%in_stock(stock#, yes/no)
in_stock( id1942 , no ).
in_stock( id2491, yes).
in_stock( id9791, no).
in_stock( id5312, yes).
in_stock( id6132, no).
%book( stock# , title, edition, year). – stock # is a unique identfier
book( id1942, 'The C Programming Language', 1, 1978 ).
book( id2491, 'The C Programming Language', 2, 1988 ).
book( id9791, 'Pride and Prejudice' ,1 , 1813 ).
book( id9791, 'Pride and Prejudice' ,1 , 1814 ).
book( id5312, 'The Wonderful Wizard of Oz', 1, 1900).
book( id6132, 'The Touchstone', 1, 1900).
% Query for “what books are in stock and published in the year 1900?” Give the title.
q1(Title):- book(title, '1900'), in_stock('yes').