Which of the following regular expressions denotes a language comprising all possible strings over the alphabet {a, b } ?
| A. | a* b* |
| B. | (a | b)* |
| C. | (ab)+ |
| D. | (a | b*) |
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Option: B Explanation : Click on Discuss to view users comments. |
An FSM (Finite State Machine) can be considered to be a TM (Turing Machine) of finite tape length
| A. | without rewinding capability and unidirectional tape movement. |
| B. | rewinding capacity, and unidirectional tape movement |
| C. | without rewinding capability and bidirectional tape movement |
| D. | rewinding capability and bidirectional tape movement |
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Option: A Explanation : Click on Discuss to view users comments. |
Palindromes can't be recognized by any FSM because
| A. | FSM can't remember arbitrarily large of information |
| B. | FSM can't deterministically fix the mid-point |
| C. | even if mid-point is known, FSM be can't be found whether, second half of the string matches the first half |
| D. | all of these |
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Option: D Explanation : Click on Discuss to view users comments. |
If ∑ = {a, b, c, d, e, f } then number of strings in ∑ of length 4 such that no symbol is used more than once in a string is
| A. | 35 |
| B. | 360 |
| C. | 49 |
| D. | 720 |
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Option: B Explanation : Here string length is 4 so we can create string of length 4 by 6 values. Suppose at first place we can arrange any value by 6 methods.so 6. then Remaining total numbers are 5 so we can arrange them by 5 methods at second place. then remaining total numbers are 4 so we can arrange them by 4 methods. now remaining total numbers are 3 and we can arrange them by 3 methods. so according to permutation technique. We multiply them i.e. 6*5*4*3=360. So, 'B' Click on Discuss to view users comments. richa said: (4:19pm on Saturday 13th April 2013)
this answer comes out... 6!c(6-4!)*4!
vikki gound said: (2:09am on Thursday 23rd May 2013)
thus answer of given question is total no of string=6!=720and length of each string=6-4=2 then we calculate length of string=(6c2)*4!=15*24=360so total length=720-360=360
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