Research Statement
Understanding the nature of distributed decisionmaking systems is a universal challenge for scientists and engineers today. My research goal is to unveil fundamental principles of distributed systems and advance largescale decisionmaking technologies for our future society. My research projects are categorized in terms of traditional disciplinary boundaries as (1) controltheoretic, (2) informationtheoretic and (3) gametheoretic.
Control theoretic approach

Since the 1960s, control theorists have been studying how the difficulty of distributed decisionmaking problems depends on various factors, such as information structure (i.e., who knows what, when) and performance specifications (i.e., what needs to be achieved). While arbitrary combinations of these factors typically result in NPhard problems, in certain exceptional and nontrivial cases distributed control problems admit computationally tractable solutions. Discovering such classes of distributed control problems is extremely valuable, since this type of knowledge directly contributes to our ability to develop scalable infrastructures.
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Informationtheoretic approach

When multiple individuals must perform a certain task in a distributed environment, the issue of communication costs comes into the picture. Understanding the interplay between Shannon's information theory and realtime decisionmaking theory is a key mission in this context. Although the challenge here is multispectrum and numerous research activities are going on, in our view the essence of the problem can be captured by the following “datafrugal” optimal control problem:
What is the minimal information that a decisionmaker must acquire from the environment in order to complete tasks with some required accuracy?
Thorough understanding of this question leads to, for instance, the development of efficient realtime datacompression and encoding algorithms for networked control systems. It is also closely related to the issue of privacy and cybersecurity in realtime environments. The main tool we use to analyze the information flow in realtime decision systems is the “directed information theory,” which has attracted much attention in neuro/cognitive science and statistical physics in recent years.
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Gametheoretic approach

In distributed systems, an additional difficulty arises when selfinterested individuals with misaligned preferences are involved in the decisionmaking process. Game theory provides rich and elegant guidelines for understanding and resolving such situations.
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