[Colloquium] Talk by Nicole Immorlica, Northwestern University on November 24, 2008

[Katie Casey]

DEPARTMENT OF COMPUTER SCIENCE

UNIVERSITY OF CHICAGO

Date: Monday, November 24, 2008
Time: 3:45 p.m.
Place: RY 251

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Speaker:	Nicole Immorlica

From:		Northwestern University

Web page:	 http://www.ece.northwestern.edu/~nickle/

Title:  The Role of Compatibility in Technology Diffusion on Social  
Networks

Abstract:  In many settings, competing technologies -- for example,  
operating systems, instant messenger systems, or document formats --  
can be seen adopting a limited amount of compatibility with one  
another; in other words, the difficulty in using multiple technologies  
is balanced somewhere between the two extremes of impossibility and  
effortless interoperability. There are a range of reasons why this  
phenomenon occurs, many of which -- based on legal, social, or  
business considerations -- seem to defy concise mathematical models.  
Despite this, we show that the advantages of limited compatibility can  
arise in a very simple model of diffusion in social networks, thus  
offering a basic explanation for this phenomenon in purely strategic  
terms. Our approach builds on work on the diffusion of innovations in  
the economics literature, which seeks to model how a new technology A  
might spread through a social network of individuals who are currently  
users of technology B. We consider several ways of capturing the  
compatibility of A and B, focusing primarily on a model in which users  
can choose to adopt A, adopt B, or -- at an extra cost -- adopt both A  
and B. We characterize how the ability of A to spread depends on both  
its quality relative to B, and also this additional cost of adopting  
both, and find some surprising non-monotonicity properties in the  
dependence on these parameters: in some cases, for one technology to  
survive the introduction of another, the cost of adopting both  
technologies must be balanced within a narrow, intermediate range. We  
also extend the framework to the case of multiple technologies, where  
we find that a simple model captures the phenomenon of two firms  
adopting a limited "strategic alliance" to defend against a new, third  
technology. Joint work with J. Kleinberg, M. Mahdian, and T. Wexler.

Refreshments will be served prior to the talk in RY 255 at 3:00.