CUT(!) and FINDALL/3 URGENT

Hi, 
    
  I have an urgent doubt. For example when I ask to prolog 
    
  ?- member( 3, [1,2,3]). 
  Yes 
    
  Is there any system variable associated with the prolog answer "Yes" or "No" ??? 
    
  I have this doubt because I want to use the answer in programs (e.g. if answer=Yes then ....) 
      
  
I know that is possible with : 
The goal member(3,[1,2,3]) succeeds and you can use that in a 
conjunction or in an if-then-else, as in 

            member(3,[1,2,3]), writeln('3 is a member of [1,2,3]) 

or 

        (member(3,[1,2,3]) -> 
                writeln(success) 
        ; 
                writeln(failure) 
        ) 

but I need to Know how I can do with CUT. 


I have to know do a problem, where objective is to implement a function where is order two lists for user. The program it will have write in screen list of the elements that belong the two simultaneously. I need do this with function findall/3. 

Example: 

The important is point 6. 
OPERAÇÕES SOBRE CONJUNTOS 
                                           MENU 


        1- Verificar se a intersecção entre 2 linhas é a lista vazia 
        2- Verificar se 2 conjuntos são disjuntos 
        3- Verificar se uma lista está ordenada 
        4- Calcular a intersecção de 2 listas 
        5- Calcular a reunião de 2 listas 
        6- To calculate the elements that simultaneously do not belong the 2 given lists        
0- Para sair do programa 


        Escolher o numero que corresponde à opcção desejada: 
|: 6. 
Introduza a 1ª lista. Deve ser escrita na forma [elem1...elemn]- [1,2,3,4].
Introduza a 2ª lista. Deve ser escrita na forma [elem1...elemn]- [1,3,4,9]. 
The result it will have: [2,9]

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Sent from the SWI Prolog forum at Nabble.com:
CUT(!) and FINDALL/3 URGENT