Why does he use the form: "A relation more or less correspond to" and "A relation have"? This doesn't seem to me to be unintended.
But diverges on that pattern for "domain": "a domain...corresponds".
Level 1 data science: "We have several data."
Level 100 data science: "A relation have a fixed number of attributes (columns) and each column have a domain [...]."
> This post explains what 1NF actually means and is useful for, and debunk a number of the misunderstandings.
I have never seen terms like domain and attribute used as if they were plurals (the way "data" is), but even were that correct, "a domain have" would be contradictory, so I think it is just a linguistic quirk of the writer.