pinecone/core-2020-05-10-deduplication huggingface dataset:
Optimal parameterized algorithms for planar facility location problems using Voronoi diagrams

We study a general family of facility location problems de-\ud
�ned on planar graphs and on the 2-dimensional plane. In these problems,\ud
a subset of\ud
k\ud
objects has to be selected, satisfying certain packing (dis-\ud
jointness) and covering constraints. Our main result is showing that, for\ud
each of these problems, the\ud
n\ud
O\ud
(\ud
k\ud
)\ud
time brute force algorithm of selecting\ud
k\ud
objects can be improved to\ud
n\ud
O\ud
(\ud
p\ud
k\ud
)\ud
time. The algorithm is based on\ud
focusing on the Voronoi diagram of a hypothetical solution of\ud
k\ud
objects;\ud
this idea was introduced recently in the design of geometric QPTASs, but\ud
was not yet used for exact algorithms and for planar graphs. As concrete\ud
consequences of our main result, we obtain\ud
n\ud
O\ud
(\ud
p\ud
k\ud
)\ud
time algorithms for the\ud
following problems:\ud
d\ud
-Scattered Set\ud
in planar graphs (�nd\ud
k\ud
vertices\ud
at  pairwise  distance\ud
d\ud
);\ud
d\ud
-Dominating Set\ud
/(\ud
k; d\ud
)\ud
-Center\ud
in  planar\ud
graphs (�nd\ud
k\ud
vertices such that every vertex is at distance at most\ud
d\ud
from these vertices); select\ud
k\ud
pairwise disjoint connected vertex sets from\ud
a given collection; select\ud
k\ud
pairwise disjoint disks in the plane (of possibly\ud
di�erent radii) from a given collection; cover a set of points in the plane\ud
by selecting\ud
k\ud
disks/axis-parallel squares from a given collection. We\ud
complement  these  positive  results  with  lower  bounds  suggesting  that\ud
some similar, but slightly more general problems (such as covering points\ud
with axis-parallel rectangles) do not admit\ud
n\ud
O\ud
(\ud
p\ud
k\ud
)\ud
time algorithms
Trip-Based Public Transit Routing

We study the problem of computing all Pareto-optimal journeys in a public
transit network regarding the two criteria of arrival time and number of
transfers taken. We take a novel approach, focusing on trips and transfers
between them, allowing fine-grained modeling. Our experiments on the
metropolitan network of London show that the algorithm computes full 24-hour
profiles in 70 ms after a preprocessing phase of 30 s, allowing fast queries in
dynamic scenarios.Comment: Minor corrections, no substantial changes. To be presented at ESA
  201
Logic and/of truthmaking

The purpose of this paper is to explore the question of how truthmaker theorists ought to think about their subject in relation to logic. Regarding logic and truthmaking, I defend the view that considerations drawn from advances in modal logic have little bearing on the legitimacy of truthmaker theory. To do so, I respond to objections Timothy Williamson has lodged against truthmaker theory. As for the logic of truthmaking, I show how the project of understanding the logical features of the truthmaking relation has led to an apparent impasse. I offer a new perspective on the logic of truthmaking that both explains the problem and offers a way out.postprin
Learning probability distributions generated by finite-state machines

We review methods for inference of probability distributions generated by probabilistic automata and related models for sequence generation. We focus on methods that can be proved to learn in the inference\ud
in the limit and PAC formal models. The methods we review are state merging and state splitting methods for probabilistic deterministic automata and the recently developed spectral method for nondeterministic probabilistic automata. In both cases, we derive them from a high-level algorithm described in terms of the Hankel matrix of the distribution to be learned, given as an oracle, and then describe how to adapt that algorithm to account for the error introduced by a finite sample.Peer ReviewedPostprint (author's final draft
The Relative Lyapunov Indicators: Theory and\ud
Application to Dynamical Astronomy

A recently introduced chaos detection method, the Relative Lyapunov Indicator\ud
(RLI) is investigated in the cases of symplectic mappings and continuous\ud
Hamiltonian systems. It is shown that the RLI is an efficient numerical tool in determining\ud
the true nature of individual orbits, and in separating ordered and chaotic\ud
regions of the phase space of dynamical systems. A comparison between the RLI\ud
and some other variational indicators are presented, as well as the recent applications\ud
of the RLI to various problems of dynamical astronomy
The Combinatorial World (of Auctions) According to GARP

Revealed preference techniques are used to test whether a data set is
compatible with rational behaviour. They are also incorporated as constraints
in mechanism design to encourage truthful behaviour in applications such as
combinatorial auctions. In the auction setting, we present an efficient
combinatorial algorithm to find a virtual valuation function with the optimal
(additive) rationality guarantee. Moreover, we show that there exists such a
valuation function that both is individually rational and is minimum (that is,
it is component-wise dominated by any other individually rational, virtual
valuation function that approximately fits the data). Similarly, given upper
bound constraints on the valuation function, we show how to fit the maximum
virtual valuation function with the optimal additive rationality guarantee. In
practice, revealed preference bidding constraints are very demanding. We
explain how approximate rationality can be used to create relaxed revealed
preference constraints in an auction. We then show how combinatorial methods
can be used to implement these relaxed constraints. Worst/best-case welfare
guarantees that result from the use of such mechanisms can be quantified via
the minimum/maximum virtual valuation function
On Existence and Properties of Approximate Pure Nash Equilibria in
  Bandwidth Allocation Games

In \emph{bandwidth allocation games} (BAGs), the strategy of a player
consists of various demands on different resources. The player's utility is at
most the sum of these demands, provided they are fully satisfied. Every
resource has a limited capacity and if it is exceeded by the total demand, it
has to be split between the players. Since these games generally do not have
pure Nash equilibria, we consider approximate pure Nash equilibria, in which no
player can improve her utility by more than some fixed factor $\alpha$ through
unilateral strategy changes. There is a threshold $\alpha_\delta$ (where
$\delta$ is a parameter that limits the demand of each player on a specific
resource) such that $\alpha$-approximate pure Nash equilibria always exist for
$\alpha \geq \alpha_\delta$, but not for $\alpha < \alpha_\delta$. We give both
upper and lower bounds on this threshold $\alpha_\delta$ and show that the
corresponding decision problem is ${\sf NP}$-hard. We also show that the
$\alpha$-approximate price of anarchy for BAGs is $\alpha+1$. For a restricted
version of the game, where demands of players only differ slightly from each
other (e.g. symmetric games), we show that approximate Nash equilibria can be
reached (and thus also be computed) in polynomial time using the best-response
dynamic. Finally, we show that a broader class of utility-maximization games
(which includes BAGs) converges quickly towards states whose social welfare is
close to the optimum
Further Results on Capacitated Network Design Games

In a capacitated network design game, each of n players selects\ud
a path from her source to her sink. The cost of each edge is shared\ud
equally among the players using the edge. Every edge has a finite capacity\ud
that limits the number of players using the edge. We study the\ud
price of stability for such games with respect to the max-cost objective,\ud
i.e., the maximum cost paid by any player. We show that the price of\ud
stability is O(n) for symmetric games, and this bound is tight. Furthermore,\ud
we show that the price of stability for asymmetric games can be\ud
Ω(n log n), matching the previously known upper bound. We also prove\ud
that the convergence time of best response dynamics cannot be bounded\ud
by any function of n.Peer-reviewedPost-printSAGT 2015, Saarbrücke
A poor man's epistemic logic based on propositional assignment and higher-order observation

We introduce a dynamic epistemic logic that is based on what an agent can observe, including joint observation and observation of what other agents observe. This generalizes van der Hoek, Wooldridge and colleague’s logics ECL-PC(PO) and LRC where it is common knowledge which propositional variables each agent observes. In our logic, facts of the world and their observability can both be modified by assignment programs. We show how epistemic operators can be interpreted in this framework and identify the conditions under which the principles of positive and negative introspection are valid. We also provide a sound and complete axiomatization and prove that the satisfiability problem is PSpace-complete. Finally, we show how public and private announcements can be expressed and illustrate the latter by the gossip spreading problem
Automatic Deployment of Services in the Cloud with Aeolus Blender

International audienceWe present Aeolus Blender (Blender in the following), a software product for the automatic deployment and configuration of complex service-based, distributed software systems in the " cloud ". By relying on a configuration optimiser and a deployment planner, Blender fully automates the deployment of real-life applications on OpenStack cloud deployments , by exploiting a knowledge base of software services provided by the Mandriva Armonic tool suite. The final deployment is guaranteed to satisfy not only user requirements and relevant software dependencies , but also to be optimal with respect to the number of used virtual machines
Modelling and Analysis Mobile Systems Using �pi-calculus (EFCP)

Reference passing systems, like mobile and recon�gurable\ud
systems are common nowadays. The common feature of such systems is the possibility to form dynamic logical connections between the individual modules. However, such systems are very di�cult to verify, as their logical structure is dynamic. Traditionally, decidable fragments of pi-calculus, e.g. the well-known Finite Control Processes (FCP), are used for formal modelling of reference passing systems. Unfortunately, FCPs allow only `global' concurrency between processes, and thus cannot naturally express scenarios involving `local' concurrency inside a process, such as multicast. In this paper we propose Extended Finite Control Processes (EFCP), which are more convenient for practical modelling. Moreover, an almost linear translation of EFCPs to FCPs is developed,\ud
which enables e�cient model checking of EFCPs
Specifying Concurrent Problems: Beyond Linearizability and up to Tasks
 : 
(Extended Abstract)

International audienceTasks and objects are two predominant ways of specifying distributed problems. A task specifies for each set of processes (which may run concurrently) the valid outputs of the processes. An object specifies the outputs the object may produce when it is accessed sequentially. Each one requires its own implementation notion, to tell when an execution satisfies the specification. For objects linearizability is commonly used, while for tasks implementation notions are less explored. Sequential specifications are very convenient, especially important is the locality property of linearizability, which states that linearizable objects compose for free into a linearizable object. However, most well-known tasks have no sequential specification. Also, tasks have no clear locality property.The paper introduces the notion of interval-sequential object. The corresponding implementation notion of interval-linearizability generalizes linearizability. Interval-linearizability allows to specify any task. However, there are sequential one-shot objects that cannot be expressed as tasks, under the simplest interpretation of a task. The paper also shows that a natural extension of the notion of a task is expressive enough to specify any interval-sequential object
Nonuniform SINR+Voroni Diagrams are Effectively Uniform

International audienceThis paper concerns the behavior of an SINR diagram of wireless systems, composed of a set S of n stations embedded in R^d, when restricted to the corresponding Voronoi diagram imposed on S. The diagram obtained by restricting the SINR zones to their corresponding Voronoi cells is referred to hereafter as an SINR+Voronoi diagram. While uniform SINR diagrams (where all stations transmit with the same power) are simple and nicely structured (e.g., the station reception zones are convex and “fat”) [3], nonuniform SINR diagrams might be complex (e.g., the reception zones might be fractured and their boundaries might contain many singular points) [9]. In this paper, we establish the (perhaps surprising) fact that a nonuniform SINR+Voronoi diagram is topologically almost as nice as a uniform SINR diagram. In particular, it is convex and effectively fat. This holds for every power assignment, every path-loss parameter α and every dimension d ≥ 1. The convexity property also holds for every SINR threshold β > 0, and the effective fatness holds for any β > 1. These fundamental properties provide a theoretical justification to engineering practices basing zonal tessellations on the Voronoi diagram, and helps to explain the soundness and efficacy of such practices.We also consider two algorithmic applications. The first concerns the Power Control with Voronoi Diagram (PCVD) problem, where given n stations embedded in some polygon P, it is required to find the power assignment that optimizes the SINR threshold of the transmission station si for any given reception point p ∈ P in its Voronoi cell Vor(si). The second application is approximate point location; we show that for SINR+Voronoi zones, this task can be solved considerably more efficiently than in the general non-uniform case
Anonymous Graph Exploration with Binoculars

International audienceWe investigate the exploration of networks by a mobile agent. It is long known that, without global information about the graph, it is not possible to make the agent halts after the exploration except if the graph is a tree. We therefore endow the agent with binoculars, a sensing device that can show the local structure of the environment at a constant distance of the agent current location.We show that, with binoculars, it is possible to explore and halt in a large class of non-tree networks. We give a complete characterization of the class of networks that can be explored using binoculars using standard notions of discrete topology. This class is much larger than the class of trees: it contains in particular chordal graphs, plane triangulations and triangulations of the projective plane. Our characterization is constructive, we present an Exploration algorithm that is universal; this algorithm explores any network explorable with binoculars, and never halts in non-explorable networks
An adequate compositional encoding of bigraph structure in linear logic with subexponentials

International audienceIn linear logic, formulas can be split into two sets: classical (those that can be used as many times as necessary) or linear (those that are consumed and no longer available after being used). Subexponentials generalize this notion by allowing the formulas to be split into many sets, each of which can then be specified to be classical or linear. This flexibility increases its expressiveness: we already have adequate encodings of a number of other proof systems, and for computational models such as concurrent constraint programming, in linear logic with subexponentials (SEL). Bigraphs were proposed by Milner in 2001 as a model for ubiquitous computing, subsuming models of computation such as CCS and the π-calculus and capable of modeling connectivity and locality at the same time. In this work we present an encoding of the bigraph structure in SEL, thus giving an indication of the expressive power of this logic, and at the same time providing a framework for reasoning and operating on bigraphs. Our encoding is adequate and therefore the operations of composition and juxtaposition can be performed on the logical level. Moreover, all the proof-theoretical tools of SEL become available for querying and proving properties of bigraph structures
Automated Benchmarking of Incremental SAT and QBF Solvers

Incremental SAT and QBF solving potentially yields improvements when
sequences of related formulas are solved. An incremental application is usually
tailored towards some specific solver and decomposes a problem into incremental
solver calls. This hinders the independent comparison of different solvers,
particularly when the application program is not available. As a remedy, we
present an approach to automated benchmarking of incremental SAT and QBF
solvers. Given a collection of formulas in (Q)DIMACS format generated
incrementally by an application program, our approach automatically translates
the formulas into instructions to import and solve a formula by an incremental
SAT/QBF solver. The result of the translation is a program which replays the
incremental solver calls and thus allows to evaluate incremental solvers
independently from the application program. We illustrate our approach by
different hardware verification problems for SAT and QBF solvers.Comment: camera-ready version (8 pages + 2 pages appendix), to appear in the
  proceedings of the 20th International Conference on Logic for Programming,
  Artificial Intelligence and Reasoning (LPAR), LNCS, Springer, 201
On Subexponentials, Synthetic Connectives, and Multi-level Delimited Control

International audienceWe construct a partially-ordered hierarchy of delimited control operators similar to those of the CPS hierarchy of Danvy and Filinski. However, instead of relying on nested CPS translations, these operators are directly interpreted in linear logic extended with subexponentials (i.e., multiple pairs of ! and ?). We construct an independent proof theory for a fragment of this logic based on the principle of focusing. It is then shown that the new constraints placed on the permutation of cuts correspond to multiple levels of delimited control
Relational reasoning via probabilistic coupling

Probabilistic coupling is a powerful tool for analyzing pairs of
probabilistic processes. Roughly, coupling two processes requires finding an
appropriate witness process that models both processes in the same probability
space. Couplings are powerful tools proving properties about the relation
between two processes, include reasoning about convergence of distributions and
stochastic dominance---a probabilistic version of a monotonicity property.
  While the mathematical definition of coupling looks rather complex and
cumbersome to manipulate, we show that the relational program logic pRHL---the
logic underlying the EasyCrypt cryptographic proof assistant---already
internalizes a generalization of probabilistic coupling. With this insight,
constructing couplings is no harder than constructing logical proofs. We
demonstrate how to express and verify classic examples of couplings in pRHL,
and we mechanically verify several couplings in EasyCrypt
Many-to-one matchings with lower quotas : algorithms and complexity

We study a natural generalization of the maximum weight many-to-one matching problem. We are given an undirected bipartite graph G = (AUP,E) with weights on the edges in E, and with lower and upper quotas on the vertices in P. We seek a maximum weight many-toone matching satisfying two sets of constraints: vertices in A are incident to at most one matching edge, while vertices in P are either unmatched or they are incident to a number of matching edges between their lower and upper quota. This problem, which we call maximum weight many-toone matching with lower and upper quotas (wmlq), has applications to the assignment of students to projects within university courses, where there are constraints on the minimum and maximum numbers of students that must be assigned to each project. In this paper, we provide a comprehensive analysis of the complexity of wmlq from the viewpoints of classic polynomial time algorithms, fixed-parameter tractability, as well as approximability. We draw the line between NP-hard and polynomially tractable instances in terms of degree and quota constraints and provide efficient algorithms to solve the tractable ones. We further show that the problem can be solved in polynomial time for instances with bounded treewidth; however, the corresponding runtime is exponential in the treewidth with the maximum upper quota umax as basis, and we prove that this dependence is necessary unless FPT = W[1]. Finally, we also present an approximation algorithm for the general case with performance guarantee umax+1, which is asymptotically best possible unless P = NP
Minimum Degree up to Local Complementation: Bounds, Parameterized
  Complexity, and Exact Algorithms

The local minimum degree of a graph is the minimum degree that can be reached
by means of local complementation. For any n, there exist graphs of order n
which have a local minimum degree at least 0.189n, or at least 0.110n when
restricted to bipartite graphs. Regarding the upper bound, we show that for any
graph of order n, its local minimum degree is at most 3n/8+o(n) and n/4+o(n)
for bipartite graphs, improving the known n/2 upper bound. We also prove that
the local minimum degree is smaller than half of the vertex cover number (up to
a logarithmic term). The local minimum degree problem is NP-Complete and hard
to approximate. We show that this problem, even when restricted to bipartite
graphs, is in W[2] and FPT-equivalent to the EvenSet problem, which
W[1]-hardness is a long standing open question. Finally, we show that the local
minimum degree is computed by a O*(1.938^n)-algorithm, and a
O*(1.466^n)-algorithm for the bipartite graphs
Incentivizing Exploration with Heterogeneous Value of Money

Recently, Frazier et al. proposed a natural model for crowdsourced
exploration of different a priori unknown options: a principal is interested in
the long-term welfare of a population of agents who arrive one by one in a
multi-armed bandit setting. However, each agent is myopic, so in order to
incentivize him to explore options with better long-term prospects, the
principal must offer the agent money. Frazier et al. showed that a simple class
of policies called time-expanded are optimal in the worst case, and
characterized their budget-reward tradeoff.
  The previous work assumed that all agents are equally and uniformly
susceptible to financial incentives. In reality, agents may have different
utility for money. We therefore extend the model of Frazier et al. to allow
agents that have heterogeneous and non-linear utilities for money. The
principal is informed of the agent's tradeoff via a signal that could be more
or less informative.
  Our main result is to show that a convex program can be used to derive a
signal-dependent time-expanded policy which achieves the best possible
Lagrangian reward in the worst case. The worst-case guarantee is matched by
so-called "Diamonds in the Rough" instances; the proof that the guarantees
match is based on showing that two different convex programs have the same
optimal solution for these specific instances. These results also extend to the
budgeted case as in Frazier et al. We also show that the optimal policy is
monotone with respect to information, i.e., the approximation ratio of the
optimal policy improves as the signals become more informative.Comment: WINE 201