Chris Hanson

Bio: Chris Hanson is an academic researcher from Massachusetts Institute of Technology. The author has contributed to research in topics: Information privacy & Privacy policy. The author has an hindex of 6, co-authored 6 publications receiving 919 citations.

Amorphous computing

Abstract: ion to Continuous Space and Time The amorphous model postulates computing particles distributed throughout a space. If the particles are dense, one can imagine the particles as actually filling the space, and create programming abstractions that view the space itself as the object being programmed, rather than the collection of particles. Beal and Bachrach [10, 4] pursued this approach by creating a language, Proto, where programmers specify the behavior of an amorphous computer as though it were a continuous material filling the space it occupies. Proto programs manipulate fields of values spanning the entire space. Programming primitives are designed to make it simple to compile global operations to operations at each point of the continuum. These operations are approximated by having each device represent a nearby chunk of space. Programs are specified in space and time units that are independent of the distribution of particles and of the particulars of communication and execution on those particles (Figure 5). Programs are composed functionally, and many of the details of communication and composition are made implicit by Proto’s runtime system, allowing complex programs to be expressed simply. Proto has been applied to applications in sensor networks like target tracking and threat avoidance, to swarm robotics and to modular robotics, e.g., generating a planar wave for coordinated actuation. Newton’s language Regiment [45, 44] also takes a continuous view of space and time. Regiment is organized in terms of stream operations, where each stream represents a time-varying quantity over a part of space, for example, the average value of the temperature over a disc of a given radius centered at a designated point. Regiment, also a functional language, is designed to gather streams of data from regions of the amorphous computer and accumulate them at a single point. This assumption allows Regiment to provide region-wide summary functions that are difficult to implement in Proto.

Transparent Accountable Data Mining: New Strategies for Privacy Protection

Abstract: Attempts to address issues of personal privacy in a world of computerized databases and information networks from security technology to data protection regulation to Fourth Amendment law jurisprudence -- typically proceed from the perspective of controlling or preventing access to information. We argue that this perspective has become inadequate and obsolete, overtaken by the ease of sharing and copying data and of aggregating and searching across multiple data bases, to reveal private information from public sources. To replace this obsolete framework, we propose that issues of privacy protection currently viewed in terms of data access be re-conceptualized in terms of data use. From a technology perspective, this requires supplementing legal and technical mechanisms for access control with new mechanisms for transparency and accountability of data use. In this paper, we present a technology infrastructure -- the Policy Aware Web -- that supports transparent and accountable data use on the World Wide Web, and elements of a new legal and regulatory regime that supports privacy through provable accountability to usage rules rather than merely data access restrictions.

Using Dependency Tracking to Provide Explanations for Policy Management

Abstract: Explanations for decisions made by a policy framework allow end users to understand how the results were obtained, increase trust in the policy decision and enforcement process, and enable policy administrators to ensure the correctness of the policy. In our framework, an explanation for any statement including a policy decision is a representation of the list of reasons (known as dependencies) associated with its derivation. Dependency tracking involves maintaining the list of reasons (statements and rules) for the derivation of a new statement. In this paper, we describe our policy approach that (i) provides explanations for policy decisions, (ii) provides more efficient and expressive reasoning through the use of nested sub-rules and goal direction, and (Hi) is grounded in semantic Web technologies. We discuss the characteristics of our approach and provide a brief overview of the AIR policy language that implements it. We also discuss how relevant explanation information is identified and presented to end users and describe our preliminary graphical user interface.

Data-Purpose Algebra: Modeling Data Usage Policies

Abstract: Data is often encumbered by restrictions on the ways in which it may be used. These restrictions on usage may be determined by statute, by contract, by custom, or by common decency, and they are used to control collection of data, diffusion of data, and the inferences that can be made over the data. In this paper, we present a data-purpose algebra that can be used to model these kinds of restrictions in various different domains. We demonstrate the utility of our approach by modeling part of the Privacy Act (5 USC xi552a)1, which states that data collected about US citizens can be used only for the purposes for which it was collected. We show (i) how this part of the Privacy act can be represented as a set of restrictions on data usage, (ii) how the authorized purposes of data flowing through different government agencies can be calculated, and (iii) how these purposes can be used to determine whether the Privacy Act is being enforced appropriately.

Consensus and Cooperation in Networked Multi-Agent Systems

Abstract: This paper provides a theoretical framework for analysis of consensus algorithms for multi-agent networked systems with an emphasis on the role of directed information flow, robustness to changes in network topology due to link/node failures, time-delays, and performance guarantees. An overview of basic concepts of information consensus in networks and methods of convergence and performance analysis for the algorithms are provided. Our analysis framework is based on tools from matrix theory, algebraic graph theory, and control theory. We discuss the connections between consensus problems in networked dynamic systems and diverse applications including synchronization of coupled oscillators, flocking, formation control, fast consensus in small-world networks, Markov processes and gossip-based algorithms, load balancing in networks, rendezvous in space, distributed sensor fusion in sensor networks, and belief propagation. We establish direct connections between spectral and structural properties of complex networks and the speed of information diffusion of consensus algorithms. A brief introduction is provided on networked systems with nonlocal information flow that are considerably faster than distributed systems with lattice-type nearest neighbor interactions. Simulation results are presented that demonstrate the role of small-world effects on the speed of consensus algorithms and cooperative control of multivehicle formations

Types and Programming Languages

Abstract: A type system is a syntactic method for automatically checking the absence of certain erroneous behaviors by classifying program phrases according to the kinds of values they compute. The study of type systems -- and of programming languages from a type-theoretic perspective -- has important applications in software engineering, language design, high-performance compilers, and security.This text provides a comprehensive introduction both to type systems in computer science and to the basic theory of programming languages. The approach is pragmatic and operational; each new concept is motivated by programming examples and the more theoretical sections are driven by the needs of implementations. Each chapter is accompanied by numerous exercises and solutions, as well as a running implementation, available via the Web. Dependencies between chapters are explicitly identified, allowing readers to choose a variety of paths through the material.The core topics include the untyped lambda-calculus, simple type systems, type reconstruction, universal and existential polymorphism, subtyping, bounded quantification, recursive types, kinds, and type operators. Extended case studies develop a variety of approaches to modeling the features of object-oriented languages.

The design space of wireless sensor networks

Abstract: In the recent past, wireless sensor networks have found their way into a wide variety of applications and systems with vastly varying requirements and characteristics. As a consequence, it is becoming increasingly difficult to discuss typical requirements regarding hardware issues and software support. This is particularly problematic in a multidisciplinary research area such as wireless sensor networks, where close collaboration between users, application domain experts, hardware designers, and software developers is needed to implement efficient systems. In this article we discuss the consequences of this fact with regard to the design space of wireless sensor networks by considering its various dimensions. We justify our view by demonstrating that specific existing applications occupy different points in the design space.

Developing multiagent systems: The Gaia methodology

Abstract: Systems composed of interacting autonomous agents offer a promising software engineering approach for developing applications in complex domains. However, this multiagent system paradigm introduces a number of new abstractions and design/development issues when compared with more traditional approaches to software development. Accordingly, new analysis and design methodologies, as well as new tools, are needed to effectively engineer such systems. Against this background, the contribution of this article is twofold. First, we synthesize and clarify the key abstractions of agent-based computing as they pertain to agent-oriented software engineering. In particular, we argue that a multiagent system can naturally be viewed and architected as a computational organization, and we identify the appropriate organizational abstractions that are central to the analysis and design of such systems. Second, we detail and extend the Gaia methodology for the analysis and design of multiagent systems. Gaia exploits the aforementioned organizational abstractions to provide clear guidelines for the analysis and design of complex and open software systems. Two representative case studies are introduced to exemplify Gaia's concepts and to show its use and effectiveness in different types of multiagent system.

The second wave of synthetic biology: from modules to systems

Abstract: Synthetic biology is a research field that combines the investigative nature of biology with the constructive nature of engineering. Efforts in synthetic biology have largely focused on the creation and perfection of genetic devices and small modules that are constructed from these devices. But to view cells as true 'programmable' entities, it is now essential to develop effective strategies for assembling devices and modules into intricate, customizable larger scale systems. The ability to create such systems will result in innovative approaches to a wide range of applications, such as bioremediation, sustainable energy production and biomedical therapies.