====== Lab 0 ======

~~NOTOC~~


==== Welcome to the first lab ====

  * Objectives: 
   - Become familiar with our lab procedures
   - Reacquaint ourselves with DrRacket
   - Write (recursive) function that determine the intersection and the union of two sets \\ \\

  * To begin:
   - Open a command line window. Your current working directory will be your home directory
   - Create a directory, "labs" (you can see the "man"ual pages for mkdir for more information)
   - Create a directory underneath labs, "lab0"   (see the -p option in the man pages for mkdir if you need help)
   - Download the following files into your ~/labs/lab0 directory
     - {{ :courses:cs145-201951:lab0-template.scm |The template for lab 0}}
     - {{ :courses:cs145-201951:asmt-helper.scm |helper file for lab 0}}
   - open DrRacket using the "drracket" command from the terminal window \\ \\

  * Next:
   - Open up the "lab0-template.scm" file in the Definitions window. Peruse the code and add your name where necessary.
   - Rename the file you are editing File/save as... (at least remove the template moniker!)
   - Consider the following problem statement and the associated (working!) code:
    - Define a function, called SUBSET?, that takes two inputs, AA and BB, that are lists representing sets. The function should return #t (or something that signifies TRUE) if AA is a subset of BB; #f otherwise.
   - Review the test cases. Can you add at least one appropriate TESTER expression? \\ \\

=== Problem 1 ===

Define a function, called INTERSECTION, that takes two inputs, AA and BB, that are lists representing sets.  
The function should return a list representing the INTERSECTION of the two input lists. Note:  If the input lists do not have any duplicates, then neither should the output list. However, you need not define any kind of "remove-duplicates" function. 
  * Hint: Consider the testing first how many test cases should you have? Then - what is the base case (and how would you test it?) And then, how would you break down the "other" case(s) and test(s)? Again: You should consider the test cases first. At minimum, how many are there for the non-base cases?


=== Problem 2 ===

Define a function, called UNION, just like the first problem. That is, the function takes two inputs, AA and BB, that are lists representing sets.  
The function should return a list representing the INTERSECTION of the two input lists. Note:  If the input lists do not have any duplicates, then neither should the output list. However, you need not define any kind of "remove-duplicates" function. 

 
== Are we done yet? ==

Your lab work is not complete until you have demonstrated working code to a coach (or professor) and your name is recorded as being complete! When you are done, you should save your interactions window output and submit your work.
  * Click on FILE menu => "SAVE OTHER" => "SAVE INTERACTIONS AS TEXT".
  * Don't overwrite existing files! Use lab0-interactions or something similar as the file name.

  * TO SUBMIT YOUR LAB0 DIRECTORY (assuming that I setup dropbox!) - use the command line interface. cd into your ~/labs directory, issue the command, "submit145 lab0 lab0" without the quotes. Ask for help if this command is not successful.