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Figure 10: Popularity
Figure 11: Example of update frequency
be also evaluated. Articles, which are quite similar to almost of the previously
selected ones, would be also valuable. For example, when an incident happens,
the series of the report articles would be sent continuously. That is, the articles are
one of the
hottest
information at that time.
The
popularity
of the news article
a
can be also estimated by 1) the densimeter
of similar articles of
a
in a retrospective scope, and 2) the time distance of
a
and
similar articles in a retrospective scope (see Figure 10). In other words, if
a
has
many similar articles in a retrospective scope and the time distance among them is
small, the popularity of
a
is considered to be high. Thus, we have
(4.10)
where are the weight values,
k
=
m/n
is the densimeter of similar
articles, and
t
d
is the time distance between
a
and its similar articles, defined as
follows:
(4.11)
4.3
Urgency
Each real channel generally has its default update duration. However, in some
cases, the duration becomes shorter than the default one because of urgency. For
example, the channel of weather forecast would change their update frequency
when typhoon warnings were announced (see Figure 11). In this case, the default
