Hint

The predicate concatenate/3 that we defined in the lecture or the built-in predicate append/3. (They do the same thing.)

In the lecture, we saw that append can be used to concatenate two given lists.

?- append([a,b,c],[y,z],Out).
Out = [a,b,c,y,z]
    

But append can also be used in other ways. For example, to split lists into two parts.

?- append(X,Y,[a,b,c]).
X = []  
Y = [a,b,c] ;

X = [a]  
Y = [b,c] ;

X = [a,b]  
Y = [c] ;

X = [a,b,c]  
Y = [] ;

no
    

How can this be used to define prefix/2?

Solution

Back to the exercise.