126 research outputs found
Claw-free t-perfect graphs can be recognised in polynomial time
A graph is called t-perfect if its stable set polytope is defined by
non-negativity, edge and odd-cycle inequalities. We show that it can be decided
in polynomial time whether a given claw-free graph is t-perfect
An Architecture for a Mobile and Dynamically Extensible Distributed DBMS
This report proposes an architectural framework for the design and implementation of a Distributed Database Management System which integrates Java and the Java Runtime Environment with the static set of operations found in a traditional database execution engine. With such a system, we intend to study the benefits of mobility of DBMS code (functionality shipping). This functionality shipping occurs at several levels, namely the query (i.e. predicates), executor (i.e. join operator) and access methods (i.e. index scan) levels
Distributed, end-to-end verifiable, and privacy-preserving internet voting systems
We present the D-DEMOS suite of distributed, privacy-preserving, and end-to-end verifiable e-voting systems; one completely asynchronous and one with minimal timing assumptions but better performance. Their distributed voting operation is human verifiable; a voter can vote over the web, using an unsafe web client stack, without sacrificing her privacy, and get recorded-as-cast assurance. Additionally, a voter can outsource election auditing to third parties, still without sacrificing privacy. We provide a model and security analysis of the systems, implement prototypes of the complete systems, measure their performance experimentally, demonstrate their ability to handle large-scale elections, and demonstrate the performance trade-offs between the two versions
Stable Sets in {ISK₄,wheel}-Free Graphs
An ISK4 in a graph G is an induced subgraph of G that is isomorphic to a subdivision of K₄ (the complete graph on four vertices). A wheel is a graph that consists of a chordless cycle, together with a vertex that has at least three neighbors in the cycle. A graph is {ISK₄,wheel}-free if it has no ISK₄ and does not contain a wheel as an induced subgraph. We give an O(|V(G)|⁷)-time algorithm to compute the maximum weight of a stable set in an input weighted {ISK₄,wheel}-free graph G with non-negative integer weights
An introduction to Graph Data Management
A graph database is a database where the data structures for the schema
and/or instances are modeled as a (labeled)(directed) graph or generalizations
of it, and where querying is expressed by graph-oriented operations and type
constructors. In this article we present the basic notions of graph databases,
give an historical overview of its main development, and study the main current
systems that implement them
D-DEMOS: A Distributed, End-to-End Verifiable, Internet Voting System
E-voting systems have emerged as a powerful technology for improving
democracy by reducing election cost, increasing voter participation, and even
allowing voters to directly verify the entire election procedure. Prior
internet voting systems have single points of failure, which may result in the
compromise of availability, voter secrecy, or integrity of the election
results. In this paper, we present the design, implementation, security
analysis, and evaluation of D-DEMOS, a complete e-voting system that is
distributed, privacy-preserving and end-to-end verifiable. Our system includes
a fully asynchronous vote collection subsystem that provides immediate
assurance to the voter her vote was recorded as cast, without requiring
cryptographic operations on behalf of the voter. We also include a distributed,
replicated and fault-tolerant Bulletin Board component, that stores all
necessary election-related information, and allows any party to read and verify
the complete election process. Finally, we also incorporate trustees, i.e.,
individuals who control election result production while guaranteeing privacy
and end-to-end-verifiability as long as their strong majority is honest. Our
system is the first e-voting system whose voting operation is human verifiable,
i.e., a voter can vote over the web, even when her web client stack is
potentially unsafe, without sacrificing her privacy, and still be assured her
vote was recorded as cast. Additionally, a voter can outsource election
auditing to third parties, still without sacrificing privacy. Finally, as the
number of auditors increases, the probability of election fraud going
undetected is diminished exponentially. We provide a model and security
analysis of the system. We implement a prototype of the complete system, we
measure its performance experimentally, and we demonstrate its ability to
handle large-scale elections.Comment: 17 pages, 5 figure
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