Re: controversial paper

From: Don Chiasson (don_chiasson_at_notmail.com)
Date: 09/30/03 

Date: Tue, 30 Sep 2003 00:49:16 GMT

"Mxsmanic" <mxsmanic@hotmail.com> wrote in message
news:rr8hnv8cv25ma34sjr0151tas18is6dvo9@4ax.com...
> Mok-Kong Shen writes:
>
> > See my post just sent. Please give a concrete detailed
> > example. I don't understand what you mean by 'open-ended'.
> > Note that the addresses should be able to be efficiently
> > used in actual practice.
>
> A typical office worker in the U.S. might have an internal telephone
> extension of 1212. His local telephone number might be 5551212. His
> number with the area code might be 8585551212. His international
> telephone number might be 18585551212. His Earth telephone
> number might be 118585551212. The number of his modem might
> be 12122 for other people in the office, 55512122 for people in the
> same neighborhood, 85855512122 for people in the same country,
> 185855512122 for people on the same planet, and 1185855512122
> for people in the same local planetary system.
>
> Get the idea?

There is a problem with this (admittedly simplified) model: it is not an
instantaneous code[1]. This means you can't immediately tell when a
symbol (here a telephone number) ends. Suppose you dial the local number
1212. The phone system does not know if this is the complete number or
if another digit will follow. Systems as they normally operate only make
the actual connection after receiving the complete number. Variable
length numbers are not normally used. There are fixed length groups,
e.g. in an office internal is xxxx; local is 9-xxx-xxxx; long distance
is 1-xxx-xxx-xxxx, and so on. Here the first digit gives length
information.

Having said that, there are some exceptions. 0 is operator;
0-xxx-xxx-xxxx is long distance with operator intervention. It can
get complicated for international calls where the telephone
number length depends on the country / city code. It might
be possible to have a terminator code, but that would require
major changes to the telephone system.

++Don

[1] Yes, that's the technical term.

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