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Exercise11.md

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Exercise 11 - Logic Programming

If you do not finish during the lecture period, please finish it as homework.

Exercise 11.1 - Warmup

Install SWI Prolog from swi-prolog.org.

Create a new file named family.pl and put the following content:

male(albert).
male(bob).
male(bill).
male(carl).
male(charlie).
male(dan).
male(edward).

female(alice).
female(betsy).
female(diana).

parent(albert, bob).
parent(albert, betsy).
parent(albert, bill).

parent(alice, bob).
parent(alice, betsy).
parent(alice, bill).

parent(bob, carl).
parent(bob, charlie).
parent(diana, charlie).

Run swipl family.pl and play with the interactive prompt:

  • male(charlie).
  • female(charlie).
  • parent(X, charlie). (press ; or n for next result)
  • Write a query to find all grandparents of Charlie
  • Write a query to find only grandmothers of Charlie
  • Write a query to find all siblings of Bob
  • trace., then repeat the last query
  • Try to query X. to print ALL THINGS POSSIBLE IN THE UNIVERSE!
  • Use halt. or Ctrl+D (EOF) to exit the interactive prompt

Exercise 11.2 - Palindrome

Write a predicate palindrome_list/1 that checks if a list of atoms is a palindrome.
Hint: have look at the reverse/2 predicate.

Write a predicate palindrome/1 that checks if an atom (or string) is a palindrome.
Hint: have a look at the name/2, atom_codes/2 and string_codes/2 predicates.

Exercise 11.3 - Solve a Logical

Write a prolog program that derives a solution for the following logical:

Once upon a time a farmer went to a market and purchased a wolf, a goat, and a cabbage. On his way home, the farmer came to the bank of a river and rented a boat. But crossing the river by boat, the farmer could carry only himself and a single one of his purchases: the wolf, the goat, or the cabbage.

If left unattended together, the wolf would eat the goat, or the goat would eat the cabbage.

The farmer's challenge was to carry himself and his purchases to the far bank of the river, leaving each purchase intact. How did he do it?

Source

Hint 1: The problem is very similar to the one in cannibals.pl.
Hint 2: Only 7 river crossings are needed for solving the puzzle.