User:IssaRice/Computability and logic/K (set of natural numbers)

In computability theory, the set $K$ is defined as $K:=\{x:x\in W_{x}\}$, where $W_{0},W_{1},\ldots$ is a standard numbering of recursively enumerable sets.

Notation

This set is traditionally denoted $K$. I'm not sure where this comes from.