[e2e] [SPAM] Re: a means to an end
touch at ISI.EDU
Thu Nov 13 07:30:55 PST 2008
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David P. Reed wrote:
> To your last question: this is relevant, because you asserted without
> qualification or caveat that ALL information (except for odd things like
> my majority example) *has a location*.
I didn't opt out of majorities having a location either.
All information is based on a physical property (actual state vs.
possible states), and physical entities have a location (which need not
be a point). That information exists only in the abstract until it is
determined (e.g., calculated, measured, etc.); that measurement itself
has a location.
> Even in trivial
> case of an RSA encrypted 32-bit word of data, stored in a 32-bit
> container, the "first bit" of data is not localized, but is smeared into
> the whole word.
I've already noted that location need not be a point. Note that an RSA
encrypted word of data isn't smeared across all packets from all parties.
>...You can talk
> about information that inherently has NO location, and doing so has
> benefits to the designer and the design space he works in. (as is the
> case with Van's work).
> In networking, it is worth thinking about this, because by abusing
> yourself of the notion of information being in a location, you can make
> better choices. Just look at "network coding" as one example - Dina
> Katabi and Crowcroft showed that in practice de-localizing information
> has many advantages. Or as a different example, consider the work of
> Trachtenberg, Minsky and Zippel on distributed set reconciliation.
> Information flows between containers in a manner that is diffused in
> space and time. Or look at a hologram or FFT - again information
> loses locality, with many benefits.
The state of a system that information represents has a location -
again, not necessarily a point. However, that information isn't useful
until it determined, which requires localization. Consider network
coding - the information is spread among a finite set of packets, each
with a specific location at a specific time -- it is NOT spread across
all packets, or abstractly "across the network". Accessing the
information means taking the distributed state and localizing the
interpretation of that state - e.g., the packets of network coding
aren't useful until they're recombined.
> But in fact, it is not the case that in modern physics information needs
> must have a location, either. You can try to approximate "localized
> information" in physics, but then you end up with laws that cannot
> describe all possible experiments. (In fact, the recent resolution of
> some of the paradoxes of black-hole information has been possible
> because Hawking admitted that information need not have a location - in
> essence, though the math is subtler than that).
Hawking's discussion focused on the loss of informatiuon, which - as I
noted - requires diving into the Liouville Theorem, and considering the
scope of the system in which conservation is determined - but we're not
talking about conservation here.
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