whenever i write "in git, a merge commit has 2 parents", I always get "well, actually..." replies saying that a merge commit can have more than 2 parents.
but have you ever done a merge with more than 2 parents? why? (I haven't!)
(this is related to a general belief I have about teaching: in general I'm pretty willing to say "wrong" things like "merge commits have 2 parents" if the thing has been true 99% of the time in my experience and it seems like explaining the "correct" version is going to be more confusing than just letting people discover it later whenever they run into it)
Some people (e.g. me) strongly dislike it on the receiving side. In my childhood I felt extremely strongly about that approach and perceived it as being lied to. Over time my reaction mellowed out, but I still dislike it. I think my dislike is at least somewhat justified: if someone wants to be able to reason in arbitrary logically correct ways, then that deprives them of that possibility.
The way I try to satisfy both people like me and people who want the simplified version is by explicitly annotating parts as being only "morally correct" as opposed to actually true and precise.
