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

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.