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Comment by andrewcooke | Hacker News Reader

i just did.

(1) an abstract is just a sketch of the entire paper contents.

(2) in section 2 of the paper they give a more precise meaning to indistinguishable which allows you to use any function you can think of to detect non-uniformity (roughly - there are details like it's a limit as you go to large sequences, so that any finite random pattern becomes progressively less likely, etc etc). so you can cover the case you are worried about by using a test that looks for repeated patterns of values.

[more generally, even with hn as it is these days, if you're asking for clarification rather than raising an objection, then you should probably prefix your comment with something like "i don't understand the paper, can someone please understand why...".]

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>"(1) an abstract is just a sketch of the entire paper contents."

That is not an excuse for containing a bogus definition without a warning, especially in the abstract which is the first thing that you read to tell if the paper is interesting enough to look it in depth.

It's a fine definition for an abstract. If it contained a full, precise definition, it wouldn't be an abstract. It's a single paragraph that summarizes a dense, academic 30 page paper. Everyone who reads them understands that the abstract is about the general idea, not formal correctness.

>"It's a fine definition for an abstract"

It is not. An abstract is one of the most important parts in a paper and that's why authors tend to avoid writing definitions on them but stating something like "A definition for X is given in the paper". It is meant to "describe" the paper rather than a summary or introduction of the subject in question.

In any case, writing a good abstract is hard, and it doesn't diminish the quality of this paper.

Abstracts should have an introductory sentence, and they quite often are a one paragraph summary of the work.

i agree it's kind-of a weird sentence for the start of the abstract - seems too introductory for the rest. i suspect it was added because a referee wanted the abstract to be more general, or just because they didn't know how else to start referring to PRNGs. writing papers is hard.

but it's not bogus, it's just incomplete. what i was trying to explain is that if something in an abstract doesn't make sense, you should look to the paper for a more detailed explanation.

and finally, in a "deep" way it's actually a very good definition of a PRNG. it's exactly what section 2 expands on. there's nothing you can fall back to that's more fundamental, that i can see, than it being indistinguishable from random.

Thanks.

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