# AIMA: Knowledge Representation

> Source: https://ollybritton.com/notes/textbooks/ai-a-modern-approach/knowledge-reasoning-and-planning/knowledge-representation/ · Updated: 2021-04-04 · Tags: notes, aima

> In which we show how to represent diverse facts about the real world in a form that can be used to reason and solve problems.

## Flashcards
##### What is an ontology??
A set of concepts and categories in a subject area or domain that shows their properties and the relations between them.

##### What are general-purpose ontologies??
Ontologies that make sense in lots of special-purpose domains because they are abstract and general.

##### What is the difference between stuff and things??
You can say "a thing" but not "a stuff".

##### What are some examples of stuff??
* Butter
* Bread
* Water

##### What are some examples of things??
* Sandwiches
* A stick of butter

##### What is event calculus??
A model of time in first-order logic.

##### How can you describe physical objects in first-order logic??
As generalised events.

##### What is modal logic??
An extension of logic that adds "modes" representing concepts like belief, possibility and necessity.

##### What are semantic networks??
A graph-based representation of knowledge.

##### What are description logics??
Extensions of first-order logic that makes it easier to describe categories and properties.

##### What is a Truth Maintenance System (TMS)??
A system that allows you to withdraw facts from a knowledge base.

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