# Armstrong's Axiom

Last updated: June 20, 2017

## What Does Armstrong's Axiom Mean?

Armstrong’s Axiom is a mathematical notation used to find the functional dependencies in a database. Conceived by William W. Armstrong, it is a list of axioms or inference rules that can be implemented on any relational database. It is denoted by the symbol F+.

## Techopedia Explains Armstrong's Axiom

Armstrong’s Axiom is used to analyze, refine and maintain relational databases. It has three major modes or inferences applied on a set of data. They are as follows:

• Axiom of Reflexivity: If user name (A) and title (B) represent a person's name, then the relationship between both (A and B) is of little importance.
• Axiom of Augmentation: If a user ID defines a person's name, then the user ID with email quota define the person’s name and email quota.
• Axiom of Transitivity: If a user ID determines a person's name, and a person's name defines the department, then the department can define the user ID.