On Tue, 27 Jun 2006 09:04:18 +0100, Lucas Figueiredo
<[log in to unmask]> wrote:
>On 26/06/06, Rui Carvalho <[log in to unmask]> wrote:
>> And that's where spatial networks are different: not only the
>> elements are spatially located, but the relations between these
elements are
>> also spatial (i.e. the network is weighted).
>
>Please, may you send a well known reference where is clearly stated
>that network representations of spatial systems must fit these two
>criteria to be spatial:
>
>a) being embedded in space
>b) also having spatial relations (Euclidian space prefferred)
>- the graph cannot be unweighted
>
>I am serious, if this hypothesis is true:
>"topological representations of spatial systems does not represent
>spatial systems"
>
>I may have to change the topic of my PhD.
>
Hello Lucas,
The major reference is "Network Analysis in Geography" by Haggett and
Chorley. The book was written in 1969, so I guess SS people have a bit to
catch up with...
Only the first chapter of the book ("topological structures") is dedicated
to topological networks; the second chapter opens with the following
paragraph (p57):
"Whatever the gains that accrue from viewing a network in terms of its
basic topology, it is clear that large and significant parts of its
spatial structure are missing." The second chapter is entitled "Geometric
Structures".
No one will tell you that topological networks are definitely NOT spatial.
What the literature says is that topological (unweighted) approaches to
spatial networks are quite limited and that this has been known for almost
40 years. The point is that we're no longer in the 1960s; in 2006 we have
enough computational power on a desktop PC, and we use "Spatial Networks"
to mean weighted networks.
Take home messages:
i) What Hillier and Penn wrote in the reply to Ratti is basically a dead
end for this field: SS doesn't work when the edges are weighted with
distance, so SS networks will be topological at a time when everybody else
is working with spatial (weighted) networks;
ii) Hillier and colleagues are claiming on Wikipedia that "A particularly
advanced form of spatial network derives from the theory of space syntax".
This is incorrect. In fact, SS networks are a limited and primitive form
of spatial networks. Further, see i) above.
As for your PhD, well... I would start worrying if I were you...
All the best,
Rui
>> So re-read the email I sent this morning as many times as needed and
take a
>> deep breath if you feel personal about it.
>
>??
>
>Lucas Figueiredo
>
>CASA - Centre for Advanced Spatial Analysis
>University College London
>1-19 Torrington Place
>London WC1E 7HB England
>E-mail: [log in to unmask]
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