If � 1 L 1 ​ is decidable and � 2 L 2 ​ is recognisable then (select all that apply): The following checkbox options contain math elements, so you may need to read them in your screen reader's “reading” or “browse” mode instead of “forms” or “focus” mode. Choice 1 of 3: � 1 ∪ � 2 L 1 ​ ∪L 2 ​ is decidable. Choice 2 of 3: � 1 ∪ � 2 L 1 ​ ∪L 2 ​ is not decidable. Choice 3 of 3:Not enough information to answer.

Select all true statements, for all A, B1 pointIf A and B are decidable, then A union B is decidable.If A and B are decidable, then A intersection B is decidable.If A union B is decidable, then A is decidable and B is decidable.If A intersection B is decidable, then A is decidable and B is decidable.If A union B is decidable, then A is decidable or B is decidable.If A intersection B is decidable, then A is decidable or B is decidable.

problems of decidability and undecidability in tabular form

If L1 is regular L2 is unknown but L1-L2 is regular ,then L2 must be ans. Regular CFG Decidable Empty set

Suppose A ≤ B and B is decidable, then:1 pointA is decidableA is undecidableA could be decidable or undecidable. It depends on what A and B are.

Suppose A ≤ B and B ≤ C and C is undecidable, then:1 pointA is decidableA is undecidableB is decidableB is undecidableA could be decidable or undecidable, it depends on what A, B, C are.B could be decidable or undecidable, it depends on what A, B, C are.