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/* Answers to worksheet 1 */
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/* This stuff was already given */

/* A Zoological Example                                            */

zebedee_isa_mammal.
zebedee_has_hooves.
zebedee_has_stripes.

zebedee_isa_ungulate :- zebedee_isa_mammal, zebedee_has_hooves.

zebedee_isa_zebra :- zebedee_isa_ungulate, zebedee_has_stripes.

zebedee_has_camouflage :- zebedee_has_stripes.
zebedee_has_camouflage :- zebedee_has_spots.

/* Exercise 1.1                                                    */

/* Zebedee is a rhino if he has a horn and he has leathery skin.   */

zebedee_isa_rhino :- zebedee_has_horn, zebedee_has_leathery_skin.

/* Zebedee is a canivore if he is a mammal and eats meat, or if he */
/* has claws, pointed teeth, and his eyes point forward.           */

zebedee_isa_carnivore :- zebedee_isa_mammal, zebedee_eats_meat.
zebedee_isa_carnivore :- zebedee_has_claws, zebedee_has_pointed_teeth, 
                         zebedee_has_forward_eyes.

/* If Zebedee has feathers, he is a bird. Alternatively, if he     */
/* flies and lays eggs, he is a bird.                              */

zebedee_isa_bird :- zebedee_has_feathers.
zebedee_isa_bird :- zebedee_flies, zebedee_lays_eggs.

/* If Zebedee is a carnivore and has spots, he is a cheetah.       */

zebedee_isa_cheetah :- zebedee_isa_carnivore, zebedee_has_spots.

/* We can tell whether Zebedee is a tiger because we know          */
/* that a tiger is a canivore that has stripes.                    */

zebedee_isa_tiger :- zebedee_isa_carnivore, zebedee_has_stripes.

/* Similarly, we know that giraffes are ungulates with spots and a */
/* long neck.                                                      */

zebedee_isa_giraffe :- zebedee_isa_ungulate, zebedee_has_spots, 
                       zebedee_has_long_neck.

/* Exercise 1.2                                                    */

/* The answers to the queries will not be affected by any changes  */
/* to the ordering.                                                */

/* Exercise 1.3                                                    */

/* This rule launches an infinite computation. The system runs out */
/* of space to keep track of the progress of the computation and   */
/* so stops with an out of stack message.                          */