>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.)
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.)