Using the solution you gave to Exercise 1.25, give a formal description of the machines T1andT2 depicted in Exercise 1.24

Short Answer

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The formal description is given below.

Step by step solution

01

Introduce FST

Some theoretical descriptions ofTduring machines T1 and T2 must be defined at this point. The term "finite state transducer" (FST) is used to describe a device that has a finite number of states.(Q,,r,δ,q0) tuple, where

• The finite set of states isQ.

• The input alphabet is.

• The output alphabet is r.

02

Explain the solution

Some theoretical descriptions ofTduring the use of machines T1and T2must be defined at this point. The term

• The transition functiontakes a state and an input symbol and returns a state and an output symbol.

δ:QxQxr

• The start state isq0.

The finite state transducer T1 is formally defined by the ({q1,q2},{0,1,2},{0,1},δ1,q1)., where the transition function δ1 is as follows:

Input State

0

1

2

q1

{q1,0}

{q1,0}

{q1,1}

q2

{q2,0}

{q2,0}

{q2,1}

The second FST is defined as T2=({{q1,q2,q3},{a,b},{0,1},δ1,q1). The transition function δ2 is given by:

Input State

A

B

q1

{q2,1}

{q3,1}

q2

{q3,1}

{q1,0}

q3

{q1,0}

{q2,1}

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Most popular questions from this chapter

Let 2{[00],[01][10][11]}Here, contains all columns of localid="1663175934749" 0sand1sof height two. A string of symbols in gives two rows of 0sand1s. Consider each row to be a binary number and let C={wΣ*2|thebottomrowofwisthreetimesthetoprow}. For example, [00][01][11][00]cbut [01][01][10]EC. Show that C is regular. (You may assume the result claimed in Problem 1.31.)

A finite state transducer (FST) is a type of deterministic finite automaton whose output is a string and not just accept or reject. The following are state diagrams of finite state transducers T1andT2.

Each transition of an FST is labeled with two symbols, one designating the input symbol for that transition and the other designating the output symbol. The two symbols are written with a slash, I, separating them. In T1, the transition from q1toq2has input symbol 2 and output symbol 1. Some transitions may have multiple input–output pairs, such as the transition in T1from q1to itself. When an FST computes on an input string w, it takes the input symbols w1···wnone by one and, starting at the start state, follows the transitions by matching the input labels with the sequence of symbols w1···wn=w. Every time it goes along a transition, it outputs the corresponding output symbol. For example, on input 2212011, machine T1enters the sequence of states q1,q2,q2,q2,q2,q1,q1,q1and produces output 1111000. On input abbb, T2outputs 1011. Give the sequence of states entered and the output produced in each of the following parts.

a. T1on input011

b. T1on input211

c. T1on input121

d. T1on input0202

e. T2on input b

f. T2on input bbab

g. T2on input bbbbbb

h. T2on input localid="1663158267545" ε

We define the avoids operation for languages A and B to be

AavoidsB={w|wAandwdoesntcontainanystringinBasasubstring}.

Prove that the class of regular languages is closed under the avoids operation.

Use the pumping lemma to show that the following languages arenot regulara.   A1={0η1η2η|n0}b.   A2={ωωω|ω{a,b}*}c.   A3={a2η|n0}(Here,a2ηmeansastringof2ηa's.)a.   A1={0η1η2η|n0}b.   A2={ωωω|ω{a,b}*}c.   A3={a2η|n0}(Here,a2ηmeansastringof2ηa's.)

If A is a set of natural numbers and k is a natural number greater than 1, let

Bk(A)={w|wistherepresentationinbasekofsomenumberinA}.

Here, we do not allow leading 0s in the representation of a number. For example ,B2({3,5})={11,101}and B3({3,5})={10,12}.Give an example of a set A for which B2(A)is regular butB2(A) is not regular. Prove that your example works.

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