Prolog "chap11a"

Admin User, erstellt 26. Mai 2023
         /**
          * <title editable="nocomment">Chap11a</title>
          * <h1>Chap11a: assertz</h1>
          * <p>Prolog has two database manipulation commands:
          * assertz and retract. Let’s see how these are used.
          * Suppose we start with an empty database. So if we
          * give the command:</p>
          */
         ?- listing.
         /**
          * <p>then Prolog will simply respond true; the listing (of course)
          * is empty.</p><p>Suppose we now give this command:<p>
          */
         ?- assertz(happy(mia)).
         /**
          * <p>This succeeds ( assertz/1 commands always succeed). But what is
          * important is not that it succeeds, but the side-effect it
          * has on the database. For if we now give the command</p>
          */
         ?- listing.
         /**
          * <p>We get the fact. That is, the database is no longer empty:
          * it now contains the fact we asserted.</p>
          * <p>Suppose we then made four more assert commands:</p>
          */
         ?- assertz(happy(vincent)).
         ?- assertz(happy(marcellus)).
         ?- assertz(happy(butch)).
         ?- assertz(happy(vincent)).
         /**
          * <p>and then ask for a listing:</p>
          */
         ?- listing.
         /**
          * <p>All the facts we asserted are now in the knowledge base.
          * Note that happy(vincent) is in the knowledge base twice.
          * As we asserted it twice, this seems sensible.</p>
          */
Prolog "chap11a"

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