I was going through the Wikipedia page on Quines and did not understand this paragraph -
A quine is a fixed point of an execution environment, when the execution environment is viewed as a function transforming programs into their outputs. Quines are possible in any Turing-complete programming language, as a direct consequence of Kleene's recursion theorem.
I did not understand -
- What is a fixed point?
- What is the Kleene's recursion theorem?
- How do these two relate with Quines?
I followed the links to both fixed point and Kleene's recursion theorem on Wikipedia but wasn't able to understand the content in there. It was a little too complex for me. I am looking for a simplified explanation of this paragraph. If it's not possible to do that (because for instance the topic requires knowledge of some higher level Computer Science concepts) that's understandable, please comment the same.