Combining Information from Multiple Internet Sources

During algorithm processing there is no direct participation of the Search Agents (SAs) in the
game itself. The whole game logic is performed by the Manager Agent (MA). MA invokes all
necessary methods to perform the game. SAs in this game are used as grouping factor for result sets
– each agent corresponds to the search engine which returned a particular result set; and then result
set is assigned to an agent. Algorithm was centralized for unification purposes (Consensus method
described in 3.4 is also highly centralized algorithm) and also to achieve greater reliability and
speed that could be seriously lowered due to the communication overhead or communication
failures. In fact SAs are not necessary; those were used as a somehow interesting way to deal with
the information retrieval task.
Below the pseudo code for the main game part is presented. This part is started after the
algorithm from section 3.4.1 is finished and the result sets have been processed.
Input: Map containing URL rankings
Output: 10 URLs
BEGIN
1. repeat until there are 10 URLs in answer list
2. repeat until one agent remains
3. find agent whose URL is the highest ranked URL, find also the aforementioned URL –
let those be FA (first agent) and FAU (first agent URL)
4. find agent whose URL is the second highest ranked URL, also find the aforementioned
URL – let those be SA (second agent) and SAU (second agent URL)
5. construct keep and change payoff values as follows:
FA keep
SA keep
= rank
= rank
( FA, FAU ) − rank(
FA,
SAU )
( SA, SAU ) − rank(
SA,
FAU )
( FA FAU )
rank , + rank(
FA,
SAU )
FA change
=
2
( SA SAU )
rank , + rank(
SA,
FAU )
SA change
=
2
determine agent actions by comparison of their values – the action with higher value
is the chosen action
6. determine round winner:
−if action assigned to one of agents (FA, SA) is keep action and other is change the
one that selected keep is marked as winner, the second one is marked as loser and
is discarded from further game
−if both of them are assigned the same action their URL ranks are replaced by the
values of the chosen action; if this situation occurs second time the following
takes place:
Depending on the initial ranks of the URLs assigned to the agents the one
with the higher ranking is considered to be a winner of the round, and the
second one is loser. Then the loser and its result set is discarded from the
next rounds of the negotiation until the game is restarted (2.)
7. add URL to answer list
8. remove the URL from further evaluation
9. go to 2 (next round)
END
Listing 3.1.4 Game theory main algorithm
25