If L1 is regular L2 is unknown but L1-L2 is regular ,then L2 must be
A. Empty set
B. CFG
C. Decidable
D. Regular
Answer:A
If L1 is regular L2 is unknown but L1-L2 is regular ,then L2 must be
A. Empty set B. CFG C. Decidable D. Regular
Explanation: Regular is closed under difference.