Manipulating Information Providers Access to Information in Auctions - Technologies and Applications of Artificial Intelligence - page 22

The case where there is some uncertainty associated with the value of the sold
(auctioned) item is quite common in the literature on auctions. Most commonly
it is assumed that the value of the auctioned item is unknown to the bidders
at the time of the auction and bidders may only have an estimate or some pri-
vately known signal, such as an expert's estimate, that is correlated with the
true value [17,24]. Many of the works using uncertain common value models
assumed asymmetry in the knowledge available to the bidders and the auction-
eer regarding the auctioned item, typically having sellers more informative than
bidders [1,11]. As such, much emphasis was placed on the role of information
revelation [28,33,9,12,14,13,20,21]. In particular, several authors have consid-
ered the computational aspects of such models where the auctioneer needs to
decide on the subsets of non-distinguishable values to be disclosed to the bid-
ders [11,29,10]. Nonetheless, all these works assume the auctioneer necessarily
obtains the information and that the division into non-distinguishable groups,
whenever applicable, is always a priori given to the bidders. Furthermore, not
disclosing any information (signal) is not allowed in these works. Our problem,
on the other hand, does not require that the auctioneer possess (or purchase) the
information in the first place, and allows the auctioneer the decision of whether
or not to disclose any value even if the information is purchased. In particular,
when no information is disclosed bidders cannot distinguish between the infor-
mation not being purchased in the first place and the information is purchased
but the value is not disclosed. More importantly, none of the prior work considers
the option of influencing the ability of the information provider to distinguish
between different values.
Prior work that considers a three-ply equilibrium in settings where informa-
tion can be potentially purchased from an external information provider assumes
the information provider can always supply the true common value [34]. More-
over, this work does not allow any influence whatsoever on the auctioneer's
strategy over the ability to distinguish between different values. Work in other
domains that did consider selective information disclosure, e.g., for comparison
shopping agents [18] or for sharing data for user modeling [35] is very far in terms
of the principles used, and cannot be applied in our case. On the whole, despite
the many prior models that consider a subset of our model's characteristics, to
the best of our knowledge, an analysis that addresses all of the different aspects
included in our model does not exist in the literature.
6 Conclusions and Future Work
In this paper we advance the state of the art by providing a three player equi-
librium analysis that allows the ability of influencing the auctioneer's expected
profit through controlling the granularity and accuracy of the information of-
fered for sale. The presence of information providers in multi agent systems
has become substantial and consequently, enforces the reconsideration of the
equilibrium where this time such options are taken into account. The informa-
tion providers may be individuals with specific expertise who offer their services