5.6 Practical Session 5

The purpose of Practical Session 5 is to help you get familiar with Prolog's arithmetic capabilities, and to give you some further practice in list manipulation. To this end, we suggest the following programming exercises:

  1. In the text we discussed the 3-place predicate accMax which which returned the maximum of a list of integers. By changing the code slightly, turn this into a 3-place predicate accMin which returns the minimum of a list of integers.

  2. In mathematics, an n-dimensional vector is a list of numbers of length n. For example, [2,5,12] is a 3-dimensional vector, and [45,27,3,-4,6] is a 5-dimensional vector. One of the basic operations on vectors is scalar multiplication. In this operation, every element of a vector is multiplied by some number. For example, if we scalar multiply the 3-dimensional vector [2,7,4] by 3 the result is the 3-dimensional vector [6,21,12]. Write a 3-place predicate scalarMult whose first argument is an integer, whose second argument is a list of integers, and whose third argument is the result of scalar multiplying the second argument by the first. For example, the query


    should yield

    Result = [6,21,12]

  3. Another fundamental operation on vectors is the dot product. This operation combines two vectors of the same dimension and yields a number as a result. The operation is carried out as follows: the corresponding elements of the two vectors are multiplied, and the results added. For example, the dot product of [2,5,6] and [3,4,1] is 6+20+6, that is, 32. Write a 3-place predicate dot whose first argument is a list of integers, whose second argument is a list of integers of the same length as the first, and whose third argument is the dot product of the first argument with the second. For example, the query


    should yield

    Result = 32

Patrick Blackburn, Johan Bos and Kristina Striegnitz
Version 1.2.5 (20030212)