Deterministic Symmetry Breaking in Ring Networks

We study a distributed coordination mechanism for uniform agents located on a circle. The agents perform their actions in synchronised rounds. At the beginning of each round an agent chooses the direction of its movement from clockwise, anticlockwise, or idle, and moves at unit speed during this round. Agents are not allowed to overpass, i.e., when an agent collides with another it instantly starts moving with the same speed in the opposite direction (without exchanging any information with the other agent). However, at the end of each round each agent has access to limited information regarding its trajectory of movement during this round. We assume that $n$ mobile agents are initially located on a circle unit circumference at arbitrary but distinct positions unknown to other agents. The agents are equipped with unique identifiers from a fixed range. The {\em location discovery} task to be performed by each agent is to determine the initial position of every other agent. Our main result states that, if the only available information about movement in a round is limited to %information about distance between the initial and the final position, then there is a superlinear lower bound on time needed to solve the location discovery problem. Interestingly, this result corresponds to a combinatorial symmetry breaking problem, which might be of independent interest. If, on the other hand, an agent has access to the distance to its first collision with another agent in a round, we design an asymptotically efficient and close to optimal solution for the location discovery problem.Comment: Conference version accepted to ICDCS 201

Go West Young Man: Self-selection and Endogenous Property Rights

If, as Hume argues, property is a self-referring custom of a group of people, then property rights depend on how that group forms and orders itself. In this paper we investigate how people construct a convention for property in an experiment in which groups of self-selected individuals can migrate between three geographically separate regions. We find that the absence of property rights clearly decreases wealth in our environment and that interest in establishing property rights is a key determinant of the decision to migrate to a new region. Theft is nearly eliminated among migrants, resulting in strong growth, and non-migrants remain in poverty. Thus, self-selection, through the decision to migrate, to form more cooperative groups is essential for establishing property rights.experimental economics, property rights, migration and exit

ENHANCED HOST DISCOVERY IN SDN/FABRIC-BASED NETWORKS

Various solutions are provided herein to facilitate the efficient discovery of hosts in large network environments, such as software-defined networking (SDN) or fabric-based networks, utilizing several techniques. A first technique supports the ability to efficiently manage silent ports and silent media access control (MAC) addresses. This technique involves applying a novel heuristic to ports and MAC addresses, classifying such entities (as silent, quiet, and noisy), and intelligently polling such entities. A second technique supports a Multicast Listener Discovery (MLD)-based host discovery approach that is applicable to Internet Protocol (IP) version 4 (IPv4) and involves a host creating an IP version 6 (IPv6) address that embeds its IPv4 address, the addition of a well-known first byte to the three bytes in a Solicited-Node multicast address (SNMA), and the use of a form of unicast ping to confirm whether a host formed a derived address. A third technique involves using a service lookup for deterministic host discovery that involves the use of upper-layer discovery services to cause a host to expose its addresses in the replies to multicast discoveries

Cognitive modeling of social behaviors

To understand both individual cognition and collective activity, perhaps the greatest opportunity today is to integrate the cognitive modeling approach (which stresses how beliefs are formed and drive behavior) with social studies (which stress how relationships and informal practices drive behavior). The crucial insight is that norms are conceptualized in the individual mind as ways of carrying out activities. This requires for the psychologist a shift from only modeling goals and tasks —why people do what they do—to modeling behavioral patterns—what people do—as they are engaged in purposeful activities. Instead of a model that exclusively deduces actions from goals, behaviors are also, if not primarily, driven by broader patterns of chronological and located activities (akin to scripts). To illustrate these ideas, this article presents an extract from a Brahms simulation of the Flashline Mars Arctic Research Station (FMARS), in which a crew of six people are living and working for a week, physically simulating a Mars surface mission. The example focuses on the simulation of a planning meeting, showing how physiological constraints (e.g., hunger, fatigue), facilities (e.g., the habitat’s layout) and group decision making interact. Methods are described for constructing such a model of practice, from video and first-hand observation, and how this modeling approach changes how one relates goals, knowledge, and cognitive architecture. The resulting simulation model is a powerful complement to task analysis and knowledge-based simulations of reasoning, with many practical applications for work system design, operations management, and training

Position discovery for a system of bouncing robots

International audienceA collection of n anonymous mobile robots is deployed on a unit-perimeter ring or a unit-length line segment. Every robot starts moving at constant speed, and bounces each time it meets any other robot or segment endpoint, changing its walk direction. We study the problem of position discovery, in which the task of each robot is to detect the presence and the initial positions of all other robots. The robots cannot communicate or perceive information about the environment in any way other than by bouncing nor they have control over their walks which are determined by their initial positions and their starting directions. Each robot has a clock allowing it to observe the times of its bounces. We give complete characterizations of all initial configurations for both the ring and the segment in which no position detection algorithm exists and we design optimal position detection algorithms for all feasible configurations

Pintu Terlarang a Disconcerting Spatial Interpretation of Urban Dystopia

The main character of the film Pintu terlarang (The forbidden door), Gambir, attains success in the art world by making statues of pregnant women. Part of his creative process is to insert dead foetuses into the wombs of the statues. His troubled soul meets a written request for help by a child he encounters in various places. The journey to find the child leads him to a secret door, revealing a terrifying reality of a dehumanized world. The city, commonly characterized by a sense of vastness, is set in opposition to small, enclosed spaces where individuals converse with their utmost self. The questions explored are: What is the role of space in engendering urban dystopia? In what ways does the selection of different space settings help create a dehumanized world? I argue that urban dystopia is created when the inhabitants of a city return to enclosed spaces in an effort to find an existence. When individuals prefer enclosed spaces and fail to reconstruct existing meanings, tendencies toward dystopia will come forward and city life will degenerate

Foreword: Brewer v. Williams--A Hard Look at a Discomfiting Record

In recent decades, few matters have split the Supreme Court, troubled the legal profession, and agitated the public as much as the police interrogation-confession cases. The recent case of Brewer v. Williams3 is as provocative as any, because the Supreme Court there revdrsed the defendant\u27s conviction for the savage murder of a small child even though no Justice denied his guilt,4 he was warned of his rights no fewer than five times, 5 and any interrogation that might have occurred seemed quite mild.

Foreword: Brewer v. Williams--A Hard Look at a Discomfiting Record

In recent decades, few matters have split the Supreme Court, troubled the legal profession, and agitated the public as much as the police interrogation-confession cases. The recent case of Brewer v. Williams3 is as provocative as any, because the Supreme Court there revdrsed the defendant\u27s conviction for the savage murder of a small child even though no Justice denied his guilt,4 he was warned of his rights no fewer than five times, 5 and any interrogation that might have occurred seemed quite mild.