Explain me How Prolog Learn? Please¡ 1

[puntito]

I already wrote my rules and goals and everything works. But I need to understand How the Program learn new facts? How can the user add new information?

This is the fact.
state( state_name, abbreviation, capital_city, area, population, [cities] ).
What if the user wants to add information about important characters of each state.
Or if the population grow, how the user can update that fact.

 

[pimi]

How is it now?

?- hello(X).
no

?- asserta(hello(world)).
yes

?- asserta(hello(japan)).
yes

?- hello(X).
X = japan ;
X = world ;
no

?- retract(hello(world)).
yes

?- hello(X).
X = japan ;
no