Universaly complete set means that the combination of all the logic operation in a given can achieve all of the boolean operations. It is written using curly braces `{}`. I.e `{AND, OR, NOT}` is a universaly complete set as we can perform any boolean operation using the combination of those three. In opposition, `{AND}` and `{OR}` are incomplete sets. It also exist "functional complete" gates, which are [logic gates](Logic%20gates.md) that can achieve all the boolean operation by their own, such as the [IMPLY](Logic%20gates.md#IMPLY) and [NIMPLY](Logic%20gates.md#NIMPLY) gates. Links : - [What is meant by "Functionally Complete?](https://www.youtube.com/watch?v=vY-F4pBiM8A)