Assignment Five: Logic Programming in Prolog

Assigned: Monday, April 12, 1998
Due: start of class, Monday, April 19, 1998

This is your final written assignment for CS302. You should spend the remaining ``assignment time'' on your presentations.

In all of the problems below, your testing should show not just that the predicates hold when given appropriate parameters, but also whether they can be used to generate appropriate values. If they cannot be used to generate values (e.g., most reverse predicates can only reverse one of their two parameters), make sure to note these limitations.

1. Reversing Lists

Define and test a binary predicate, reverse(L1,L2), that holds if list L1 is the reverse of L2. That is, it holds between two lists if and only if they contain the same elements, but in the opposite order.

2. Insertion

Define and test a trinary predicate, insert(Old,Elt,New), that holds if and only if New is the same as Old except that one copy of Elt has been added at some position (not necessarily the front). For example,

insert([a,a], b, [b,a,a])

and

insert([a,a], b, [a,b,a])

and

insert([a,a], b,[a,a,b])

all hold. However

insert([a],b,[b,a,b])

and

insert([a],b,[a,a])

should both fail.

3. Removal

Define and test a trinary predicate, remove(Old,Elt,New), that holds if and only if New is the same as Old except that one copy of Elt has been removed.

4. Permutations

Define and test a binary predicate, permutation(L1,L2), that holds when list L2 is a permutation of L1 (or vice versa). That is, permutation(L1,L2) holds if and only if L1 and L2 contain exactly the same elements, but possibly in another order.

5. Sorting Lists

Define and test a binary predicate, sorted(L1,L2), that holds between two lists if, and only if, the second contains the same elements as the first, but in sorted order. You may use any strategy you deem appropriate.

History

• Created Monday, April 12, 1999. Based on assignment 6 of CS152 98S. (Removed some problems; clarified others.)