Predefined Predicates in Prolog

1. Permutation

Explanation:

The permutation/2 predicate is used to generate permutations of a given list.

Parameters:

• permutation(List, PermutedList): List is the input list, and PermutedList is the list of all possible permutations of List.

Use Case:

Generate all possible permutations of a list.

Example:

?- permutation([a, b, c], Permutations).

2. Append

Explanation:

The append/3 predicate is used to concatenate two lists.

Parameters:

• append(List1, List2, Result): List1 and List2 are the input lists to be concatenated, and Result is the concatenated list.

Use Case:

Concatenate two lists into one.

Example:

?- append([1, 2], [3, 4], ConcatenatedList).

3. Bagof

Explanation:

The bagof/3 predicate is used to gather solutions to a query and store them in a bag (list).

Parameters:

• bagof(Variables, Condition, Bag): Variables are the variables to be collected, Condition is the query condition, and Bag is the list that contains the collected solutions.

Use Case:

Gather all solutions to a query into a list.

Example:

?- bagof(Score, student_score(Student, Score), Scores).

4. Delete

Explanation:

The delete/3 predicate is used to remove elements from a list.

Parameters:

• delete(Element, List, Result): Element is the element to be removed, List is the input list, and Result is the resulting list after removal.

Use Case:

Remove all occurrences of an element from a list.

Example:

?- delete(apple, [apple, banana, apple, orange], Result).

5. Findall

Explanation:

The findall/3 predicate is used to find all solutions to a query and collect them into a list.

Parameters:

• findall(Variables, Condition, List): Variables are the variables to be collected, Condition is the query condition, and List is the list that contains all collected solutions.

Use Case:

Find all instances satisfying a condition and collect them into a list.

Example:

?- findall(Fruit, likes(_, Fruit), LikedFruits).

6. Nth0

Explanation:

The nth0/3 predicate is used to find the element at a specific index in a list.

Parameters:

• nth0(Index, List, Element): Index is the index of the desired element, List is the input list, and Element is the element at the specified index.

Use Case:

Retrieve the element at a specific index in a list.

Example:

?- nth0(2, [apple, banana, orange], Element).

7. Member

Explanation:

The member/2 predicate is used to check if an element belongs to a list.

Parameters:

• member(Element, List): Element is the element to be checked, and List is the input list.

Use Case:

Check if an element exists in a list.

Example:

?- member(apple, [apple, banana, orange]).

8. Sumlist

Explanation:

The sumlist/2 predicate is used to compute the sum of all elements in a list.

Parameters:

• sumlist(List, Sum): List is the input list, and Sum is the sum of all elements in the list.

Use Case:

Compute the sum of all elements in a list.

Example:

?- sumlist([1, 2, 3, 4], Sum).

9. Sort

Explanation:

The sort/2 predicate is used to sort a list in ascending order.

Parameters:

• sort(List, SortedList): List is the input list, and SortedList is the sorted version of the list.

Use Case:

Sort a list in ascending order.

Example:

?- sort([3, 1, 4, 1, 5, 9, 2, 6], SortedList).

10. Length

Explanation:

The length/2 predicate is used to determine the length of a list.

Parameters:

• length(List, Length): List is the input list, and Length is the length of the list.

Use Case:

Determine the length of a list.

Example:

?- length([a, b, c, d, e], Length).

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This README provides a comprehensive overview of the predefined predicates in Prolog, along with their explanations, parameters, use cases, and implementation examples.