CSI 2120

Lab 7: Prolog

Exercise 1: Maximum and Minimum Elements

Write a Prolog program that finds the maximum and minimum element in a list of numbers. The program should work as follows:


?- maxmin([3,1,5,2,7,3],Max,Min).
Max = 7
Min = 1

?- maxmin([2],Max,Min).
Max = 2
Min = 2

Exercise 2: Odd and Even

Write a Prolog program that processes a list of numbers and outputs another list which consists of a list of the constants odd and even corresponding to the numbers.


?- oddEven([3,1,5,2,7,3],L).
L = [odd,odd,odd,even,odd,odd].

Exercise 3: List Reversal with Every Second Element

Create a Prolog program to reverse the order of the elements in a list but also remove every second element. The program should work as follows:


?- reverseDrop([3,1,5,2,7,3],L).
L = [ 7, 5, 3 ].

?- reverseDrop(['world','a','hello'],L).
L = [ 'hello', 'world' ].

Exercise 4: Adding up all the Numbers in a List

Complete the predicate below that is to add up all the numbers in a list but uses an alternating sign. Example:


?- addAlternate([5,6,1],S).
S = 0.

?- addAlternate([3,1,5,2,7,3],S).
S = 9.