Answer:
Explanation:
If L(D1) = L(D2), the D has every state being final
If L(D1) = L¯(D2), the D has every state being final
If L(D1) = ∅, then L(D) = L(D2).
If L(D1)=Σ, L(D) = L(D2)
 
        
             
        
        
        
Because the string is invalid or your source is not attached to your search engine.
        
                    
             
        
        
        
Answer:
Symmetric encryption or single key encryption