@Ayush Upadhyaya no. If so it would have been countably infinite. A formal language also includes non recursively enumerable languages.
Formal langauges = (Class of all RE languages ) union (Class of all Non - RE languges)
as Class of formal langauges is uncoutabe and class of RE languages is countably infinite
this means (Class of Non - RE languges) is also uncountable otherwise All formal languages will be countable
M i right sir ?
Sir, I request to make more mock test of this level for GATE 2020
(Every question in this paper giving better clearity of concepts )
All statements are correct.
D is the answer.
@gmrishikumar Any set is countably infinite if you can make one-to-one correspondence of its elements with natural numbers.
In case of prime numbers, you can say that -:
1st prime = 2
2nd prime = 3
3rd prime = 5.............and so on.
Thus, they are countably infinite.