Midterm test 

Submit by December 5, 2007 by e-mail to zlatareva@ccsu.edu with a copy to 
gurok@aol.com

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Please remember that this is a test, and everybody must work on his own.

Feel free to submit your test in either Bulgarian or English.


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Problem 1: Explain and compare chronological backtracking and dependency-
directed backtracking based on your experiments with N-Queens code. 
Describe what you did, and how you did it in detail. Explain their role 
in ftre and jtre, respectively. 

Problem 2: The simplest kind of TMS only accepts justifications as inputs
and does not use premises, contradictions, or assumptions. Explain when
would such a TMS be useful. Give an example to illustrate your answer. 

Problem 3: Using KM*, can you prove that the unicorn is

    (a) Mythical
    (b) Magical
    (c) Horned  

from the following premises:

     If the unicorn is mythical, then it is immortal, but if it is not
     mythical, then it is a mortal mammal. If the unicorn is either
     immortal or a mammal, then it is horned. The unicorn is magical
     if it is horned.


Can this problem be solved within a forward chaining inference framework?
Explain.

Here is some help. You may use the following formalization of these 
statements (& for logical AND, V for logical OR, ~ for logical NOT):

     1.  Mythical --> Immortal
     2.  ~ Mythical --> ~ Immortal & Mammal
     3.  Immortal V Mammal --> Horned
     4.  Horned --> Magical