Assignment 3

Write and document a Python program that uses both forward and backward chaining to determine if a given symbol is entailed by a definite clause knowledge base. You have been given Python files myDCKBClasses.py and testDCKB.py and you need to fill in the function definitions in file mDCKBFunctions.template according to the specified algorithms given in Lecture #14 to create a file myDCKBFunctions.py such that testDCKB.py (when run using python3 on the CS departmental LabNet systems) can exactly reproduce the outputs in script file out.script with respect to the definite clause files DCClause1.txt, DCClause2.txt, and DCClause3.txt and the fact files DCFact1a.txt, DCFact1b.txt, DCFact1c.txt, DCFact1d.txt, DCFact2a.txt, DCFact2b.txt, DCFact3a.txt, and DCFact3b.txt.

You are not allowed to modify any of the code in provided files testDCKB.py and myDCKBClasses.py. When modifying file myDCKBFunctions.template to create myDCKBFunctions.py, you cannot:

• modify the lone import statement;
• add other import statements (this includes import statements added automatically by IDEs such as PyCharm);
• add, modify, or remove function definitions or modify given comments associated with those functions;
• add new class definitions or global variables (use the provided classes in file mySearchClasses.py); or
• access any provided class attributes directly (use provided attribute access functions in file mySearchClasses.py).

Violations of any of these constraints will result in severe mark deductions (see assignment evaluation scheme below).

Hints

You may find it useful to progress through the given tests in the given order when debugging your code.

You may have to modify the given algorithms to accommodate the situation in which the given symbol is not part of the given definite clause knowledge base.

Assignment Submission

Please submit your program file myDCKBFunctions.py through the course D2L / Brightspace shell by 11:59pm on the assignment due date. Note that each program file must have the following comment block at the top, where the X's are replaced with the appropriate information. For example, my Python file for this assignment would begin with the following comment block:

#########################################################
##  CS 3200 (Fall 2025), Assignment #3                 ##
##   Script File Name: myDCKBFunctions.py              ##
##       Student Name: Todd Wareham                    ##
##         Login Name: harold                          ##
##              MUN #: 8008765                         ##
#########################################################

You do not have to develop your code on our CS departmental LabNet systems. However, as your code will be tested on our CS departmental LabNet systems as part of the assignment marking process, you should ensure that your code compiles and runs correctly on at least one of these systems.

Additional Notes:

• October 26, 2025
  Assignment #3 due date changed to December 2.

• October 2, 2025
  Assignment #3 posted.

Created: October 2, 2025
Last Modified: October 2, 2025