CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications

Paris, France

CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications

Paris, France
SEARCH FILTERS
Time filter
Source Type

Gregory S.D.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications | Bradshaw C.J.A.,University of Adelaide | Bradshaw C.J.A.,South Australian Research And Development Institute | Brook B.W.,University of Adelaide | Courchamp F.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications
Ecology | Year: 2010

Extensive theoretical work on demographic Allee effects has led to the latent assumption that they are ubiquitous in natural populations, yet current empirical support for this phenomenon is sparse. We extended previous single-taxon analyses to evaluate the empirical support for demographic Allee effects in the per capita population growth, rate of 1198 natural populations spanning all major taxa. For each population, we quantified the empirical support for five population growth models: no growth (random walk); exponential growth, with and without an Allee effect; and logistic growth, with and without an Allee effect. We used two metrics to quantify empirical support, information-theoretic and Bayesian strength of evidence, and observed top-rank frequency. The Ricker logistic model was both the most supported and most frequently top-ranked model, followed by random walk. Allee models had a combined relative support of 12.0% but were top-ranked in only 1.1 % of the time series. Accounting for local climate variation and measurement error caused the loss of topranked Allee models, although the latter also increased their relative support. The 13 time series exhibiting Allee models were shorter and less variable than other time series, although only three were non-trending. Time series containing observations at low abundance were not more likely and did not show higher support for Allee effect models. We conclude that there is relatively high potential for demographic Allee effects in these 1198 time series but comparatively few observed cases, perhaps due to the influences of climate and measurement error. © 2010 by the Ecological Society of America.


Fournier H.,University Paris Diderot | Fournier H.,French National Center for Scientific Research | Perifel S.,University Paris Diderot | Perifel S.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications | De Verclos R.,ENS Lyon
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

We consider the problem of fixed-polynomial lower bounds on the size of arithmetic circuits computing uniform families of polynomials. Assuming the Generalised Riemann Hypothesis (GRH), we show that for all k, there exist polynomials with coefficients in MA having no arithmetic circuits of size O(nk) over ℂ (allowing any complex constant). We also build a family of polynomials that can be evaluated in AM having no arithmetic circuits of size O(nk). Then we investigate the link between fixed-polynomial size circuit bounds in the Boolean and arithmetic settings. In characteristic zero, it is proved that NP ⊄ size(nk), or MA ⊂ size(n k), or NP = MA imply lower bounds on the circuit size of uniform polynomials in n variables from the class VNP over ℂ, assuming GRH. In positive characteristic p, uniform polynomials in VNP have circuits of fixed-polynomial size if and only if both VP = VNP over double-struck F p and ModpP has circuits of fixed-polynomial size. © 2013 Springer-Verlag.


Frougny C.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications | Klouda K.,Czech Technical University
Acta Polytechnica | Year: 2013

Two infinite words that are connected with some significant univoque numbers are studied. It is shown that their factor and palindromic complexities almost coincide with the factor and palindromic complexities of the famous Thue-Morse word. © Czech Technical University in Prague, 2013.


Choffrut C.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications | Malcher A.,Justus Liebig University | Mereghetti C.,University of Milan | Palano B.,University of Milan
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

The characterization of the class of FO[∈+∈]-definable languages by some generating or recognizing device is still an open problem. We prove that, restricted to bounded languages, this class coincides with the class of semilinear languages. We also study some closure properties of FO[∈+∈]-definable languages which, as a by-product, allow us to give an alternative proof that the Dyck languages cannot be defined in FO[∈+∈]. © 2010 Springer-Verlag Berlin Heidelberg.


Choffrut C.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications | Malcher A.,Justus Liebig University | Mereghetti C.,University of Milan | Palano B.,University of Milan
Acta Informatica | Year: 2012

The characterization of the class of FO[+]-definable languages by some generating or recognizing device is still an open problem. We prove that, restricted to word bounded languages, this class coincides with the class of semilinear languages. We also study the closure properties of the classes of languages definable in FO[+1], FO[<], FO[+] and FOC[+] under the main classical operations. © 2012 Springer-Verlag.


Delporte-Gallet C.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications | Devismes S.,CNRS Verimag Laboratory | Fauconnier H.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications
Journal of Parallel and Distributed Computing | Year: 2010

This article deals with stabilization and fault-tolerance. We consider two types of stabilization: the self- and pseudo-stabilization. Our goal is to implement the self- and/or pseudo-stabilizing leader election in systems with process crashes, weak reliability, and synchrony assumptions. We try to propose, when it is possible, communication-efficient implementations. Our approach allows to obtain algorithms that tolerate both transient and crash failures. Note that some of our solutions are adapted from existing fault-tolerant algorithms. The motivation here is not to propose new algorithms but merely to show some assumptions required to obtain stabilizing leader elections in systems with crash failures. In particular, we focus on the borderline assumptions where we go from the possibility to have self-stabilizing solutions to the possibility to only have pseudo-stabilizing ones. © 2009 Elsevier Inc. All rights reserved.


Cegielski P.,CNRS Complex and Logical Algorithm Laboratory | Guessarian I.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

We compare the control structures of Abstract State Machines (in short ASM) defined by Yuri Gurevich and AsmL, a language implementing it. AsmL is not an algorithmically complete language, as opposed to ASM, but it is closer to usual programming languages allowing until and while iterations and sequential composition. We here give a formal definition of AsmL, its semantics, and we construct, for each AsmL program Π, a normal form (which is an ASM program) Π n computing the same function as Π. The number of comparisons and updates during the execution of the normal form is at most three times the number of comparisons and updates in the original program. © 2010 Springer-Verlag Berlin Heidelberg.


Cegielski P.,CNRS Complex and Logical Algorithm Laboratory | Grigorieff S.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications | Guessarian I.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015

Various problems on integers lead to the class of functions defined on a ring of numbers (or a subset of such a ring) and verifying a−b divides f(a)−f(b) for all a, b.We say that such functions are “congruence preserving”. In previous works, we characterized these classes of functions for the cases ℕ → ℤ, ℤ → ℤ and ℤ/nℤ → ℤ/mℤ in terms of sums series of rational polynomials (taking only integral values) and the function giving the least common multiple of 1, 2,..., k. In this paper we relate the finite and infinite cases via a notion of “lifting”: if π: X → Y is a surjective morphism and f is a function Y → Y a lifting of f is a function F: X → X such that π ◦ F = f ◦ π. We prove that the finite case ℤ/nℤ → ℤ/nℤ can be so lifted to the infinite cases ℕ → ℕ and ℤ → ℤ. We also use such liftings to extend the characterization to the rings of p-adic and profinite integers, using Mahler representation of continuous functions on these rings. © Springer International Publishing Switzerland 2015.


Cegielski P.,CNRS Complex and Logical Algorithm Laboratory | Grigorieff S.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications | Guessarian I.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

Various problems lead to the same class of functions from integers to integers: functions having integral difference ratio, i.e. verifying f(a) − f(b) ≡ 0 (mod (a − b)) for all a > b. In this paper we characterize this class of functions from Z to Z via their `a la Newton series expansions on a suitably chosen basis of polynomials (with rational coefficients). We also exhibit an example of such a function which is not polynomial but Bessel like. © Springer International Publishing Switzerland 2014.


Choffrut C.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications | Grigorieff S.,CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015

We compare the monadic second-order theory of an arbitrary linear ordering L with the theory of the family of subsets of L endowed with the operation on subsets obtained by lifting the max operation on L. We show that the two theories define the same relations. The same result holds when lifting the min operation or both max and min operations. © Springer International Publishing Switzerland 2015.

Loading CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications collaborators
Loading CNRS Laboratory of Algorithmic Informatics: Fundamentals and Applications collaborators