Prolog assignment 1

CMSC 331, Fall 2015, Mr. Matuszek

Due date: Sunday, November 15, at midnight

To save your work in SWISH, choose Save... from the File menu. Make your file NON-public (which really just makes it non-searchable), and fill in the following information:

Name:	[Choose your own, or let it generate one randomly]
Title:	Sally Smith, CMSC 331, Prolog assignment 1
Author:	ssmith99@umbc.edu

No tags are needed because you are not making the file public.

On saves after the first one, it will prompt you to describe your changes. This is not necessary, but is good practice.

Once you have saved your work, your location bar will display the URL, e.g., http://swish.swi-prolog.org/p/bgopGhEv.pl. You can use this URL to access your saved work in subsequent sessions. The URL can be accessed by anyone, so do not share it with anyone but the instructor. For this reason, you should allow the name to be generated randomly, or choose one that will not be easily guessed. (You also should not lose it! You may want to save your work in a local file as well.)

To submit your work, e-mail me at smatuszek@umbc.edu with the URLs of your two programs. You can do this at any time; I will not grade them until after the due date.

The due date is midnight on Sunday, November 15.

Program 1: Family relationships

The basic facts should be expressed as female/1, male/1, parent/2, and married/3.

Implement the following predicates:

• mother/2
• father/2
• son/2
• daughter/2
• sister/2 (remember, you cannot be your own sister)
• brother/2 (or your own brother... or your own anything)
• grandfather/2
• grandmother/2
• uncle/2
• aunt/2
• first_cousin/2
• ancestor/2
• descendant/2
• married/2 (this should be concluded from existing married/3 facts -- we will discuss this in class)

• stepmother/2
• stepfather/2
• relative/2 (includes relatives by both blood and marriage)

For each predicate, you should provide

• (at least) one query that should return true,
• (at least) one query that should return false,
• and (at least) one query that has one bound variable and one unbound.
• The queries that return false should not be trivially false, like asking about the same unrelated person every single time.

For example:

/** examples

?- brother(leonardo, donatello).   (true) 
?- brother(leonardo, leonardo).    (false)
?- brother(leonardo, X).           (X = donatello, X = michaelangelo, X = raphael)

*/

This may look like a lot of work, but most of these are trivial!

Program 2: List Aggregates

• first/2 returns the first element in the list.
• last/2 returns the last element in the list.
• min/2 returns the smallest element in the list.
• max/2 returns the largest element in the list.
• sum/2 returns the sum of all elements in the list.
• count/2 returns the number of elements in the list.
• mean/2 returns the arithmetic mean of the elements in the list.

• median/2

• Some of these can be done with built-in functions, such as length/2 for count/2, but I still want you to implement them recursively.
• Do not worry about handling errors such as non-numeric values.
• In all cases, the first argument is the list, and the second argument is the result. For example, mean([1, 2, 3, 8], X). should return X = 3.5.
• Remember to use is/2 to perform calculations, e.g. X is 3 + 4. => X = 7.
• first/2, last/2, min/2, max/2, mean/2, and median/2 should not return anything for empty lists.

We will discuss lists in class on Thursday. Remember the basic syntax:

• [] is the empty list.
• | is the list composition operator.
• [Head|Tail] represents the list whose first element is Head and whose remaining sublist is Tail. This is much like car and cdr.
• [Head|[]] represents the list whose first element is Head and whose remaining sublist is the empty list, i.e., the list with only one element [Head].

last([Head|[]], Head). ("the last element of a list with only one element is that element")

and a recursive case:

last([_|Tail], X) :- last(Tail, X). ("the last element of a list is the last element of the tail of that list.")