A backward$-$chaining rule$-$based system works by hypothesizing an answer and checking to see if the hypothesis is correct according to the facts given and the rules. Note that we may exhaust the hypotheses without finding any that are true.

Assume we check the hypotheses in the following order:

$?$x is a cheetah

$?$x is a tiger

$?$x is a giraffe

$?$x is a zebra

$?$x is an ostrich

$?$x is a penguin

$?$x is an albatross

And, assume we answer questions as follows:

$?$x has feathers true

$?$x flies false

$?$x swims false

$?$x has long legs true

$?$x has long neck true

$?$x is black and white true

The answers to all other questions are not known and assumed to be false.

Problem B$1$: Simulate Zookeeper$$s behavior assuming the hypotheses are tried in the order given by

the table given above and the true assertions are as given above. Indicate your answer by writing the

numbers of the rules in Table $1,$ in the order used, that are used in solving the problem. Also, name the

animal recognized selected.

$[$Follow the bellow example:$]$

Solution:

Hypothesis:

$?$x is a cheetah

Rule Z$9$:

$?$x is a carnivore

Rule Z$5$:

$?$x is a mammal

Rule Z$1$:

$?$x has hair $($true$)$

therefore

$?$x is a mammal $($true from rule Z$1)$

$?$x eats meat $($unknown and assumed false$)$

Rule Z$5$ fails

Rule Z$6$

$?$x is a mammal $($true from rule Z$1)$

$?$x has pointed teeth $($true$)$

$?$x has claws $($true$)$

$?$x has forward$-$pointing eyes $($true$)$

therefore

$?$x is a carnivore $($true from rule Z$6)$

$?$x has tawny color $($true$)$

$?$x has dark spots $($false$)$

Rule Z$9$ fails

Hypothesis:

$?$x is a tiger

Rule Z$10$:

$?$x is a carnivore $($true from rule Z$6)$

$?$x has tawny color $($true$)$

$?$x has black stripes $($true$)$

therefore

$?$x is a tiger $($true from rule Z$10)$

Therefore, the animal is a tiger