NIELIT 2017 DEC Scientist B - Section B: 32

Question

The collection of Turing recognizable languages are closed under:

1. Union
2. Intersection
3. Complement
4. Concatenation
5. Star Closure

• A. (i) Only
• B. Both (i),(iv)
• C. (i),(ii),(iv)and(v)
• D. All of the options

Comments

REL are not closed under complementation among the options.

Answer 1

Option C 

RE IS NOT CLOSED UNDER COMPLEMENT.

https://gatecse.in/closure-property-of-language-families/

Answer 2

The collection of turing recognizable languages are closed under
1)Union
2)Intersection
3)Concatenation
4)Star closure

Answer 3

Option C is correct as Recursively enumerable languages are closed under every other operation except Set difference and Complementation.

Reference:  Recursively enumerable languages

Comments

"every other"?