The model of distribution
The validity of a mathematical document A that
refers to a document B can be guaranteed only if B does not change
===> mathematical documents should be immutable
Conjectures can be prooved, theories can be
augmented ===> new versions of a document can be released
We cannot force users to maintain forever the
documents they have written ===>
need for logical names (URIs) instead of phisical names (URLs)
(e.g. "cic:/coq/INIT/Datatypes/nat.ind")
Many copies of a document can exist, possibly provided by
different servers (HTTP, FTP, ...) ===> we need "getters"
that, given an URI and an (ordered) list of servers, return the
instance of the document provided by the nearest (first) server
There is also the orthogonal naming problem ===>
need for a naming authority or a more distributed solution