Teaching TN TRB CS Mock Test Theory of Computation Recursively Enumerable Sets, Turing Machines and Undecidability Undecidability
Which of the following options is INCORRECT?
1
If L is a recursive language, L' is also recursive.
2
If L and L' both are recursively enumerable, L and L' are recursive.
3
Union of two recursively enumerable languages is recursively enumerable.
4
The cartesian product of two countable sets is uncountable.