Scott Kirkpatrick

• Hebrew University of Jerusalem

The maximum independent set problem is a classic and fundamental combinatorial challenge, where the objective is to find the largest subset of vertices in a graph such that no two vertices are adjacent. In this paper, we introduce a novel linear prioritized local algorithm tailored to address this problem on random d-regular graphs with a small and...

Finding a Maximum Clique is a classic property test from graph theory; find any one of the largest complete subgraphs in an Erdös-Rényi G(N, p) random graph. We use Maximum Clique to explore the structure of the problem as a function of N, the graph size, and K, the clique size sought. It displays a complex phase boundary, a staircase of steps at e...

Finding a Maximum Clique is a classic property test from graph theory; find any one of the largest complete subgraphs in an Erd{\"o}s-R{\'e}nyi $G(N,p)$ random graph. It is the simplest of many such problems in which algorithms requiring only a small power of $N$ steps cannot reach solutions which probabilistic arguments show must exist, exposing a...

In this paper, we present a prioritized local algorithm that computes a maximal independent set on a random d-regular graph with small and fixed connectivity d. Combining different strategies, we compute new lower bounds on the independence ratio ∀d ∈ [5, 100], d ∈ N. All the new bounds improve upon the best previous bounds. Moreover, for independe...

We explore the potential of crowd-sourced information on human mobility and activities in an urban population drawn from a significant fraction of smartphones in the Los Angeles basin during February-May 2015. The raw dataset was collected by WeFi, a smartphone app provider. The dataset is noisy, irregular, and lean; however, it is large scale (ove...

All the content consumed by mobile users, be it a web page or a live stream, undergoes some processing along the way; as an example, web pages and videos are transcoded to fit each device's screen. The recent multi-access edge computing (MEC) paradigm envisions performing such processing within the cellular network, as opposed to resorting to a clo...

All the content consumed by mobile users, be it a web page or a live stream, undergoes some processing along the way; as an example, web pages and videos are transcoded to fit each device's screen. The recent multi-access edge computing (MEC) paradigm envisions performing such processing within the cellular network, as opposed to resorting to a clo...

The MaxClique problem, finding the maximum complete subgraph in an E-R $G(N,p)$ random graph in the large $N$ limit, is a very early example of a simple problem for which finding any approximate solution within a factor of $2$ of the known, probabilistically determined limit, appears to require P$=$NP. This type of search has practical importance i...

Smartphone apps provide a vitally important opportunity for monitoring human mobility, human experience of ubiquitous information aids, and human activity in our increasingly well-instrumented spaces. As wireless data capabilities move steadily up in performance, from 2&3G to 4G (today's LTE) and 5G, it has become more important to measure human ac...

Deployment and demand traces are a crucial tool to study today's LTE systems, as well as their evolution toward 5G. In this paper, we use a set of real-world, crowdsourced traces, coming from the WeFi and OpenSignal apps, to investigate how present-day networks are deployed, and the load they serve. Given this information, we present a way to gener...

Deployment and demand traces are a crucial tool to study today's LTE systems, as well as their evolution toward 5G. In this paper, we use a set of real-world, crowdsourced traces, coming from the WeFi and OpenSignal apps, to investigate how present-day networks are deployed, and the load they serve. Given this information, we present a way to gener...

We focus on today's LTE systems and use real-world, crowdsourced traces to understand (i) how present-day LTE networks are deployed and to which extent they are suited to the current traffic load; (ii) how well they will withstand the traffic demand forecasted within 2020; (iii) which techniques to improve them should be pursued and how aggressivel...

The emergence of in-vehicle entertainment systems and self-driving vehicles, and the latters' need for high-resolution, up-to-date maps, will bring a further increase in the amount of data vehicles consume. Considering how difficult Wi-Fi offloading in vehicular environments is, the bulk of this additional load will be served by cellular networks....

Virtually all of the rapidly increasing data traffic consumed by mobile users requires some kind of processing, normally performed at cloud servers. A recent thrust, mobile edge computing, moves such processing to servers within the cellular mobile network. The large temporal and spatial variations to which mobile data usage is subject could make t...

Virtually all of the rapidly increasing data traffic consumed by mobile users requires some kind of processing, normally performed at cloud servers. A recent thrust, {\em mobile edge computing}, moves such processing to servers {\em within} the cellular mobile network. The large temporal and spatial variations to which mobile data usage is subject...

The emergence of in-vehicle entertainment systems and self-driving vehicles, and the latter's need for high-resolution, up-to-date maps, will bring a further increase in the amount of data vehicles consume. Considering how difficult WiFi offloading in vehicular environments is, the bulk of this additional load will be served by cellular networks. C...

LTE networks are commonplace nowadays; however, comparatively little is known about where (and why) they are deployed, and the demand they serve. We shed some light on these issues through large-scale, crowd-sourced measurement. Our data, collected by users of the WeFi app, spans multiple operators and multiple cities, allowing us to observe a wide...

Vehicular users are expected to consume large amounts of data, for both entertainment and navigation purposes. This will put a strain on cellular networks, which will be able to cope with such a load only if proper caching is in place, this in turn begs the question of which caching architecture is the best-suited to deal with vehicular content con...

Vehicular users are expected to consume large amounts of data, for both entertainment and navigation purposes. This will put a strain on cellular networks, which will be able to cope with such a load only if proper caching is in place, this in turn begs the question of which caching architecture is the best-suited to deal with vehicular content con...

In communications, the obstacle to high bandwidth and reliable transmission is usually the interconnections, not the links. Nowhere is this more evident than on the Internet, where broadband connections to homes, offices and now mobile smart phones are a frequent source of frustration, and the interconnections between the roughly 50 000 subnetworks...

This deliverable presents a roadmap for Future Internet Research and Experimentation (FIRE) within the Horizon 2020 program. The objective of the roadmap is to identify how FIRE can move forward via a series of key developments and milestones to achieve the advancements in testbed facilities and services that will create state of the art ecosystem...

The over-all mission of the AmpliFIRE Support Action is to support the FIRE Community to prepare FIRE for 2020, by strengthening the exploitation and impact creation capacities of Future Internet Research and Experimentation (FIRE) facilities. AmpliFIRE vision for year 2020, setting out a transition path from the current situation towards a “FIRE E...

Pythia is a prototype hybrid Mobile/Cloud service to ascertaining what the user of a mobile phone is currently doing. The service continuously captures and uploads context data to an analysis engine in the cloud. Early field testing showed that the service can categorize activities into working, at home, traveling, or shopping.

Smartphone sensors must supplement GPS if we are to provide localized services in indoor public spaces. We learn the loca;on of a user based on a known star;ng posi;on, and sensor readings from a smartphone. We use training routes labeled with the GPS loca;ons to learn a model that es;mates the user’s trajectory from the sensor readings.

Network theory has become one of the most visible theoretical frameworks that can be applied to the description, analysis, understanding, design and repair of multi-level complex systems. Complex networks occur everywhere, in man-made and human social systems, in organic and inorganic matter, from nano to macro scales, and in natural and anthropoge...

The networks formed from the links between telephones observed in a month's call detail records (CDRs) in the UK are analyzed, looking for the characteristics thought to identify a communications network or a social network. Some novel methods are employed. We find similarities to both types of network. We conclude that, just as analogies to spin g...

This paper describes the Amazon-on-Earth project that enables users to look for, navigate to and find objects of interest inside a physical space. We implemented a working prototype system in one of the libraries on our campus and ran a user study to see if there was any advantage to using the system relative to the existing library information ser...

Organizations like the Internet Archive have been capturing Web contents over decades, building up huge repositories of time-versioned pages. The timestamp annotations and the sheer volume of multi-modal content constitutes a gold mine for analysts of all sorts, across different application areas, from political analysts and marketing agencies to a...

Analysis of an unusually detailed telephone call data set --- a month of nearly all mobile and landline phone calls placed during August 2005 the United Kingdom --- allows us to identify several different types of social networks that are formed, and relate them to different activities that generate them. We distinguish, among others, work-related...

In this paper, we describe the Smart Profile Management application that was designed to help minimize mobile phone disruptions. The system does this by making phone profile changes depending on the type and content of calendar entries it sees as well as an analysis of past usage history. A prototype was developed in Python for S60 and an informal...

The Internet Archive is a live production system support- ing close to a petabyte of data and delivering an average of 2.3Gb/sec of data to Internet users. We describe the archi- tecture of this system with an emphasis on its robustness and how it is managed by a very small team of systems personnel. Notably, the current system does not employ a ca...

The EVERGROW project, and especially the DIMES distributed internet measurement tools, created under EC sponsorship in 2004-2007, give us a wealth of new information about the structure and evolution of the Internet, at its physical layer - the wires (and wireless links) that carry messages and files around the world. Some interesting insights into...

We study a map of the Internet (at the autonomous systems level), by introducing and using the method of k-shell decomposition and the methods of percolation theory and fractal geometry, to find a model for the structure of the Internet. In particular, our analysis uses information on the connectivity of the network shells to separate, in a unique...

Understanding the detailed behavior of an operating system is crucial for making informed design decisions. But such an understanding is very hard to achieve, due to the increasing complexity of such systems and the fact that they are implemented and maintained by large and diverse groups of developers. Tools like KLogger — presented in this paper...

Understanding the detailed behavior of an operating system is crucial for making informed design decisions. But such an understanding is very hard to achieve, due to the increasing complexity of such systems and the fact that they are implemented and maintained by large and diverse groups of developers. Tools like KLogger --- presented in this pape...

While the Internet is hardly "broken", it has proved unable to integrate new ideas, new architectures, and provide paths for future integration of data, voice, rich media and higher reliability. The reason is that the basic concept of the In- ternet as an end-to-end packet delivery service has made its middle layer, networking services through TCP/...

While the Internet is hardly "broken", it has proved unable to integrate new ideas, new architectures, and provide paths for future integration of data, voice, rich media and higher reliability. The reason is that the basic concept of the Internet as an end-to-end packet delivery service has made its middle layer, networking services through TCP/IP...

We have pioneered the deployment of EverLab, a production level private PlanetLab system using high-end clusters spread over Europe. EverLab supports both experimentation and computa- tional work, incorporating many of the features found on Grid systems. This paper describes the decision process that led us to choose PlanetLab and the challenges th...

Today'smodernhigh-endNetworkInterfaceCards(NICs)areequipped with an onboard CPU. In most cases, these CPU's are only used by the vendor and are operated by a proprietary OS, which makes them inaccessible to the HPC application developer. In this paper we present a design and implementation of a framework for building high-performance networking app...

We introduce and use k-shell decomposition to investigate the topology of the Internet at the AS level. Our analysis separates the Internet into three sub-components: (a) a nucleus which is a small (~100 nodes) very well connected globally distributed subgraph; (b) a fractal sub-component that is able to connect the bulk of the Internet without con...

Physical and geometrical properties are studied on self similar fractal lattices. Properties of spin systems are shown to depend on various topological factors, in addition to the fractal dimensionality. A (non random) fractal model is proposed for the backbone of the infinite cluster near percolation in d dimensions, and its properties agree with...

The k-shell decomposition of a random graph provides a different and more insightful separation of the roles of the different nodes in such a graph than does the usual analysis in terms of node degrees. We develop this approach in order to analyze the Internet’s structure at a coarse level, that of the ”Autonomous Systems” or ASes, the subnetworks...

We investigate several variants of a network creation model: a group of agents builds up a network between them while trying to keep the costs of this network small. The cost function consists of two addends, namely (i) a constant amount for each edge an agent buys and (ii) the minimum number of hops it takes sending messages to other agents. Despi...

As parallel jobs get bigger in size and finer in granularity, "system noise" is increasingly becoming a problem. In fact, fine-grained jobs on clusters with thousands of SMP nodes run faster if a processor is intentionally left idle (per node), thus enabling a separation of "system noise" from the computation. Paying a cost in average processing sp...

This work is part of our pursuit of paradigms and technical solutions that will take advantage of the rapid advances in computing power that inexpensive tools for presentation and collaborative work are bringing to the world of education. We have developed an interaction model for the "smart classroom," (more generally, for rooms in which people in...

The classic distributed computation is done by atoms, molecules or spins in vast numbers, each equipped with nothing more than the knowledge of their immediate neighborhood and the rules of statistical mechanics. These agents, 1023 or more, are able to form liquids and solids from gases, realize extremely complex ordered states, such as liquid crys...

Survey propagation is a powerful technique from statistical physics that has been applied to solve the 3-SAT problem both in principle and in practice. We give, using only probability arguments, a common derivation of survey propagation, belief propagation and several interesting hybrid methods. We then present numerical experiments which use WSAT...

We identify a wide range of human memory phenomena as potential certificates of identity. These "imprinting" behaviors are characterized by vast capacity for complex experiences, which can be recognized without apparent effort and yet cannot be transferred to others. They are suitable for use in near zero-knowledge protocols, which minimize the amo...