$ is undecidable. Argue $\text(a)$ from Rice’s theorem and $\text(b)$ from first principles.
For an unrestricted grammar $G$, show that the question $“Is \space L(G) = L(G)^*?”$ is undecidable. Argue $\text(a)$ from Rice’s theorem and $\text(b)$ from first ...
Rishi yadav
203
views
Rishi yadav
asked
Mar 16, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
215
Peter Linz Edition 5 Exercise 12.2 Question 7 (Page No. 311)
Let $G_1$ be an unrestricted grammar, and $G_2$ any regular grammar. Show that the problem $L(G_1) \space\cap L(G_2) = \phi $ is undecidable for any fixed $G_2,$ as long as $L(G_2)$ is not empty.
Let $G_1$ be an unrestricted grammar, and $G_2$ any regular grammar. Show that the problem $L(G_1) \spa...
Rishi yadav
181
views
Rishi yadav
asked
Mar 16, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
216
Peter Linz Edition 5 Exercise 12.2 Question 6 (Page No. 311)
Let $G_1$ be an unrestricted grammar, and $G_2$ any regular grammar. Show that the problem $L(G_1) \space\cap L(G_2) = \phi $ is undecidable.
Let $G_1$ be an unrestricted grammar, and $G_2$ any regular grammar. Show that the problem $L(G_1) \space\ca...
Rishi yadav
206
views
Rishi yadav
asked
Mar 16, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
217
Peter Linz Edition 5 Exercise 12.2 Question 5 (Page No. 311)
Let $G$ be an unrestricted grammar. Does there exist an algorithm for determining whether or not $L(G) = L(G)^R$?$
Let $G$ be an unrestricted grammar. Does there exist an algorithm for determining whether or not $L(G) = L(G)^R$$?$
Rishi yadav
781
views
Rishi yadav
asked
Mar 16, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
218
Peter Linz Edition 5 Exercise 12.2 Question 4 (Page No. 311)
Let $G$ be an unrestricted grammar. Does there exist an algorithm for determining whether or not $L(G)^R$ is recursive enumerable$?$
Let $G$ be an unrestricted grammar. Does there exist an algorithm for determining whether or not $L(G)^R$ is recursive enumerable$?$
Rishi yadav
300
views
Rishi yadav
asked
Mar 16, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
219
Peter Linz Edition 5 Exercise 12.2 Question 3 (Page No. 311)
Let $M_1$ and $M_2$ be arbitrary Turing machines. Show that the problem $“L(M_1)\subseteq L(M_2)”$ is undecidable.
Let $M_1$ and $M_2$ be arbitrary Turing machines. Show that the problem $“L(M_1)\subseteq L(M_2)”$ is undecidable.
Rishi yadav
229
views
Rishi yadav
asked
Mar 16, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
220
Peter Linz Edition 5 Exercise 12.2 Question 2 (Page No. 311)
Show that the two problems mentioned at the end of the preceding section, namely $\text(a)$ $L(M)$ contains any string of length five, $\text(b)$ $L(M)$ is regular, are undecidable.
Show that the two problems mentioned at the end of the preceding section, namely$\text(a)$ $L(M)$ contains any string of length five,$\text(b)$ $L(M)$ is regular,are unde...
Rishi yadav
213
views
Rishi yadav
asked
Mar 16, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
221
Peter Linz Edition 5 Exercise 12.2 Question 1 (Page No. 311)
$\text{Theorem}:$ Let $M$ be any Turing machine. Then the question of whether or not $L(M)$ is finite is undecidable. Show in detail how the machine $\widehat{M}$ in $\text{Theorem}$ is constructed.
$\text{Theorem}:$ Let $M$ be any Turing machine. Then the question of whether or not $L(M)$ is finite is undecidable.Show in detail how the machine $\widehat{M}$ in $\tex...
Rishi yadav
176
views
Rishi yadav
asked
Mar 16, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
222
Peter Linz Edition 5 Exercise 12.1 Question 16 (Page No. 308)
Determine whether or not the following statements is true: Any problem whose domain is finite is decidable.
Determine whether or not the following statements is true: Any problem whose domain is finite is decidable.
Rishi yadav
197
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
223
Peter Linz Edition 5 Exercise 12.1 Question 15 (Page No. 308)
Let $\Gamma = \{0,1,\square\}$ and let $b(n)$ be the maximum number of tape cells examined by any $n-$state Turing machine that halts when started with a blank tape. Show that $b(n)$ is not computable.
Let $\Gamma = \{0,1,\square\}$ and let $b(n)$ be the maximum number of tape cells examined by any $n-$state Turing machine that halts when started with a blank tape. Show...
Rishi yadav
149
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
224
Peter Linz Edition 5 Exercise 12.1 Question 14 (Page No. 308)
Consider the set of all $n-$state Turing machines with tape alphabet $\Gamma = \{0,1,\square\}$. Give an expression for $m(n)$, the number of distinct Turing machines with this $\Gamma$.
Consider the set of all $n-$state Turing machines with tape alphabet $\Gamma = \{0,1,\square\}$. Give an expression for $m(n)$, the number of distinct Turing machines wit...
Rishi yadav
156
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
1
votes
1
answer
225
Peter Linz Edition 5 Exercise 12.1 Question 13 (Page No. 308)
Let $B$ be the set of all Turing machines that halt when started with a blank tape. Show that this set is recursively enumerable, but not recursive.
Let $B$ be the set of all Turing machines that halt when started with a blank tape. Show that this set is recursively enumerable, but not recursive.
Rishi yadav
366
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
226
Peter Linz Edition 5 Exercise 12.1 Question 12 (Page No. 308)
Show that the problem of determining whether a Turing machine halts on any input is undecidable.
Show that the problem of determining whether a Turing machine halts on any input is undecidable.
Rishi yadav
144
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
227
Peter Linz Edition 5 Exercise 12.1 Question 10 (Page No. 308)
Let $M$ be any Turing machine and $x$ and $y$ two possible instantaneous descriptions of it. Show that the problem of determining whether or not $x \vdash^{*}_M y$ is undecidable.
Let $M$ be any Turing machine and $x$ and $y$ two possible instantaneous descriptions of it. Show that the problem of determining whether or not $x \vdash^{*}_M y$ is und...
Rishi yadav
203
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
1
answer
228
Peter Linz Edition 5 Exercise 12.1 Question 9 (Page No. 308)
$\text{Definition:}\space$A pushdown automaton $M = (Q,\Sigma,\Gamma,\delta,q_0,z,F)$ ... that is, given a pda as in Definition, can we always predict whether or not the automaton will halt on input $w?$
$\text{Definition:}\space$A pushdown automaton $M = (Q,\Sigma,\Gamma,\delta,q_0,z,F)$ is said to be deterministic if it is an automaton as defined as defined, subject to ...
Rishi yadav
343
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
229
Peter Linz Edition 5 Exercise 12.1 Question 7,8 (Page No. 308)
$i)$ Show that there is no algorithm for deciding if any two Turing machines $M_1$ and $M_2$ accept the same language. $ii)$ How is the conclusion of $i$ affected if $M_2$ is a finite automaton$?$
$i)$ Show that there is no algorithm for deciding if any two Turing machines $M_1$ and $M_2$ accept the same language.$ii)$ How is the conclusion of $i$ affected if $M_2$...
Rishi yadav
158
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
1
answer
230
Peter Linz Edition 5 Exercise 12.1 Question 6 (Page No. 308)
Consider the question: $“$Does a Turing machine in the course of a computation revisit the starting cell $($i.e the cell under the read-write head at the beginning of the computation$)?$”$ Is this a decidable question$?$
Consider the question: $“$Does a Turing machine in the course of a computation revisit the starting cell $($i.e the cell under the read-write head at the beginning of t...
Rishi yadav
477
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
231
Peter Linz Edition 5 Exercise 12.1 Question 5 (Page No. 307)
Show that there is no problem to decide whether or not an arbitrary Turing machine on all input.
Show that there is no problem to decide whether or not an arbitrary Turing machine on all input.
Rishi yadav
164
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
232
Peter Linz Edition 5 Exercise 12.1 Question 4 (Page No. 307)
In the general halting problem, we ask for an algorithm that gives the correct answer for any $M$ and $w$. We can relax this generality, for example by looking for an algorithm that works for all $M$ but only a ... that determines whether or not $(M,w)$ halts. Show that even in this restricted setting the problem is undecidable.
In the general halting problem, we ask for an algorithm that gives the correct answer for any $M$ and $w$. We can relax this generality, for example by looking for an alg...
Rishi yadav
263
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
233
Peter Linz Edition 5 Exercise 12.1 Question 3 (Page No. 307)
Show that the following problem is undecidable. Given any Turing machine $M, a\in \Gamma $ and $w \in \Sigma^{+}$, determine whether or not the symbol $a$ is ever written when $M$ is applied to $w$.
Show that the following problem is undecidable. Given any Turing machine $M, a\in \Gamma $ and $w \in \Sigma^{+}$, determine whether or not the symbol $a$ is ever written...
Rishi yadav
134
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
theory-of-computation
decidability
proof
+
–
0
votes
0
answers
234
Peter Linz Edition 5 Exercise 12.1 Question 2 (Page No. 307)
$\text{Definition:}$ Let $w_M$ be a string that describes a Turing machine $M = (Q,\Sigma,\Gamma,\delta,q_0,\square,F)$, and let $w$ be a string in $M'$s alphabet. We will assume that $w_m$ and $w_M$ ... or not. Reexamine the proof of Theorem to show that this difference in the definition does not affect the proof in any significant way.
$\text{Definition:}$ Let $w_M$ be a string that describes a Turing machine $M = (Q,\Sigma,\Gamma,\delta,q_0,\square,F)$, and let $w$ be a string in $M’$s alphabet. We w...
Rishi yadav
169
views
Rishi yadav
asked
Mar 14, 2019
Theory of Computation
peter-linz
peter-linz-edition5
decidability
theory-of-computation
proof
+
–
2
votes
0
answers
235
Graph Degree sequence : Bondy and Murty : $1.1.16$
Let $d = (d_1,d_2,\dots, d_n)$ be a nonincreasing sequence of nonnegative integers, that is, $d_1 \geq d_2 \geq · · · \geq d_n \geq 0$. Show that: there is a loopless graph with degree sequence d if and only if $\sum_{i=1}^{n}d_i$ is even and $d_1 \leq \sum_{i=2}^{n}d_i$
Let $d = (d_1,d_2,\dots, d_n)$ be a nonincreasing sequence of nonnegative integers, that is, $d_1 \geq d_2 \geq · · · \geq d_n \geq 0$. Show that:there is a loopless g...
dd
452
views
dd
asked
Jul 4, 2017
Graph Theory
graph-theory
non-gate
proof
degree-of-graph
+
–
1
votes
0
answers
236
Graph Theory : Bondy-Murty $1.1.20$
Let $S$ be a set of $n$ points in the plane, the distance between any two of which is at least one. Show that there are at most $3n$ pairs of points of S at distance exactly one. Can this be done with a unit circle and we can place at max. $6$ points on the perimeter and doing the same for other points as well ? i.e. we can get $6n/2 = 3n$ pairs at max. ?
Let $S$ be a set of $n$ points in the plane, the distance between any two of which is at least one. Show that there are at most $3n$ pairs of points of S at distance exac...
dd
317
views
dd
asked
Jul 4, 2017
Graph Theory
graph-theory
non-gate
proof
+
–
2
votes
0
answers
237
Graphic Sequence condition
A sequence $d = (d_1,d_2,\dots , d_n)$ is graphic if there is a simple graph with degree sequence $d$ If $d = (d_1,d_2,d_3, \dots d_n)$ is graphic and $d_1 \geq d_2 \geq d_3 \geq \dots \geq d_n$ , then show that $\sum_{i=1}^{n}d_i$ is even and $\sum_{i=1}^{k}d_i \leq \left [ k(k-1) + \sum_{i=k+1}^{n} \min\{k,d_i\} \right ] \quad ,1 \leq k \leq n$.
A sequence $d = (d_1,d_2,\dots , d_n)$ is graphic if there is a simple graph with degree sequence $d$If $d = (d_1,d_2,d_3, \dots d_n)$ is graphic and $d_1 \geq d_2 \geq d...
dd
412
views
dd
asked
Jul 4, 2017
Graph Theory
non-gate
graph-theory
proof
+
–
3
votes
0
answers
238
Minimum No. of vertices required
Prove the following for graph $G$. When length of the shortest cycle in a graph is $k \geq 3$ and the minimum degree of the graph is $d$, then $G$ ... $k$.
Prove the following for graph $G$.When length of the shortest cycle in a graph is $k \geq 3$ and the minimum degree of the graph is $d$, then $G$ has minimum $\begin{alig...
dd
387
views
dd
asked
Jul 1, 2017
Graph Theory
graph-theory
proof
+
–
0
votes
1
answer
239
Divisibility Test of 11
This is the statement for Divisibility test of 11. Add and subtract digits in an alternating pattern (add digit, subtract next digit, add next digit, etc). Then check if that answer is divisible by 11. This is the proof that I found : If x is divisible by 11, then x ≡ 0 (mod ... ------------------------------------- Now, I didn't understand the proof starting from But.
This is the statement for Divisibility test of 11.Add and subtract digits in an alternating pattern (add digit, subtract next digit, add next digit, etc). Then check if t...
Uzumaki Naruto
659
views
Uzumaki Naruto
asked
May 12, 2017
Mathematical Logic
number-theory
divisibility
proof
+
–
1
votes
2
answers
240
CMI2016-B-4
Let $\Sigma = \{0, 1\}$. Let $A, \: B$ be arbitrary subsets of $\Sigma^\ast$. We define the following operations on such sets: $ A+B := \{ w \in \Sigma^\ast \mid w \in A \text{ or } w \in B \}$ ... $A$ and $B$? If yes, give a proof. If not, provide suitable $A$ and $B$ for which this equation fails.
Let $\Sigma = \{0, 1\}$. Let $A, \: B$ be arbitrary subsets of $\Sigma^\ast$. We define the following operations on such sets:$ A+B := \{ w \in \Sigma^\ast \mid w \in A...
go_editor
530
views
go_editor
asked
Dec 30, 2016
Theory of Computation
cmi2016
closure-property
proof
descriptive
+
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