Let me rephrase my question, then, because the diagonal lemma seems clear enough to me. What is a good definition of quining? The term isn’t used at all either in the article you linked or it the page on self-reference, which surprised me.
a computer program which takes no input and produces a copy of its own source code as its only output.
If you understand how to write a quine and you understand how the diagonal lemma works, you will find that the two concepts are basically the same thing. “Quine” is more of a computer science term than a mathematical logic term, so not all expositions of Gödel’s incompleteness theorem will mention “quining”.
Let me rephrase my question, then, because the diagonal lemma seems clear enough to me. What is a good definition of quining? The term isn’t used at all either in the article you linked or it the page on self-reference, which surprised me.
Oh! Ok, a quine is
If you understand how to write a quine and you understand how the diagonal lemma works, you will find that the two concepts are basically the same thing. “Quine” is more of a computer science term than a mathematical logic term, so not all expositions of Gödel’s incompleteness theorem will mention “quining”.