13.3 Recursive predicates (Ad)

Introduction

We have seen what a recursive definition is. Predicates, however, can also be recursive. On this page, we take a brief look at what a recursive predicate is. On the next page, we give an example of a recursive predicate.

What is a recursive predicate?

A recursive predicate is a predicate which satisfies these two conditions:

  1. It must have at least one rule whose body does not call the same predicate. Alternatively, this can be a fact. This is the base case.
  2. It must have at least one rule whose body does call the same predicate. This is the recursive part.

Next

On the next page, we will see a recursive predicate in action.


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