PROLOG was created in 1972 and it has been used since then, mostly in relational databases, natural languages comprehension and automation.
Continuing from the last post, I will again start with some theory before continuing to write our family code.
In logical programming, we are focused on knowledge and not in the algorithms. That is also why the code sometimes looks like a database. This programming paradigm (which one could also include PROLOG) is based on formal logic, more specific based on predicate logic.
This means that PROLOG has a set of sentences in logic form, called clauses. All clauses that we wrote in the last post are facts. They are the simplest type of clauses, also known as Horn clauses.