Program Assignment 3

## 80 Points Due: 4/2/01 at the start of class

 Problem

This is your first assignment in Prolog, and is intended to demonstrate a capability in the language that is difficult to implement in any other language.

Design, implement and fully test, a Prolog program that will solve the following logic problem:

Five people visit a bar for a drink of Scotch Whisky. They all have their drink served differently and by different bar staff. From the clues given below, determine which bar person served whom, how they had their Scotch and in what order they were served at the bar.

The complete set of data for this puzzle is:

 Drinkers: Weiss Muller Petit Johnson La Rue Servers Paul Carmen Hans Marcella Andy Drinks (Scotch &) Cola Ginger Ale Ice Soda Cocktail Order Served 1 2 3 4 5

The clues you have available are:

• Someone is served a Scotch & Cola by Carmen.

• Mrs. Johnson was not served her Scotch & Ginger Ale by Marcella.

• Mr. Weiss was served by Paul.

• The person who drinks Scotch & Cola wasn't served second.

• The cocktail drinker was served  last.

• Marcella served the fourth person in line but they didn't order a Scotch & Soda.

• Neither Carmen nor Hans served Mr. Petit who was third in line at the bar.

• First in line was not Miss La Rue.

For this program, there is no interactive input data. Further, your program must produce a solution within 1 minute of execution time.

 Implementation Language

For this assignment, your program must be written in Prolog. You will be programming in a "logic programming" style, as described in Chapter 15 of the text book. Since this program must be written in Prolog, appropriate use of logic programming language features is expected. In particular, you may not use any versions of `assert`, `retract`, `record`, `erase`, `flag`, or any of the other database features of Prolog.

As with prior programs, your solution must adhere to good programming style, including correct use of parameter passing, identifier naming, predicate length, commenting, headers for each predicate, etc.

 Input/Output Format

Write your program as a prolog predicate called `scotch_solution` taking 15 unbound variables as parameters, like this:

```    scotch_solution(
Drinker1, Drink1, Server1,  /* The first  in line */
Drinker2, Drink2, Server2,  /* The second in line */
Drinker3, Drink3, Server3,  /* The third  in line */
Drinker4, Drink4, Server4,  /* The fourth in line */
Drinker5, Drink5, Server5   /* The fifth  in line */
) :-  /* your implementation here */
...
```
The Curator will invoke your solution with 15 unbound variables and then print out the results using `write` goals.