453 Works

Design and Implementation of a Concurrent Logic Programming Language with Linear Logic Constraints

Thierry Martinez
My thesis aims at designing a practical language as close as possible to the linear concurrent constraint (LCC) theory. The main contribution is a new operational semantics which behaves as an angelic scheduler with a tractable algorithmic complexity. This operational semantics is sound and complete with respect to the logical semantics and allows the construction of a rich language over a very simple kernel.

Sublinear Communication Protocols for Multi-Party Pointer Jumping and a Related Lower Bound

Joshua Brody & Amit Chakrabarti
We study the one-way number-on-the-forehead (NOF) communication complexity of the $k$-layer pointer jumping problem with $n$ vertices per layer. This classic problem, which has connections to many aspects of complexity theory, has seen a recent burst of research activity, seemingly preparing the ground for an $Omega(n)$ lower bound, for constant $k$. Our first result is a surprising sublinear --- i.e., $o(n)$ --- upper bound for the problem that holds for $k ge 3$, dashing hopes...

The Complexity of Integrating Routing Decisions in Public Transportation Models

Marie Schmidt & Anita Schöbel
To model and solve optimization problems arising in public transportation, data about the passengers is necessary and has to be included in the models in any phase of the planning process. Many approaches assume a two-step procedure: in a first step, the data about the passengers is distributed over the public transportation network using traffic-assignment procedures. In a second step, the actual planning of lines, timetables, etc. takes place. This approach ignores that for most...

Relating two standard notions of secrecy

Eugen Zalinescu, Véronique Cortier & Michaël Rusinowitch
Two styles of definitions are usually considered to express that a security protocol preserves the confidentiality of a data { t s}. Reach-ability-based secrecy means that { t s} should never be disclosed while equi-valence-based secrecy states that two executions of a protocol with distinct instances for { t s} should be indistinguishable to an attacker. Although the second formulation ensures a higher level of security and is closer to cryptographic notions of secrecy, decidability...

Model-Based Visualization for Intervention Planning

Bernhard Preim
Computer support for intervention planning is often a two-stage process: In a first stage, the relevant segmentation target structures are identified and delineated. In a second stage, image analysis results are employed for the actual planning process. In the first stage, model-based segmentation techniques are often used to reduce the interaction effort and increase the reproducibility. There is a similar argument to employ model-based techniques for the visualization as well. With increasingly more visualization options,...

Two-phase Algorithms for the Parametric Shortest Path Problem

Sourav Chakraborty, Eldar Fischer, Oded Lachish & Raphael Yuster
A {\em parametric weighted graph} is a graph whose edges are labeled with continuous real functions of a single common variable. For any instantiation of the variable, one obtains a standard edge-weighted graph. Parametric weighted graph problems are generalizations of weighted graph problems, and arise in various natural scenarios. Parametric weighted graph algorithms consist of two phases. A {\em preprocessing phase} whose input is a parametric weighted graph, and whose output is a data structure,...

Place-Boundedness for Vector Addition Systems with one zero-test

Rémi Bonnet, Alain Finkel, Jérôme Leroux & Marc Zeitoun
Reachability and boundedness problems have been shown decidable for Vector Addition Systems with one zero-test. Surprisingly, place-boundedness remained open. We provide here a variation of the Karp-Miller algorithm to compute a basis of the downward closure of the reachability set which allows to decide place-boundedness. This forward algorithm is able to pass the zero-tests thanks to a finer cover, hybrid between the reachability and cover sets, reclaiming accuracy on one component. We show that this...

QoS-aware Multicommodity Flows and Transportation Planning

George Tsaggouris & Christos Zaroliagis
We consider the emph{QoS-aware Multicommodity Flow} problem, a natural generalization of the weighted multicommodity flow problem where the demands and commodity values are elastic to the Quality-of-Service characteristics of the underlying network. The problem is fundamental in transportation planning and also has important applications beyond the transportation domain. We provide a FPTAS for the QoS-aware Multicommodity Flow problem by building upon a Lagrangian relaxation method and a recent FPTAS for the non-additive shortest path problem.

Polynomial Interpretations over the Reals do not Subsume Polynomial Interpretations over the Integers

Friedrich Neurauter & Aart Middeldorp
Polynomial interpretations are a useful technique for proving termination of term rewrite systems. They come in various flavors: polynomial interpretations with real, rational and integer coefficients. In 2006, Lucas proved that there are rewrite systems that can be shown polynomially terminating by polynomial interpretations with real (algebraic) coefficients, but cannot be shown polynomially terminating using polynomials with rational coefficients only. He also proved a similar theorem with respect to the use of rational coefficients versus...

Reflections on Multivariate Algorithmics and Problem Parameterization

Rolf Niedermeier
Research on parameterized algorithmics for NP-hard problems has steadily grown over the last years. We survey and discuss how parameterized complexity analysis naturally develops into the field of multivariate algorithmics. Correspondingly, we describe how to perform a systematic investigation and exploitation of the ``parameter space'' of computationally hard problems.

Merging Techniques for Faster Derivation of WCET Flow Information using Abstract Execution

Jan Gustafsson & Andreas Ermedahl
Static Worst-Case Execution Time (WCET) analysis derives upper bounds for the execution times of programs. Such bounds are crucial when designing and verifying real-time systems. A key component in static WCET analysis is to derive flow information, such as loop bounds and infeasible paths. We have previously introduced abstract execution (AE), a method capable of deriving very precise flow information. This paper present different merging techniques that can be used by AE for trading analysis...

Towards Formally Verifiable WCET Analysis for a Functional Programming Language

Kevin Hammond, Christian Ferdinand, Reinhold Heckmann, Roy Dyckhoff, Martin Hofman, Steffen Jost, Hans-Wolfgang Loidl, Greg Michaelson, Robert Pointon, Norman Scaife, Jocelyn Sérot & Andy Wallace
This paper describes ongoing work aimed at the construction of formal cost models and analyses to yield verifiable guarantees of resource usage in the context of real-time embedded systems. Our work is conducted in terms of the domain-specific language Hume, a language that combines functional programming for computations with finitestate automata for specifying reactive systems. We outline an approach in which high-level information derived from source-code analysis can be combined with worst-case execution time information...

Efficient Minimization of DFAs with Partial Transition

Antti Valmari & Petri Lehtinen
Let PT-DFA mean a deterministic finite automaton whose transition relation is a partial function. We present an algorithm for minimizing a PT-DFA in $O(m lg n)$ time and $O(m+n+alpha)$ memory, where $n$ is the number of states, $m$ is the number of defined transitions, and $alpha$ is the size of the alphabet. Time consumption does not depend on $alpha$, because the $alpha$ term arises from an array that is accessed at random and never initialized....

Convergence Thresholds of Newton's Method for Monotone Polynomial Equations

Javier Esparza, Stefan Kiefer & Michael Luttenberger
Monotone systems of polynomial equations (MSPEs) are systems of fixed-point equations $X_1 = f_1(X_1, ldots, X_n),$ $ldots, X_n = f_n(X_1, ldots, X_n)$ where each $f_i$ is a polynomial with positive real coefficients. The question of computing the least non-negative solution of a given MSPE $vec X = vec f(vec X)$ arises naturally in the analysis of stochastic models such as stochastic context-free grammars, probabilistic pushdown automata, and back-button processes. Etessami and Yannakakis have recently adapted...

INFER: Interactive Timing Profiles based on Bayesian Networks

Michael Zolda
We propose an approach for timing analysis of software-based embedded computer systems that builds on the established probabilistic framework of Bayesian networks. We envision an approach where we take (1) an abstract description of the control flow within a piece of software, and (2) a set of run-time traces, which are combined into a Bayesian network that can be seen as an interactive timing profile. The obtained profile can be used by the embedded systems...

11. Multistage Methods for Freight Train Classification

Riko Jacob, Peter Marton, Jens Maue & Marc Nunkesser
In this paper we establish a consistent encoding of freight train classification methods. This encoding scheme presents a powerful tool for efficient presentation and analysis of classification methods, which we successfully apply to illustrate the most relevant historic results from a more theoretical point of view. We analyze their performance precisely and develop new classification methods making use of the inherent optimality condition of the encoding. We conclude with deriving optimal algorithms and complexity results...

Fast equivalence-checking for normed context-free processes

Wojciech Czerwinski & Slawomir Lasota
Bisimulation equivalence is decidable in polynomial time over normed graphs generated by a context-free grammar. We present a new algorithm, working in time $O(n^5)$, thus improving the previously known complexity $O(n^8 * polylog(n))$. It also improves the previously known complexity $O(n^6 * polylog(n))$ of the equality problem for simple grammars.

Geodesic Fréchet Distance Inside a Simple Polygon

Carola Wenk & Atlas F. Cook
We unveil an alluring alternative to parametric search that applies to both the non-geodesic and geodesic Fr{'\e}chet optimization problems. This randomized approach is based on a variant of red-blue intersections and is appealing due to its elegance and practical efficiency when compared to parametric search. We present the first algorithm for the geodesic Fr{'\e}chet distance between two polygonal curves $A$ and $B$ inside a simple bounding polygon $P$. The geodesic Fr{'\e}chet decision problem is solved...

Constraint Answer Set Programming Systems

Christian Drescher
We present an integration of answer set programming and constraint processing as an interesting approach to constraint logic programming. Although our research is in a very early stage, we motivate constraint answer set programming and report on related work, our research objectives, preliminary results we achieved, and future work.

Implementation Alternatives for Bottom-Up Evaluation

Stefan Brass
Bottom-up evaluation is a central part of query evaluation / program execution in deductive databases. It is used after a source code optimization like magic sets or SLDmagic that ensures that only facts relevant for the query can be derived. Then bottom-up evaluation simply performs the iteration of the standard TP -operator to compute the minimal model. However, there are different ways to implement bottom-up evaluation efficiently. Since this is most critical for the performance...

Improving the Efficiency of Gibbs Sampling for Probabilistic Logical Models by Means of Program Specialization

Daan Fierens
There is currently a large interest in probabilistic logical models. A popular algorithm for approximate probabilistic inference with such models is Gibbs sampling. From a computational perspective, Gibbs sampling boils down to repeatedly executing certain queries on a knowledge base composed of a static part and a dynamic part. The larger the static part, the more redundancy there is in these repeated calls. This is problematic since inefficient Gibbs sampling yields poor approximations. We show...


Christopher Lynch

Revisiting the Rice Theorem of Cellular Automata

Pierre Guillon & Gaétan Richard
A cellular automaton is a parallel synchronous computing model, which consists in a juxtaposition of finite automata whose state evolves according to that of their neighbors. It induces a dynamical system on the set of configurations, \ie the infinite sequences of cell states. The limit set of the cellular automaton is the set of configurations which can be reached arbitrarily late in the evolution. In this paper, we prove that all properties of limit sets...

PapaBench: a Free Real-Time Benchmark

Fadia Nemer, Hugues Cassé, Pascal Sainrat, Jean-Paul Bahsoun & Marianne De Michiel
This paper presents PapaBench, a free real-time benchmark and compares it with the existing benchmark suites. It is designed to be valuable for experimental works in WCET computation and may be also useful for scheduling analysis. This bench is based on the Paparazzi project that represents a real-time application, developed to be embedded on different Unmanned Aerial Vehicles (UAV). In this paper, we explain the transformation process of Paparazzi applied to obtain the PapaBench. We...

The Remote Point Problem, Small Bias Spaces, and Expanding Generator Sets

Vikraman Arvind & Srikanth Srinivasan
Using $\varepsilon$-bias spaces over $\F_2$, we show that the Remote Point Problem (RPP), introduced by Alon et al \cite{APY09}, has an $\NC^2$ algorithm (achieving the same parameters as \cite{APY09}). We study a generalization of the Remote Point Problem to groups: we replace $\F_2^n$ by $\mcG^n$ for an arbitrary fixed group $\mcG$. When $\mcG$ is Abelian we give an $\NC^2$ algorithm for RPP, again using $\varepsilon$-bias spaces. For nonabelian $\mcG$, we give a deterministic polynomial-time algorithm...

Registration Year

  • 2010

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