First order logic (FOL)
- It is a formal system used in mathematics, philosophy and computer science to represent and reason about propositions and their relationships. Unlike propositional logic, FOL allows the use of quantifiers (like “for all” and “exists”) to express more complex statements.
Fuzzy logic
- It is an approach to knowledge representation that deals with reasoning that is approximate rather than exact. It allows for presentations of concepts that are not black and white, but rather fall along a continuum with degrees of truth ranging from 0 to 1.
- It is particularly useful in domains where precise information is unavailable or impractical, such as control systems, decision making and natural language processing.
- Example: In a climate control system, fuzzy logic can be used to represent systems like “warm”, “hot” or “cold” and make decisions based on the degree to which these conditions are met, rather than relying on strict numerical thresholds.
Description logics
- They are a family of formal knowledge representation languages used to describe and reason about the concepts and relationships within a domain. They are more expressive than propositional logic, but less complex than full first order-logic making them well-suited for representing structured knowledge.
- They form the foundation of ontologies used in the semantic web and are key to building knowledge based systems that require classification, consistency checking and inferencing.
- Example: They can be used to define and categorize different types of products in an e-com system allowing for automated reasoning about product features, relationships and hierarchies.