A good book to read to get aquainted with these notions is "Meta Math" by Gregory Chaitin. The impatient can jump to chapter 5. https://arxiv.org/abs/math/040

A good book to read to get aquainted with these notions is "Meta Math" by Gregory Chaitin. The impatient can jump to chapter 5. https://arxiv.org/abs/math/0404335 https://arxiv.org/abs/math/0404335