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Comment by saithound | Hacker News Reader

Mathematicians use "just" with a specific meaning: it is not used to gloss over something that the author doesn't know how to explain. It has a purpose, useful for mathematically trained readers.

For suc a reader, "a homomorphism is just a structure preserving map" makes it clear that "homomorphism" and "structure-preserving map" can be used interchangably, and that by understanding one of the concepts, you'll immediately understand the other as well.

When you got rid of the word "just", you got rid of this connotation and changed the meaning of the sentences.

E.g. the sentence "a functional is a linear transformation" is correct; but not all linear maps are functionals, so writing "a functional is just a linear transformation" would be plain wrong in a mathematical setting.

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That would be an extremely good thing to explain in the introduction. I feel like this kind of very culturally-specific usage of everyday words is what makes math/CS papers so impenetrable for many people.

The word "easy" is another example: saying "it is easy to show X" (just?) means that X can be derived from the already stated theorems in a more-or-less mechanical way without having to introduce new concepts. It does not in any way suggest that deriving this will be "easy" for a student reading the paper.

(Of course the most challenging "easy" parts are best left as an exercise for the reader anyway...)

>Mathematicians use "just" with a specific meaning: it is not used to gloss over something that the author doesn't know how to explain. It has a purpose, useful for mathematically trained readers.

Based on the author's public profile, I'm not convinced the author is a mathematician writing "... is just ..." as rigorous formalizations for a math-trained audience.

Instead, the "is just" phrases are innocently slipping into explanations as a subconscious verbal tic caused by the The Curse of Knowledge. My previous comment on that phenomenon: https://news.ycombinator.com/item?id=28256522

(Also, as a sidebar followup to your comment, Wikipedia's page about homomorphism (https://en.wikipedia.org/wiki/Homomorphism) has this as the first sentence: "In algebra, a homomorphism is a structure-preserving map ..."

I'm guessing that a hypothetical edit to "a homomorphism is _just_ a structure-preserving map" -- in an attempt to add more refinement and precision to the definition... would be rejected and reverted back by other mathematicians.)

Sure, but the title does say plain English so this would be the sort of thing the author is trying to avoid. If that’s the meaning just write all a are b.

While I agree that the English used in the repo could be plainer, that's not remotely the same thing as "using 'just' to gloss over something that the author doesn't know how to explain", which was the complaint that goto11 made.

This has not been true in my experience, as someone who is used to talking to a mathematician during my academic life (a bit). They prefer to not use words like "just X".

They generally reply in definite statements, "this is undecidable", "this is an example of X", "this can't be done without Y", they rarely say. "X is just Y", they would probably say, "X is Y".

The "just" implies some form of detail that might be missing in the relation generally. Even my mathematical text books of pretty advanced topics rarely used "just".

Again, what you say is most likely true when math people talk amongst themselves but I don't think they do so with other non math people. I was in compsci.

"just" is used across technical academia (including philosophy) to mean "nothing over and above"

I don't understand who the audience for this glossary is.

Math students coming from another discipline?

Only some people will understand the technical meaning of "just" as intended

Both you and goto11 make a good point.

What is needed is "Mathematical English in plain English."

I think for the layperson "equivalent to" would work better than "just".

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