Layer Conventions

[Alexis Wieland]

Maybe I'm just a pessimist, but I think we're always going to have to
define what we mean by layers in a specific context and proceed from there.

Geoff points out that conventions become muddled when you have "skip level"
arcs (which are becoming pretty prevalent at least in our neck of the woods).
It gets worse with feedback and down right ugly with random connections
or in networks that dynamically change/grow (yes, we're playing with
those too).  And we all *know* that lateral connections within a layer
don't increase the layer count, but what about laterally connected net with
limited feedback (my graphics system starts making simplifying assumptions
about now).  It really depend on how *you* conceptualize them (or how your 
graphics draws them).  And then what about Hopfield/Boltzman/Cauchy/... nets 
which are fully bi-directionally connected? Is that one very connected layer 
or a separate layer per node; and what if it has input/output from somewhere 
else?

"Layers" are nice intuitive constructs which are enormously helpful in
describing nets, but (following the INNS preident's speaking style) it's
rather like good and evil, we all know what they are until we have to 
give precise definitions.  I have a sinking feeling that we will always
be the field that can't agree how to count.

alexis.
wieland at MITRE.arpa