big real-world networks like the Web,
as there is no full record of their evolution. Wikipedia now allows us to witness, and validate, preferential attachment at work on its graph.
The usefulness of an online encyclopedia depends on multiple factors,
including breadth and depth of coverage, organization and retrieval interface, and trustworthiness of content.
In Wikipedia more depth eventually
translates into breadth, because the
Wikipedia style guidelines recommend
the splitting of overly long articles. The
evolution of articles and links in Wikipedia allows us to model the system’s
growth. Our finding that the ratio of incomplete vs. complete articles remains
constant yields a picture of sustainable
coverage and growth. An increasing
ratio would result in thinner coverage
and diminishing utility and a decreasing ratio of incomplete vs. complete
articles to eventual stagnation of Wikipedia growth.
The idea of growth triggered by
undefined references is supported by
our second finding—that most new articles are created shortly after a corresponding reference to them is entered
into the system. We also found that
new articles are typically written by different authors from the ones behind
the references to them. Therefore, the
scalability of the endeavor is limited
not by the capacity of individual contributors but by the total size of the
model, apart from providing an in-vivo validation of Barabási’s scale-free
network-development theory, suggests that the processes we have discovered may continue to shape Wikipedia in the future. Wikipedia growth
could be limited by invisible subjective boundaries related to the interests of its contributors. Our growth
model suggests how these boundaries
might be bridged. Consider that references to nonexistent entries prompt
creation of these entries and assume
that all human knowledge forms a
fully connected network. Wikipedia’s coverage will broaden through a
breadth-first graph traversal or flood-filling process, albeit over an uneven
it turns out
that the reality
link inflation and
How far might the Wikipedia process carry us? In Jorge Luis Borges’s
1946 short story “On Exactitude in Science,” the wise men of the empire undertake to create a complete map of the
empire; upon finishing, they realize the
map was so big it coincided with the
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This work is partially funded by the European
Commission’s Sixth Framework Programme
under contract IST-2005-033331 “Software
Quality Observatory for Open Source Software
Diomidis Spinellis ( firstname.lastname@example.org) is an associate
professor of information system technologies in the
Department of Management Science and Technology
at the Athens University of Economics and Business,
Panagiotis Louridas ( email@example.com) is a software
engineer in the Greek Research and Technology Network
and a researcher at the Department of Management
Science and Technology, Athens University of Economics
and Business, Athens, Greece.