Combining Information from Multiple Internet Sources

Depending on the outcome of the consistency check the different entry point is used for the
weight calculation algorithm. If the consistency of the consensus was high, the agent whose result
set has the smallest distance to the consensus is selected as the agent whose weight will be equal to
1 and the algorithm in listing 3.3.3 does not require the feedback URL as an input – step 1 is
omitted. If the consistency was low, the first step of the algorithm must be performed to find the
agent.
Input: Map of results
i
a ,
r
i
provided by m Search agents – each in the
form
r 1, 2 ,...,
i = U
i U
i U
i
n where U i , U
i
2 ,...,
U
i
n
1 are URLs; feedback URL
Output: Set of weights with corresponding agents
BEGIN
1. find the agent whose result set contains URL from feedback and is
closest to consensus, set his weight to 1
2. for all other agents:
( )
find d( r
i , C)
W[
i]
=
r
( r , C)
( i) ( i)
− d
r
( i)
where
d
3. return weights
END
( )
( r
i , C)
is the Levenshtein distance
Listing 3.3.3 Weights calculation algorithm for Consensus method
Those weights are used as ranking modifiers of the results provided by the search engines,
when application is issued the same query for this algorithm. When the weights are calculated
Manager Agent sends those to the corresponding Search Agents. Depending on the distances
between results sets provided by Search Agents weight may vary from 0 to 1. Weight will be equal
to 0 when a result set has maximal distance to the anchor result set. Afterwards, when weights are
already calculated those are stored in the database in case the query is issued once more. Then
during main algorithm, which yields the consensus answer, those are used as URL ranks modifiers –
the positions of URLs are divided by those. This results in moving a certain URL to the bottom of
the list if the weight of the result set from which the URL originates is close to zero. If the weight is
equal to 0, URL position is divided by 0.01. 2
2 Like stated before, this way of ranking search engines was not tested and was disabled during tests which are described in chapter
4. Weights of all search engines were equal to 1 – URL position was not altered. However, it was implemented for future possibility
of including rankings of the search engines in the process of answers processing.
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