Slide 14.20: Variables and unification (cont.)
Slide 14.22: Rules
Home

Variables and Unification (Cont.)

Variable Example II (Cont.) 
   tape( 1, van_morrison, astral_weeks, madam_george ).
   tape( 2, beatles, sgt_pepper, a_day_in_the_life ).
   tape( 3, beatles, abbey_road, something ).
   tape( 4, rolling_stones, sticky_fingers, brown_sugar ).
   tape( 5, eagles, hotel_california, new_kid_in_town ).
One more query: 
   ?- tape( 4, rolling_stones, sticky_fingers, Song).
             /* Find just the song. */
   Song = brown_sugar        /* Which you like best */
   yes

Variable Exercise
Here are some problems for which unification sometimes succeeds and sometimes fails. Indicate the outcome of the proposed match using the yes/no buttons.

eats( fred, tomatoes ).
eats( Whom, What ).

eats( fred, Food )
eats( Person, jim ).
cd( 29, beatles, sgt_pepper).
cd( A, B, help ).
f( X, a ).
f( a, X ).
likes( jane, X ).
likes( X, jim ).
f( X, Y ).
f( P, P ).
f( foo, L ).
f( A1, A1 ).