Collisionless Pattern Discovery in Robot Swarms Using Deep Reinforcement Learning

We present a deep reinforcement learning-based framework for automatically discovering patterns available in any given initial configuration of fat robot swarms. In particular, we model the problem of collision-less gathering and mutual visibility in fat robot swarms and discover patterns for solving them using our framework. We show that by shaping reward signals based on certain constraints like mutual visibility and safe proximity, the robots can discover collision-less trajectories leading to well-formed gathering and visibility patterns

Asynchronous Gathering of Robots with Finite Memory on a Circle under Limited Visibility

Consider a set of $n$ mobile entities, called robots, located and operating on a continuous circle, i.e., all robots are initially in distinct locations on a circle. The \textit{gathering} problem asks to design a distributed algorithm that allows the robots to assemble at a point on the circle. Robots are anonymous, identical, and homogeneous. Robots operate in a deterministic Look-Compute-Move cycle within the circular path. Robots agree on the clockwise direction. The robot's movement is rigid and they have limited visibility $\pi$, i.e., each robot can only see the points of the circle which is at an angular distance strictly less than $\pi$ from the robot. Di Luna \textit{et al}. [DISC'2020] provided a deterministic gathering algorithm of oblivious and silent robots on a circle in semi-synchronous (\textsc{SSync}) scheduler. Buchin \textit{et al}. [IPDPS(W)'2021] showed that, under full visibility, $\mathcal{OBLOT}$ robot model with \textsc{SSync} scheduler is incomparable to $\mathcal{FSTA}$ robot (robots are silent but have finite persistent memory) model with asynchronous (\textsc{ASync}) scheduler. Under limited visibility, this comparison is still unanswered. So, this work extends the work of Di Luna \textit{et al}. [DISC'2020] under \textsc{ASync} scheduler for $\mathcal{FSTA}$ robot model

Gathering on a Circle with Limited Visibility by Anonymous Oblivious Robots

A swarm of anonymous oblivious mobile robots, operating in deterministic Look-Compute-Move cycles, is confined within a circular track. All robots agree on the clockwise direction (chirality), they are activated by an adversarial semi-synchronous scheduler (SSYNCH), and an active robot always reaches the destination point it computes (rigidity). Robots have limited visibility: each robot can see only the points on the circle that have an angular distance strictly smaller than a constant ϑ from the robot’s current location, where 0 < ϑ ≤ π (angles are expressed in radians). We study the Gathering problem for such a swarm of robots: that is, all robots are initially in distinct locations on the circle, and their task is to reach the same point on the circle in a finite number of turns, regardless of the way they are activated by the scheduler. Note that, due to the anonymity of the robots, this task is impossible if the initial configuration is rotationally symmetric; hence, we have to make the assumption that the initial configuration be rotationally asymmetric. We prove that, if ϑ = π (i.e., each robot can see the entire circle except its antipodal point), there is a distributed algorithm that solves the Gathering problem for swarms of any size. By contrast, we also prove that, if ϑ ≤ π/2, no distributed algorithm solves the Gathering problem, regardless of the size of the swarm, even under the assumption that the initial configuration is rotationally asymmetric and the visibility graph of the robots is connected. The latter impossibility result relies on a probabilistic technique based on random perturbations, which is novel in the context of anonymous mobile robots. Such a technique is of independent interest, and immediately applies to other Pattern-Formation problems

Who shares wins? Understanding barriers to information sharing in managing supply chain risk.

Currently there is no universally accepted approach to supply chain risk management and assurance. To begin to shed more light on the practical operational challenges presented when considering supply chain risk mitigation through the sharing of information, this paper discusses the results of an empirical study conducted with manufacturing supply chain professionals. The study examines state-of-the-art challenges to managing risk in today's supply chains by reporting on data collected in 2021. To develop a rich picture of the challenges of information sharing in multi-tier supply chains, the authors adopted a qualitative research design. The authors conducted 14 interviews with supply chain professionals and ran two focus groups that were industry specific: one focused on the nuclear industry and the other on automotive. The study identifies contemporary practical challenges to information sharing in supply chains – specifically challenges related to data quality and the acceptance of sub-optimal normative supply chain practices, which have consequences for supplier assurance fatigue and supply chain transparency. The topical and contemporary study shows how an acceptance of the normative practices of a supply chain can have a cumulative effect on the likelihood of supply chain disruption due to shortcomings in approaches to information sharing. The notion of the acceptance of the status quo in this context has received limited research attention, and hence offers an extension to current discourse on supply chain risk and resilience

Circle formation by asynchronous opaque robots on infinite grid

This paper presents a distributed algorithm for circle formation problem under the infinite grid environment by asynchronous mobile opaque robots. Initially all the robots are acquiring distinct positions and they have to form a circle over the grid. Movements of the robots are restricted only along the grid lines. They do not share any global co-ordinate system. Robots are controlled by an asynchronous adversarial scheduler that operates in Look-Compute-Move cycles. The robots are indistinguishable by their nature, do not have any memory of their past configurations and previous actions. We consider the problem under luminous model, where robots communicate via lights, other than that they do not have any external communication system. Our protocol solves the  circle formation problem using seven colors. A subroutine of our algorithm also solves the line formation problem using three colors

Race, Crime, and Institutional Design

Minorities are gravely overrepresented in every stage of the criminal process--from pedestrian and automobile stops, to searches and seizures, to arrests and convictions, to incarceration and capital punishment. While racial data can provide a snapshot of the current state of affairs, such information rarely satisfies questions of causation, and usually only sets the scene for normative theory

Effective signage system

In this modern growing world, communication fills an important part of our life. Not only used to convey our feelings, communications also play a vital role in our day to day activities. One of them is “SIGNAGE SYSTEM”. These are visually oriented communication and information system consisting of maps, signs, arrows, colour coding systems, gestures, pictograms and different typographic elements. These generally differ from other methods of information because they are used typically as a guide for people’s passage through the physical world. Moreover being a system, it is a collection of correlated signs used with a coherent design and purpose for e.g.:- road signs on a highway, overhead signs in airport, signs of hospital and college, different department Signs in hospital or college. Thus understanding the importance of signage system, it is important that the coherency of the system should be intact and harnessed for better results. This is the motivating factor towards a world of effective signage system, where the signs of a particular system convey information with utmost ease and more over the coherency is maintained

Distributed Systems and Mobile Computing

The book is about Distributed Systems and Mobile Computing. This is a branch of Computer Science devoted to the study of systems whose components are in different physical locations and have limited communication capabilities. Such components may be static, often organized in a network, or may be able to move in a discrete or continuous environment. The theoretical study of such systems has applications ranging from swarms of mobile robots (e.g., drones) to sensor networks, autonomous intelligent vehicles, the Internet of Things, and crawlers on the Web. The book includes five articles. Two of them are about networks: the first one studies the formation of networks by agents that interact randomly and have the ability to form connections; the second one is a study of clustering models and algorithms. The three remaining articles are concerned with autonomous mobile robots operating in continuous space. One article studies the classical gathering problem, where all robots have to reach a common location, and proposes a fast algorithm for robots that are endowed with a compass but have limited visibility. The last two articles deal with the evacuations problem, where two robots have to locate an exit point and evacuate a region in the shortest possible time