These are chat archives for got-lambda/expression

25th
Aug 2016
Lars Brinkhoff
@larsbrinkhoff
Aug 25 2016 05:31
Marco Zocca
@ocramz
Aug 25 2016 07:24
If by data we mean information, then the definition should be based on a "principle of surprise": if an interpreter encodes a belief over states of nature x via a probability density p(x), informative data is taken to be whatever's "unlikely" within that worldview, i.e. - log (p (x))
(^ Shannon information)
large deviations from the mean are more informative than small ones
and so on
jensli
@jensli
Aug 25 2016 08:04
The book mentions an approach by C. A. R. Hoare that is called "abstract models" that seem to be to define data as something which have a set of operations on it and which follows certain rules. There is another approach by Thatcher, Wagner and Wright which is called "algebraic specification" which has to do with abstract algebra somehow.
Marco Zocca
@ocramz
Aug 25 2016 09:11
@jensli all algebra is abstract until you have to shove it into a computer
just kidding. I haven't read SICP and I'm sure there are many gems in there. However some definitions might be a bit ad hoc and/or stale. For example I see that the same Wagner wrote a few years later wondering why the algebraic specification approach hasn't been influential ( https://dl.acm.org/citation.cfm?id=779115 )
jensli
@jensli
Aug 25 2016 09:23
@ocramz Oh, you're investigating, nice! Please report if you're finding anything interesting. I'll think about what you might mean with your "surprise" thing.
@ocramz Is there any way someone without access to ACM:s protected articles could have a look at that paper?
Marco Zocca
@ocramz
Aug 25 2016 09:27
sci-hub.cc ?
Not Legal, but very much in the public domain.