Logic - Assignment 4

CSCI 446
Artificial Intelligence
Fall 2015

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ASSIGNMENT 4

The goal of this assignment is to practice using formal logic. You will translate a series of sentences into first order logic and then use three different techniques to see if you can prove an assertion.

Part 1: Translating English into Formal Logic
For the first part, you will translate the sentences below into first order logic. These came from the famous mathemetician (and more famous writer) Lewis Carroll. You might want to check out the puzzles at the Lewis Carrol Puzzles website to see how some of them are approached.

 No kitten, that loves fish, is unteachable.
 No kitten without a tail will play with a gorilla.
 Kittens with whiskers always love fish.
 No teachable kitten has green eyes.
 No kittens have tails unless they have whiskers.

Part 2: Inference in First Order Logic
Using three approaches, try to prove the following:

My kitten who has green eyes does not love fish.

A. Forward Chaining. Use forward chaining to try to prove the previous assertion. Remember, that in order to use forward (or backward) chaining, the knowledge base must be in Horn form. So start by translating your KB into Horn clauses. Show your work in doing the translation, and then as you do the inference, show the logical progrssion so I can see how you did your reasoning.

B. Backward Chaining. Now use backward chaining to try to prove the previous assertion. You can use your KB from the previous part, but I do want to see all your steps in doing the backward chaining.

C. Resolution. Finally, use resolution to try to prove the assertion. Remember, that in order to use resolution, your KB must be in conjunctive normal form. So start by translating your KB into CNF. Show me all your work in this step. Then use resolution and show me all of your steps there, also.

Submission. Submit your work via Moodle.

Page last updated: September 30, 2015