Truth Tables and De Morgan's Rules

Read this chapter, which discusses Boolean variables as used in decision tables. Truth tables are used to collect variables and their values relative to decisions that have to be made within control structures.

11. Not Not



Answer:
Not always are robins not seen when the weather is not fair.
Sometimes robins are seen when the weather is not fair.
Robins are sometimes seen in poor weather.


Not Not
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It is useful to have some rules for rewriting boolean expressions. Here is an easy one:
    

    

        
            

            

            

                
                    
!!A is equivalent to A           

                		
            

        
    


    

    
The operand A stands for a true/false value or an expression that results in a true/false value. This truth table shows the rule:





    

        
            

                
A

                
!A

                
!!A

            

            

                
false

                
true

                
false

            

            

                
true

                
false

                
true

            

        
    










    

    
Question 11:
Rewrite the following if statement:
    if ( !(value != 399) )
  System.out.println("Correct Value"); 
else
  System.out.println("Wrong Value");