CS 540, Spring 2009: Assignment 1
Search and TSP

Locations due by Wednesday 2/4 at 7PM
Distances due by Friday 2/6 at 3PM
Code and Questions Due Thursday 2/19/08 at beginning of class

For this assignment, you are required to implement a search algorithm to solve asymmetric TSPs. You have some latitude in your selection of language and algorithm. For language, if you wish to choose a language other than C, C++, Java or Lisp, you must obtain instructor's permission. For algorithm, you should use one of the algorithms (with tuning) described in class or in the text; if you wish one other than that you need to obtain instructor's permission.

ATSPs

The basics of the problem have been described already in class. You will be using problems derived from the distance matrix for Fort Collins locations which will be put in the class account in a location TBD.

The format for problems will be similar to that found in the TSPLIB, but not exactly the same. An example looks like: 

NAME:  br17
DIMENSION:  17
EDGE_WEIGHT_SECTION
 9999    3    5   48   48    8    8    5    5    3    3    0    3    5    8    8    5
    3 9999    3   48   48    8    8    5    5    0    0    3    0    3    8    8    5
    5    3 9999   72   72   48   48   24   24    3    3    5    3    0   48   48   24
   48   48   74 9999    0    6    6   12   12   48   48   48   48   74    6    6   12
   48   48   74    0 9999    6    6   12   12   48   48   48   48   74    6    6   12
    8    8   50    6    6 9999    0    8    8    8    8    8    8   50    0    0    8
    8    8   50    6    6    0 9999    8    8    8    8    8    8   50    0    0    8
    5    5   26   12   12    8    8 9999    0    5    5    5    5   26    8    8    0
    5    5   26   12   12    8    8    0 9999    5    5    5    5   26    8    8    0
    3    0    3   48   48    8    8    5    5 9999    0    3    0    3    8    8    5
    3    0    3   48   48    8    8    5    5    0 9999    3    0    3    8    8    5
    0    3    5   48   48    8    8    5    5    3    3 9999    3    5    8    8    5
    3    0    3   48   48    8    8    5    5    0    0    3 9999    3    8    8    5
    5    3    0   72   72   48   48   24   24    3    3    5    3 9999   48   48   24
    8    8   50    6    6    0    0    8    8    8    8    8    8   50 9999    0    8
    8    8   50    6    6    0    0    8    8    8    8    8    8   50    0 9999    8
    5    5   26   12   12    8    8    0    0    5    5    5    5   26    8    8 9999
EOF
The first name gives the name of the problem. The second is the number of "cities" (or in the case of Fort Collins, locations). The next line "EDGE_WEIGHT_SECTION" flags the start of the matrix of costs. By convention, locations are numbered from 1 to DIMENSION. So the second column in the first row indicates the distance between location 1 and 2.

A solution should be represented as shown below. The first line indicates the total cost for the tour (sum of distances including from the last location back to the first). Subsequent lines show the ordering for the locations. To make it simple, each location will be on its own line and the lines together (after the cost) should form a permutation. So the first location should not appear at the end. For example, a solution to the problem above would look like: 

167
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
To make sure that everyone has implemented it properly, I will be verifying your solutions as formatted above to check your cost and that it is a legal tour (all locations once and only once). So it is very important that you follow the format EXACTLY.

For testing your program, you should run the problem above and another that I will give you when we have finished the FC distance matrix.

You should name your program atsp. Your program should take as its first 2 arguments: input file and output file. File formats MUST conform to above. You may add arguments after those if you have parameters you wish to vary.

Make sure that your README file describes what parameter settings should be used as well as what compiler and settings you use. Include a MAKEFILE if needed to run your program. In other words, make this as easy as possible for the instructor to run the code.

Search Algorithm

You should implement your choice of search algorithm from what we covered in class. You must also select parameters for implementation, e.g., ordering heuristics, neighborhood, initialization. In comments in your code, you should name the algorithm and cite your source for it.

The last 10 points will be awarded based on how well your program did on four test cases, selected from the our FC locations and from the benchmark problems available at TSPLIB (formatted to match my requirements). Each evaluation trial will be allotted up to 10 minutes of CPU time. These points will be awarded as a direct function of rank based on minimizing the tour costs. Ranks for each will be combined for a final ranking. Your program will be run on one of the machines in the first floor LINUX lab; make sure your code runs on those machines.

Part of your grade will depend on how well you followed directions and how high quality was your implementation: how well it implements the method chosen, how efficiently it has been written, how easy it is to read and how creative/well justified were your design decisions.

More Data

Unfortunately, 25 locations is not particularly large. So everyone will be asked to contribute more locations and distances. As before, excel formatted spreadsheet will be used. Each student will be asked to submit 3 locations and then assigned 3 new locations and 3 old locations to fill out in the excel spreadhseet (the old ones will be partially filled in). See top for due dates for this part.

Questions

Answers to the questions are worth 24 points.
  1. Why did you select the search algorithm that you did? How did you choose parameter settings for it? Cite any relevant literature or pilot experiments that you did.
  2. To what extent is your solution designed for ATSP? What knowledge of the domain did you use in making your design decisions? What knowledge is the program using in constructing its solutions?
  3. Other than varying number of locations, give an example of an easy and a hard problem. What seems to make the difference?
Each answer is expected be 1/2-1 page in length.

What to hand in

You can submit everything electronically if you wish, but I would prefer to receive your question answers in hardcopy.
  1. Output from two runs, one for each of two problems, in ASCII.
  2. Written answers to your questions in ASCII, PDF or PS.
  3. A file (tarfile or zip) containing the source code. You should submit this via email to howe@cs.colostate.edu by the due date/time for the assignment.
  4. A README file describing exactly how to compile and run your code and how to set the parameters, if you have any. The README should include a line that can be cut-and-pasted into the instructor's script for running as batch.
  5. And if appropriate, a makefile for compiling your code and/or a script file for running it.
Note: Your code MUST accept input in exactly the format specified. Your code MUST produce an output file whose name can be specified (no hardcoding!) as an argument and be in exactly the format specified in this document. An automated test script will be used to run your code and validate your answers. If your format does not match, you will lose all points for program correctness and quality of results!

If you are concerned about your output format, you may send an output file to the instructor UP TO 24 hours before the assignment is due to be checked for format correctness.

Clarifications