767 research outputs found
Abstract Interpretation of Supermodular Games
Supermodular games find significant applications in a variety of models,
especially in operations research and economic applications of noncooperative
game theory, and feature pure strategy Nash equilibria characterized as fixed
points of multivalued functions on complete lattices. Pure strategy Nash
equilibria of supermodular games are here approximated by resorting to the
theory of abstract interpretation, a well established and known framework used
for designing static analyses of programming languages. This is obtained by
extending the theory of abstract interpretation in order to handle
approximations of multivalued functions and by providing some methods for
abstracting supermodular games, in order to obtain approximate Nash equilibria
which are shown to be correct within the abstract interpretation framework
Maximizing Welfare in Social Networks under a Utility Driven Influence Diffusion Model
Motivated by applications such as viral marketing, the problem of influence
maximization (IM) has been extensively studied in the literature. The goal is
to select a small number of users to adopt an item such that it results in a
large cascade of adoptions by others. Existing works have three key
limitations. (1) They do not account for economic considerations of a user in
buying/adopting items. (2) Most studies on multiple items focus on competition,
with complementary items receiving limited attention. (3) For the network
owner, maximizing social welfare is important to ensure customer loyalty, which
is not addressed in prior work in the IM literature. In this paper, we address
all three limitations and propose a novel model called UIC that combines
utility-driven item adoption with influence propagation over networks. Focusing
on the mutually complementary setting, we formulate the problem of social
welfare maximization in this novel setting. We show that while the objective
function is neither submodular nor supermodular, surprisingly a simple greedy
allocation algorithm achieves a factor of of the optimum
expected social welfare. We develop \textsf{bundleGRD}, a scalable version of
this approximation algorithm, and demonstrate, with comprehensive experiments
on real and synthetic datasets, that it significantly outperforms all
baselines.Comment: 33 page
Demonstration: Economic Analysis and Expert TestimonyâPlaintiff\u27s Conference
This article is a demonstration on the use of economic experts. The demonstration is based loosely on Mobilâs attempted take-over of Marathon Oil Company. However, the oil companies involved here are named Major, which is the second largest oil company in the United States, and Olympic, which is the largest supplier to independents. Any resemblance of Major and Olympic to any other firm, entity or person, living or not, is purely coincidental.
The demonstration is divided into two parts. The first part is the conference. A conference of plaintiffâs team will be followed by a conference of defendantâs team
Demonstration: Economic Analysis and Expert TestimonyâPlaintiff\u27s Conference
This article is a demonstration on the use of economic experts. The demonstration is based loosely on Mobilâs attempted take-over of Marathon Oil Company. However, the oil companies involved here are named Major, which is the second largest oil company in the United States, and Olympic, which is the largest supplier to independents. Any resemblance of Major and Olympic to any other firm, entity or person, living or not, is purely coincidental.
The demonstration is divided into two parts. The first part is the conference. A conference of plaintiffâs team will be followed by a conference of defendantâs team
Organizing the innovation process : complementarities in innovation networking
This paper contributes to the developing literature on complementarities in organizational design. We test for the existence of complementarities in the use of external networking between stages of the innovation process in a sample of UK and German manufacturing plants. Our evidence suggests some differences between the UK and Germany in terms of the optimal combination of innovation activities in which to implement external networking. Broadly, there is more evidence of complementarities in the case of Germany, with the exception of the product engineering stage. By contrast, the UK exhibits generally strong evidence of substitutability in external networking in different stages, except between the identification of new products and product design and development stages. These findings suggest that previous studies indicating strong complementarity between internal and external knowledge sources have provided only part of the picture of the strategic dilemmas facing firms
Substitute Valuations: Generation and Structure
Substitute valuations (in some contexts called gross substitute valuations)
are prominent in combinatorial auction theory. An algorithm is given in this
paper for generating a substitute valuation through Monte Carlo simulation. In
addition, the geometry of the set of all substitute valuations for a fixed
number of goods K is investigated. The set consists of a union of polyhedrons,
and the maximal polyhedrons are identified for K=4. It is shown that the
maximum dimension of the maximal polyhedrons increases with K nearly as fast as
two to the power K. Consequently, under broad conditions, if a combinatorial
algorithm can present an arbitrary substitute valuation given a list of input
numbers, the list must grow nearly as fast as two to the power K.Comment: Revision includes more background and explanation
Flows and Decompositions of Games: Harmonic and Potential Games
In this paper we introduce a novel flow representation for finite games in
strategic form. This representation allows us to develop a canonical direct sum
decomposition of an arbitrary game into three components, which we refer to as
the potential, harmonic and nonstrategic components. We analyze natural classes
of games that are induced by this decomposition, and in particular, focus on
games with no harmonic component and games with no potential component. We show
that the first class corresponds to the well-known potential games. We refer to
the second class of games as harmonic games, and study the structural and
equilibrium properties of this new class of games. Intuitively, the potential
component of a game captures interactions that can equivalently be represented
as a common interest game, while the harmonic part represents the conflicts
between the interests of the players. We make this intuition precise, by
studying the properties of these two classes, and show that indeed they have
quite distinct and remarkable characteristics. For instance, while finite
potential games always have pure Nash equilibria, harmonic games generically
never do. Moreover, we show that the nonstrategic component does not affect the
equilibria of a game, but plays a fundamental role in their efficiency
properties, thus decoupling the location of equilibria and their payoff-related
properties. Exploiting the properties of the decomposition framework, we obtain
explicit expressions for the projections of games onto the subspaces of
potential and harmonic games. This enables an extension of the properties of
potential and harmonic games to "nearby" games. We exemplify this point by
showing that the set of approximate equilibria of an arbitrary game can be
characterized through the equilibria of its projection onto the set of
potential games
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