CS 5970 Programming Assignment 2 — Genetic Programming

Due Monday, Sep 27, 2010

NOTE: The hardcopies of the parts of this assignment are due at the beginning of the class period. This means that if you are even a minute late, you lose 20%. If you are worried about potentially being late, turn in your assignments ahead of time. Do this by submitting them to me during office hours or by sliding them under my office door. Electronic copies are due by 4:00 pm on the due date. Submit them through D2L before the time they are due. Do not send assignments to me through email or leave them in my departmental mail box.

1. Motivation

The required components of evolutionary computation are replicators, replication, and a selection mechanism, and we require that the replication be high fidelity. When we go to create a particular evolutionary computation implementation, we need to decide on particulars for each of the requirements as well as others. Some of the questions we need to answer to create our implementations are:

All of these decisions need to be made in the context of the particular problem to which evolutionary computation will be applied (for example, the replicators in combination must be able to represent solutions to the problem in question). These decisions will also effect the unfolding of the evolutionary process (e.g., how quickly it converges to a solution).

2. Goals

The goals of this assignment are:

3. Assignment Overview

You will design, program, and run a simple genetic programming system in which each individual is a tree of operators and operands to carry out the following simple tasks:

  1. search for “food” (collecting which improves the individual’s fitness by one point) in the traditional “Sante Fe” ant-trail problem,
  2. search for food in a simple ant-trail problem that we will call “line-trail” in which all of the food is in a single line running from the starting corner along one wall in an otherwise empty 50x50 arena,
  3. search for food and avoid “poison” (collecting which harms the individual’s fitness by one point) in a slightly more complex ant-trail problem that we will call “two-lines” which is the same as line-trail except that there is a line of poison next to the line of food and enclosing it against the wall of the arena, and
  4. search for food and avoid poison in a slightly yet more complex ant-trail problem that we will call “three-lines” which is the same as two-lines except that there is a third line, this one of food, running along the far wall and starting in the opposite corner from the original food line.
See the figures below for graphical representations of the three introduced trails.

Line-Trail Figure Two-Lines Figure Three-Lines Figure
Line-Trail Two-Lines Three-Lines

You will also turn in written material regarding the design and implementation choices you made regarding the GP and an analysis of the results you will collected from your runs.

4. Assignment Details

Carry out the following steps. Underlined steps require a written response, those in code require you to write software, and those in italics require you to collect data. Written responses, code, and data will be turned in for grading

  1. Consider the choices one needs to make regarding the design and implementation of any evolutionary computation system.
  2. List the choices that need to be made when designing an evolutionary computation system that have already been made for you in this assignment. You should be able to list at least four.
  3. For each of these choices, list which option I chose for you in making this assignment.
  4. List the choices you need to make regarding the design of your GP. (Note, these do not include purely implementation choices such as programming language.) You should be able to list at least five.
  5. Choose an option that seems reasonable to you for each of these design choices and explain why it seems reasonable to you. If you do not have a good reason for your chosen option, say so.
  6. Implement your GP.
  7. Now that you have implemented your GP, you are likely to have recognized more choices that you needed to make along the way. List the choices you needed to make regarding the design of your GP. Including the choices you listed previously, your list should now contain at least ten choices.
  8. For each of these design choices, list the option you chose, and explain why it seems reasonable to you. If you do not have a good reason for your chosen option, say so.
  9. Answer the following questions about data collection, reporting, and conclusions so that you are ensured of collecting the appropriate data. Attempt to justify your answers to these questions. As you do so, keep in mind that what you want is a data set that allows you to understand the workings of your GP as an optimization tool and you want to report the minimum amount that allows your reader to thoroughly understand what you have learned. Note that you may lack a justification for your answers to some of these questions at this time. That is acceptable since this is your second assignment in this course. However, you should keep all of these questions in your mind as the course progresses and be able to give good, justified answers to similar questions for later assignments.
  10. Run your GP on each of the ant trails.
  11. Report your results and conclusions regarding the application of your GP to each ant trail.
  12. Compare the performance of your GP on each ant trail and report your conclusions.

5. What to Turn In

Write Up
You will turn in both a hard copy and an electronic copy of your write up. Your write-up should be a coherent document that covers all of the underlined steps from the assignment above. Note that selected data in a digested form (such as tables or graphs) should be included in your writeup; however, your raw data should not be included here.
Code
You will turn in both a hard copy and an electronic copy of your code. You will turn in the source code you have written for this GP. Your source code should be well structured and well commented. It should conform to good coding standards (e.g., no memory leaks).
Data
You will turn in just an electronic copy (no hard copy) of your data. This may be in a single file or multiple files. You will also need to include a brief writeup on how the data is organized.

6. Notes on this Assignment

You may write your program from scratch or may start from programs for which the source code is freely available (such as on the web or from friends or student organizations). If you do not start from scratch, you must give a complete and accurate accounting of where all of your code came from and indicate which parts are original or changed, and which you got from which other source. Similarly, for the written components of this assignment you may follow the format or content of other written works but you must give a complete and accurate accounting of who deserves credit for all parts of your documents. Failure to give credit where credit is due is academic fraud and will be dealt with accordingly. Please see the Provost's web pages on academic integrity.