Eliza uses many pattern-matching rules like this:
    If user types in "I <SOMETHING OR OTHER> YOU" then respond:
    "PERHAPS IN YOUR FANTASY WE <SOMETHING OR OTHER> EACH OTHER"

The rules are actually written in the language POP11, which will be
demonstrated later.

Eliza, unlike people, does not really grasp the grammatical structure of
English. So you could type something like
     I LIKE JOE AND JOE LIKES YOU
and get the response
     PERHAPS IN YOUR FANTASY WE LIKE JOE AND JOE LIKES EACH OTHER

To prevent this Eliza would need a better grasp of English grammar.
Making computers really UNDERSTAND English is a complex business, and is one
of the main fields of Artificial Intelligence research. It requires large and
powerful computers, since the rules of a natural language like English are
very complex.
