Lecture 4 - Nondeterministic Turing Machines Notes | EduRev

Created by: Appar Malik

: Lecture 4 - Nondeterministic Turing Machines Notes | EduRev

 Page 1


Lecture 4
Page 2


Lecture 4
Announcements
Late policy
eT urnin
Of?ce hours M 2:30, W 12:30, Th 5:00
Midterm Fri 5/7, probably
Page 3


Lecture 4
Announcements
Late policy
eT urnin
Of?ce hours M 2:30, W 12:30, Th 5:00
Midterm Fri 5/7, probably
q
0
Rej
Rej
.
.
.
...
Accept
Rej Rej
Rej
Rej Rej
Rej
.
.
.
Accept if any 
path leads to 
q
accept
;  reject 
otherwise,
(i.e., all halting 
paths lead to 
q
reject 
)
Nondeterministic T uring Machines
d: Q × G? P(Q × G × {L,R})
Page 4


Lecture 4
Announcements
Late policy
eT urnin
Of?ce hours M 2:30, W 12:30, Th 5:00
Midterm Fri 5/7, probably
q
0
Rej
Rej
.
.
.
...
Accept
Rej Rej
Rej
Rej Rej
Rej
.
.
.
Accept if any 
path leads to 
q
accept
;  reject 
otherwise,
(i.e., all halting 
paths lead to 
q
reject 
)
Nondeterministic T uring Machines
d: Q × G? P(Q × G × {L,R})
Key issue: avoid getting lost on 8 path
Key Idea: breadth-?rst search
tree arity = |Q| x | G| x |{L,R}|  (3 in example)
Simulating an NTM
q
0
Rej
Rej
.
.
.
...
Accept
Rej Rej
Rej
Rej Rej
Rej
.
.
.
3211...
Page 5


Lecture 4
Announcements
Late policy
eT urnin
Of?ce hours M 2:30, W 12:30, Th 5:00
Midterm Fri 5/7, probably
q
0
Rej
Rej
.
.
.
...
Accept
Rej Rej
Rej
Rej Rej
Rej
.
.
.
Accept if any 
path leads to 
q
accept
;  reject 
otherwise,
(i.e., all halting 
paths lead to 
q
reject 
)
Nondeterministic T uring Machines
d: Q × G? P(Q × G × {L,R})
Key issue: avoid getting lost on 8 path
Key Idea: breadth-?rst search
tree arity = |Q| x | G| x |{L,R}|  (3 in example)
Simulating an NTM
q
0
Rej
Rej
.
.
.
...
Accept
Rej Rej
Rej
Rej Rej
Rej
.
.
.
3211...
A TM “Enumerator”
Read More
Offer running on EduRev: Apply code STAYHOME200 to get INR 200 off on our premium plan EduRev Infinity!