Results for "Christina Hedges"

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Effect of Pressure Broadening on Molecular Absorption Cross Sections in Exoplanetary AtmospheresFeb 02 2016Spectroscopic observations of exoplanets are leading to unprecedented constraints on their atmospheric compositions. However, molecular abundances derived from spectra are degenerate with the absorption cross sections which form critical input data in ... More
Discovery of New Dipper Stars with K2: A Window into the Inner Disk Region of T Tauri StarsFeb 01 2018In recent years a new class of Young Stellar Object has been defined, referred to as dippers, where large transient drops in flux are observed. These dips are too large to be attributed to stellar variability, last from hours to days and can reduce the ... More
Monad Transformers for Backtracking SearchJun 09 2014This paper extends Escardo and Oliva's selection monad to the selection monad transformer, a general monadic framework for expressing backtracking search algorithms in Haskell. The use of the closely related continuation monad transformer for similar ... More
String diagrams for game theoryMar 20 2015This paper presents a monoidal category whose morphisms are games (in the sense of game theory, not game semantics) and an associated diagrammatic language. The two basic operations of a monoidal category, namely categorical composition and tensor product, ... More
The game semantics of game theoryApr 25 2019We use a reformulation of compositional game theory to reunite game theory with game semantics, by viewing an open game as the System and its choice of contexts as the Environment. Specifically, the system is jointly controlled by $n \geq 0$ noncooperative ... More
A generalisation of Nash's theorem with higher-order functionalsJan 21 2013The recent theory of sequential games and selection functions by Mar- tin Escardo and Paulo Oliva is extended to games in which players move simultaneously. The Nash existence theorem for mixed-strategy equilibria of finite games is generalised to games ... More
Kepler-62f: Kepler's First Small Planet in the Habitable Zone, but Is It Real?May 14 2019May 15 2019Kepler-62f is the first exoplanet small enough to plausibly have a rocky composition orbiting within the habitable zone (HZ) discovered by the Kepler Mission. The planet is 1.4 times the size of the Earth and has an orbital period of 267 days. At the ... More
Oscillations and Surface Rotation of Red Giant StarsAug 03 2013More than 15000 red giants observed by Kepler for a duration of almost one year became public at the beginning of this year. We analysed a subsample of 416 stars to determine the global properties of acoustic modes (mean large separation and frequency ... More
Kepler-62f: Kepler's First Small Planet in the Habitable Zone, but Is It Real?May 14 2019Kepler-62f is the first exoplanet small enough to plausibly have a rocky composition orbiting within the habitable zone (HZ) discovered by the Kepler Mission. The planet is 1.4 times the size of the Earth and has an orbital period of 267 days. At the ... More
A Generalised Quantifier Theory of Natural Language in Categorical Compositional Distributional Semantics with BialgebrasFeb 04 2016Categorical compositional distributional semantics is a model of natural language; it combines the statistical vector space models of words with the compositional models of grammar. We formalise in this model the generalised quantifier theory of natural ... More
An $L^2-$stability estimate for periodic nonuniform sampling in higher dimensionsOct 31 2016We consider sampling strategies for a class of multivariate bandlimited functions $f$ that have a spectrum consisting of disjoint frequency bands. Taking advantage of the special spectral structure, we provide formulas relating $f$ to the samples $f(y), ... More
Barycentric subdivisions and derangement polynomials for the even-signed permutation groupsDec 06 2012Jan 21 2013The derangement polynomial for the symmetric group enumerates derangements by the number of excedances. It can be interpreted as the local $h$-polynomial, in the sense of Stanley, of the barycentric subdivision of the simplex. Motivated by this interpretation, ... More
Hamiltonicity and $σ$-hypergraphsJul 17 2014We define and study a special type of hypergraph. A $\sigma$-hypergraph $H= H(n,r,q$ $\mid$ $\sigma$), where $\sigma$ is a partition of $r$, is an $r$-uniform hypergraph having $nq$ vertices partitioned into $ n$ classes of $q$ vertices each. If the classes ... More
An extension and trace theorem for functions of H-bounded variation in Carnot groups of step 2Oct 17 2005This paper provides an extension for a function $u \in BV_H(\Omega)$ to a function $u_0 \in BV_H(G)$ when $\Omega$ is ``H-admissible,'' and G is a step 2 Carnot group. It is shown that H-admissible domains include non-characteristic domains and domains ... More
Critical random hypergraphs: The emergence of a giant set of identifiable verticesJan 16 2004Aug 30 2005We consider a model for random hypergraphs with identifiability, an analogue of connectedness. This model has a phase transition in the proportion of identifiable vertices when the underlying random graph becomes critical. The phase transition takes various ... More
Faulhaber's Problem Revisited: Alternate Methods for Deriving the Bernoulli Numbers--Part IDec 27 2018This paper sets the groundwork for the consideration of families of recursively defined polynomials and rational functions capable of describing the Bernoulli numbers. These families of functions arise from various recursive definitions of the Bernoulli ... More
Harmonic Functions on Manifolds with Nonnegative Ricci Curvature and Linear Volume GrowthMar 29 1999Lower bounds on Ricci curvature limit the volumes of sets and the existence of harmonic functions on Riemannian manifolds. In 1975, Shing Tung Yau proved that a complete noncompact manifold with nonnegative Ricci curvature has no nonconstant harmonic ... More
The Almost Rigidity of Manifolds with Lower Bounds on Ricci Curvature and Minimal Volume GrowthMar 29 1999We consider complete noncompact Riemannian manifolds with quadratically decaying lower Ricci curvature bounds and minimal volume growth. We first prove a rigidity result showing that ends with strongly minimal volume growth are isometric to warped product ... More
Maximizing Volume Ratios for Shadow Covering by TetrahedraJan 09 2012Define a body A to be able to hide behind a body B if the orthogonal projection of B contains a translation of the corresponding orthogonal projection of A in every direction. In two dimensions, it is easy to observe that there exist two objects such ... More
Intrinsic Flat Arzela-Ascoli TheoremsFeb 25 2014Jun 21 2014One of the most powerful theorems in metric geometry is the Arzela-Ascoli Theorem which provides a continuous limit for sequences of equicontinuous functions between two compact spaces. This theorem has been extended by Gromov and Grove-Petersen to sequences ... More
Explicit bounds for composite lacunary polynomialsApr 13 2017Nov 17 2017Let $f, g, h\in \mathbb{C}\left[x\right]$ be non-constant complex polynomials satisfying $f(x)=g(h(x))$ and let $f$ be lacunary in the sense that it has at most $l$ non-constant terms. Zannier proved that there exists a function $B_1(l)$ on $\mathbb{N}$, ... More
K2SUPERSTAMP: The release of calibrated mosaics for the {\em Kepler/K2} MissionFeb 18 2018We describe the release of a new High Level Science Product (HLSP) available at the MAST archive. The HLSP, called K2Superstamp, consists of a series of FITS images for four open star clusters observed by the K2 Mission using so-called "superstamp" pixel ... More
H2O abundances in the atmospheres of three hot JupitersJul 22 2014The core accretion theory for giant planet formation predicts enrichment of elemental abundances in planetary envelopes caused by runaway accretion of planetesimals, which is consistent with measured super-solar abundances of C, N, P, S, Xe, and Ar in ... More
Kepler's Discoveries Will Continue: 21 Important Scientific Opportunities with Kepler & K2 Archive DataOct 30 2018NASA's Kepler Space Telescope has collected high-precision, high-cadence time series photometry on 781,590 unique postage-stamp targets across 21 different fields of view. These observations have already yielded 2,496 scientific publications by authors ... More
Dynamic propensity in a kinetically constrained lattice gasOct 23 2006May 22 2007We apply the concept of dynamic propensity to a simple kinetically constrained model of glass formers, the two-vacancy assisted triangular lattice gas, or (2)-TLG. We find that the propensity field, defined in our case as the local root-mean square displacement ... More
A catalog of 29 open clusters and associations observed by the Kepler and K2 MissionsOct 29 2018Over the past nine years, the Kepler and K2 Missions have carried out high precision photometric monitoring of more than half a million stars. Among these targets are 29 clusters and associations, with ages from 1 Myr to over 11 Gyr. We have generated ... More
Dynamic facilitation explains democratic particle motion of metabasin transitionsJun 07 2007Jun 07 2007Transitions between metabasins in supercooled liquids seem to occur through rapid "democratic" collective particle rearrangements. Here we show that this apparent homogeneous particle motion is a direct consequence of dynamic facilitation. We do so by ... More
A Polynomial-Time Algorithm for Pliable Index CodingOct 21 2016Aug 09 2017In pliable index coding, we consider a server with $m$ messages and $n$ clients where each client has as side information a subset of the messages. We seek to minimize the number of broadcast transmissions, so that each client can recover any one unknown ... More
Smooth Convergence Away from Singular SetsFeb 04 2012Oct 02 2012We consider sequences of metrics, $g_j$, on a Riemannian manifold, $M$, which converge smoothly on compact sets away from a singular set $S\subset M$, to a metric, $g_\infty$, on $M\setminus S$. We prove theorems which describe when $M_j=(M, g_j)$ converge ... More
Electrical Networks with Prescribed Current and Applications to Random Walks on GraphsMar 07 2017Oct 14 2018We study the inverse problem of determining the conductivity matrix of an electrical network from the prescribed knowledge of the magnitude of the induced current along the edges coupled with the imposed voltage or injected current on the boundary nodes. ... More
On universal spaces for the class of Banach spaces whose dual balls are uniform Eberlein compactsMar 22 2011For k being the first uncountable cardinal w_1 or k being the cardinality of the continuum c, we prove that it is consistent that there is no Banach space of density k in which it is possible to isomorphically embed every Banach space of the same density ... More
Robustification of Elliott's on-line EM algorithm for HMMsApr 07 2013In this paper, we establish a robustification of an on-line algorithm for modelling asset prices within a hidden Markov model (HMM). In this HMM framework, parameters of the model are guided by a Markov chain in discrete time, parameters of the asset ... More
Sequences of Open Riemannian Manifolds with BoundaryJan 17 2013Jun 19 2013We consider sequences of open Riemannian manifolds with boundary that have no regularity conditions on the boundary. To define a reasonable notion of a limit of such a sequence, we examine "$\delta$ inner regions" which avoid the boundary by a distance ... More
Parking on a random treeOct 27 2016Consider a uniform random rooted tree on vertices labelled by $[n] = \{1,2,\ldots,n\}$, with edges directed towards the root. We imagine that each node of the tree has space for a single car to park. A number $m \le n$ of cars arrive one by one, each ... More
Making recommendations bandwidth awareJul 13 2016Dec 05 2017This paper asks how much we can gain in terms of bandwidth and user satisfaction, if recommender systems became bandwidth aware and took into account not only the user preferences, but also the fact that they may need to serve these users under bandwidth ... More
Efficiently Tracking Homogeneous Regions in Multichannel ImagesAug 16 2017We present a method for tracking Maximally Stable Homogeneous Regions (MSHR) in images with an arbitrary number of channels. MSHR are conceptionally very similar to Maximally Stable Extremal Regions (MSER) and Maximally Stable Color Regions (MSCR), but ... More
Nonuniform sampling and multiscale computationSep 10 2013Aug 24 2014In homogenization theory and multiscale modeling, typical functions satisfy the scaling law $f^{\epsilon}(x) = f(x,x/\epsilon)$, where $f$ is periodic in the second variable and $\epsilon$ is the smallest relevant wavelength, $0<\epsilon\ll1$. Our main ... More
Mathematical analysis of a marine ecosystem model with nonlinear coupling terms and non-local boundary conditionsMar 18 2014Aug 24 2015We investigate the weak solvability of initial boundary value problems associated with an ecosystem model of the marine phosphorus cycle. The analysis covers the model equations themselves as well as their linearization which is important in the model ... More
A Boolean algebra and a Banach space obtained by push-out iterationDec 22 2010Under the assumption that the continuum c is a regular cardinal, we prove the existence and uniqueness of a Boolean algebra B of size c defined by sharing the main structural properties that P(N)/fin has under CH and in the aleph2-Cohen model. We prove ... More
Witnessing quantum memory in non-Markovian processesNov 09 2018We present a method to detect a quantum memory in a non-Markovian process. We call a process Markovian when the environment does not provide a memory that retains correlations across consecutive system-environment interactions. We define two types of ... More
Enumeration of super-strong Wilf equivalence classes of permutations in the generalized factor orderMar 23 2018Dec 20 2018Super-strong Wilf equivalence classes of the symmetric group ${\mathcal S}_n$ on $n$ letters, with respect to the generalized factor order, were shown by Hadjiloucas, Michos and Savvidou to be in bijection with pyramidal sequences of consecutive differences. ... More
Preservation of log-concavity on summationFeb 25 2005Oct 12 2005We extend Hoggar's theorem that the sum of two independent discrete-valued log-concave random variables is itself log-concave. We introduce conditions under which the result still holds for dependent variables. We argue that these conditions are natural ... More
Hybrid matrix compression for high-frequency problemsSep 12 2018Feb 04 2019Boundary element methods for the Helmholtz equation lead to large dense matrices that can only be handled if efficient compression techniques are used. Directional compression techniques can reach good compression rates even for high-frequency problems. ... More
Global weak solutions to a strongly degenerate haptotaxis modelMar 14 2016We consider a one-dimensional version of a model obtained in [C. Engwer, A. Hunt, and C. Surulescu: Effective equations for anisotropic glioma spread with proliferation: a multiscale approach and comparisons with previous settings, IMA J. Math. Med. Biol. ... More
Parking on a random treeOct 27 2016Nov 06 2017Consider a uniform random rooted tree on vertices labelled by $[n] = \{1,2,\ldots,n\}$, with edges directed towards the root. We imagine that each node of the tree has space for a single car to park. A number $m \le n$ of cars arrive one by one, each ... More
The covering spectrum of a compact length spaceNov 22 2003We define a new spectrum for compact length spaces and Riemannian manifolds called the "covering spectrum" which roughly measures the size of the one dimensional holes in the space. More specifically, the covering spectrum is a set of real numbers $\delta>0$ ... More
A Deterministic Algorithm for Pliable Index CodingJan 21 2016Pliable index coding considers a server with m messages, and n clients where each has as side information a subset of the messages. We seek to minimize the number of transmissions the server should make, so that each client receives (any) one message ... More
Universal Covers for Hausdorff Limits of Noncompact SpacesJul 02 2002We prove that if $Y$ is the Gromov-Hausdorff limit of a sequence of complete manifolds, $M^n_i$, with a uniform lower bound on Ricci curvature then $Y$ has a universal cover.
Composite polynomials in linear recurrence sequencesOct 29 2018Let $(G_n(x))_{n=0}^\infty$ be a $d$-th order linear recurrence sequence having polynomial characteristic roots, one of which has degree strictly greater than the others. Moreover, let $m\geq 2$ be a given integer. We ask for $n\in\mathbb{N}$ such that ... More
Contrasting Various Notions of Convergence in Geometric AnalysisMar 17 2018We explore the distinctions between $L^p$ convergence of metric tensors on a fixed Riemannian manifold versus Gromov-Hausdorff, uniform, and intrinsic flat convergence of the corresponding sequence of metric spaces. We provide a number of examples which ... More
Various Covering Spectra for Complete Metric SpacesNov 30 2012Apr 29 2014We study various covering spectra for complete noncompact length spaces with universal covers (including Riemannian manifolds and the pointed Gromov Hausdorff limits of Riemannian manifolds with lower bounds on their Ricci curvature). We relate the covering ... More
Monoidal Grothendieck ConstructionSep 03 2018Feb 18 2019We lift the standard equivalence between fibrations and indexed categories to an equivalence between monoidal fibrations and monoidal indexed categories, namely weak monoidal pseudofunctors to the 2-category of categories. In doing so, we investigate ... More
Dual random fragmentation and coagulation and an application to the genealogy of Yule processesAug 10 2004The purpose of this work is to describe a duality between a fragmentation associated to certain Dirichlet distributions and a natural random coagulation. The dual fragmentation and coalescent chains arising in this setting appear in the description of ... More
A Polynomial-Time Algorithm for Pliable Index CodingOct 21 2016In pliable index coding, we consider a server with $m$ messages and $n$ clients where each client has as side information a subset of the messages. We seek to minimize the number of broadcast transmissions, so that each client can recover any one unknown ... More
Content-type codingMay 13 2015Jun 03 2015This paper is motivated by the observation that, in many cases, we do not need to serve specific messages, but rather, any message within a content-type. Content-type traffic pervades a host of applications today, ranging from search engines and recommender ... More
Determining both the source of a wave and its speed in a medium from boundary measurementsMar 18 2018May 29 2018We study the inverse problem of determining both the source of a wave and its speed inside a medium from measurements of the solution of the wave equation on the boundary. This problem arises in photoacoustic and thermoacoustic tomography, and has important ... More
The Architectural Implications of Microservices in the CloudMay 25 2018Cloud services have recently undergone a shift from monolithic applications to microservices, with hundreds or thousands of loosely-coupled microservices comprising the end-to-end application. Microservices present both opportunities and challenges when ... More
Fairness Under CompositionJun 15 2018Nov 20 2018Algorithmic fairness, and in particular the fairness of scoring and classification algorithms, has become a topic of increasing social concern and has recently witnessed an explosion of research in theoretical computer science, machine learning, statistics, ... More
A first step toward higher order chain rules in abelian functor calculusJul 15 2017One of the fundamental tools of undergraduate calculus is the chain rule. The notion of higher order directional derivatives was developed by Huang, Marcantognini, and Young, along with a corresponding higher order chain rule. When Johnson and McCarthy ... More
Intrinsic Flat Convergence of Covering SpacesSep 24 2014We examine the limits of covering spaces and the covering spectra of oriented Riemannian manifolds, $M_j$, which converge to a nonzero integral current space, $M_\infty$, in the intrinsic flat sense. We provide examples demonstrating that the covering ... More
Enumerating Acyclic Digraphs by DescentsSep 02 2017A descent of a labeled acyclic digraph is a directed edge $x\to y$ with $x>y$. In this paper, we find a recurrence for the number of labeled acyclic digraphs with a given number of descents.
The Topology of Open Manifolds with Nonnegative Ricci CurvatureJun 30 2006Nov 16 2006We survey all results concerning the topology of complete noncompact Riemannian manifolds with nonnegative Ricci curvature that have no additional conditions other than restrictions to the dimension, volume growth or diameter growth of the manifold. We ... More
Does indirectness of signal production reduce the explosion-supporting potential in chemotaxis-haptotaxis systems? Global classical solvability in a class of models for cancer invasion (and more)Apr 25 2019We propose and study a class of parabolic-ODE models involving chemotaxis and haptotaxis of a species following signals indirectly produced by another, non-motile one. The setting is motivated by cancer invasion mediated by interactions with the tumor ... More
The scaling limit of a critical random directed graphMay 14 2019We consider the random directed graph $\vec{G}(n,p)$ with vertex set $\{1,2,\ldots,n\}$ in which each of the $n(n-1)$ possible directed edges is present independently with probability $p$. We are interested in the strongly connected components of this ... More
The Cut-off Covering SpectrumMay 25 2007Sep 17 2008We introduce the $R$ cut-off covering spectrum and the cut-off covering spectrum of a complete length space or Riemannian manifold. The spectra measure the sizes of localized holes in the space and are defined using covering spaces called $\delta$ covers ... More
Essential edges in Poisson random hypergraphsJan 14 2004Apr 01 2004Consider a random hypergraph on a set of N vertices in which, for k between 1 and N, a Poisson(N beta_k) number of hyperedges is scattered randomly over all subsets of size k. We collapse the hypergraph by running the following algorithm to exhaustion: ... More
Resonance production from jet fragmentationJul 17 2009Short lived resonances are sensitive to the medium properties in heavy-ion collisions. Heavy hadrons have larger probability to be produced within the quark gluon plasma phase due to their short formation times. Therefore heavy mass resonances are more ... More
Hausdorff Convergence and Universal CoversAug 29 2000We prove that if $Y$ is the Gromov-Hausdorff limit of a sequence of compact manifolds, $M^n_i$, with a uniform lower bound on Ricci curvature and a uniform upper bound on diameter, then $Y$ has a universal cover. We then show that, for $i$ sufficiently ... More
The codimension one homology of a complete manifold with nonnegative Ricci curvatureSep 02 1999Nov 18 2000In this paper we prove that a complete noncompact manifold with nonnegative Ricci curvature has a trivial codimension one homology unless it is a split or flat normal bundle over a compact totally geodesic submanifold. In particular, we prove the conjecture ... More
A quantum causal discovery algorithmApr 03 2017Apr 19 2018Finding a causal model for a set of classical variables is now a well-established task---but what about the quantum equivalent? Even the notion of a quantum causal model is controversial. Here, we present a causal discovery algorithm for quantum systems. ... More
Nontrivial Periodic Solutions of Marine Ecosystem Models of N-DOP typeSep 26 2014We investigate marine ecosystem models of N-DOP type with regard to nontrivial periodic solutions. The elements of this important, widely-used model class typically consist of two coupled advection-diffusion-reaction equations. The corresponding reaction ... More
A line-breaking construction of the stable treesJul 21 2014We give a new, simple construction of the $\alpha$-stable tree for $\alpha \in (1,2]$. We obtain it as the closure of an increasing sequence of $\mathbb{R}$-trees inductively built by gluing together line-segments one by one. The lengths of these line-segments ... More
The spread of fire on a random multigraphOct 26 2017We study a model for the destruction of a random network by fire. Suppose that we are given a multigraph of minimum degree at least 2 having real-valued edge-lengths. We pick a uniform point from along the length and set it alight; the edges of the multigraph ... More
Conditional Variance Penalties and Domain Shift RobustnessOct 31 2017May 08 2018When training a deep network for image classification, one can broadly distinguish between two types of latent features of images that will drive the classification. Following the notation of Gong et al. (2016), we can divide latent features into (i) ... More
The Uncountability of the Unit IntervalSep 23 2012Jan 22 2014For any particularly interesting theorem one proof is never enough. Instead, the first proof sets the challenge to find a more elegant method that illuminates subtle features of the math, is simpler to understand, or even avoids using controversial subjects. ... More
The local $h$-vector of the cluster subdivision of a simplexApr 02 2012The cluster complex $\Delta (\Phi)$ is an abstract simplicial complex, introduced by Fomin and Zelevinsky for a finite root system $\Phi$. The positive part of $\Delta (\Phi)$ naturally defines a simplicial subdivision of the simplex on the vertex set ... More
A symmetric unimodal decomposition of the derangement polynomial of type $B$Mar 10 2013Mar 15 2013The derangement polynomial $d_n (x)$ for the symmetric group enumerates derangements by the number of excedances. The derangement polynomial $d^B_n(x)$ for the hyperoctahedral group is a natural type $B$ analogue. A new combinatorial formula for this ... More
Near-equality of the Penrose Inequality for rotationally symmetric Riemannian manifoldsSep 09 2011This article is the sequel to our previous paper [LS] dealing with the near-equality case of the Positive Mass Theorem. We study the near-equality case of the Penrose Inequality for the class of complete asymptotically flat rotationally symmetric Riemannian ... More
Opacity, Obscurity, and the Geometry of Question-AskingSep 21 2018Asking questions is a pervasive human activity, but little is understood about what makes them difficult to answer. An analysis of a pair of large databases, of New York Times crosswords and questions from the quiz-show Jeopardy, establishes two orthogonal ... More
Stability of the Positive Mass Theorem for Rotationally Symmetric Riemannian ManifoldsApr 14 2011May 04 2014We study the stability of the Positive Mass Theorem using the Intrinsic Flat Distance. In particular we consider the class of complete asymptotically flat rotationally symmetric Riemannian manifolds with nonnegative scalar curvature and no interior closed ... More
Reducing Crowdsourcing to Graphon Estimation, StatisticallyMar 23 2017Feb 21 2018Inferring the correct answers to binary tasks based on multiple noisy answers in an unsupervised manner has emerged as the canonical question for micro-task crowdsourcing or more generally aggregating opinions. In graphon estimation, one is interested ... More
Tree lengths for general $Λ$-coalescents and the asymptotic site frequency spectrum around the Bolthausen-Sznitman coalescentApr 03 2018Jan 22 2019We study tree lengths in $\Lambda$-coalescents without a dust component from a sample of $n$ individuals. For the total length of all branches and the total length of all external branches we present laws of large numbers in full generality. The other ... More
Crystallization and arrest mechanisms of model colloidsJul 24 2015We performed dynamic simulations of spheres with short-range attractive interactions for many values of interaction strength and range. Fast crystallization occurs in a localized region of this parameter space, but the character of crystallization pathways ... More
Compositionality and String Diagrams for Game TheoryApr 20 2016We introduce string diagrams as a formal mathematical, graphical language to represent, compose, program and reason about games. The language is well established in quantum physics, quantum computing and quantum linguistic with the semantics given by ... More
Fast Simulation of Facilitated Spin ModelsOct 13 2005Dec 21 2005We show how to apply the absorbing Markov chain Monte Carlo algorithm of Novotny to simulate kinetically constrained models of glasses. We consider in detail one-spin facilitated models, such as the East model and its generalizations to arbitrary dimensions. ... More
The selection monad as a CPS transformationMar 20 2015A computation in the continuation monad returns a final result given a continuation, ie. it is a function with type $(X \to R) \to R$. If we instead return the intermediate result at $X$ then our computation is called a selection function. Selection functions ... More
A Market for Unbiased Private Data: Paying Individuals According to their Privacy AttitudesApr 30 2012Since there is, in principle, no reason why third parties should not pay individuals for the use of their data, we introduce a realistic market that would allow these payments to be made while taking into account the privacy attitude of the participants. ... More
Social Attention and the Provider's DilemmaSep 27 2010While attracting attention is one of the prime goals of content providers, the conversion of that attention into revenue is by no means obvious. Given that most users expect to consume web content for free, a provider with an established audience faces ... More
(Metric) Bisimulation Games and Real-Valued Modal Logics for CoalgebrasMay 29 2017Jul 03 2018Behavioural equivalences can be characterized via bisimulations, modal logics and spoiler-defender games. In this paper we review these three perspectives in a coalgebraic setting, which allows us to generalize from the particular branching type of a ... More
Robust Optimization under Multi-band Uncertainty - Part I: TheoryJan 12 2013Mar 14 2013The classical single-band uncertainty model introduced by Bertsimas and Sim has represented a breakthrough in the development of tractable robust counterparts of Linear Programs. However, adopting a single deviation band may be too limitative in practice: ... More
Random recursive trees and the Bolthausen-Sznitman coalescentFeb 13 2005Jun 02 2005We describe a representation of the Bolthausen-Sznitman coalescent in terms of the cutting of random recursive trees. Using this representation, we prove results concerning the final collision of the coalescent restricted to [n]: we show that the distribution ... More
External branch lengths of $Λ$-coalescents without a dust componentNov 19 2018$\Lambda$-coalescents model genealogies of samples of individuals from a large population, and the individuals' time durations up to some common ancestor are given by the external branch lengths of the family tree. We consider typical external branches ... More
Triangle Decompositions of Planar GraphsApr 02 2015A multigraph G is triangle decomposable if its edge set can be partitioned into subsets, each of which induces a triangle of G, and rationally triangle decomposable if its triangles can be assigned rational weights such that for each edge e of G, the ... More
Asymptotics of the allele frequency spectrum associated with the Bolthausen-Sznitman coalescentJun 19 2007We work in the context of the infinitely many alleles model. The allelic partition associated with a coalescent process started from n individuals is obtained by placing mutations along the skeleton of the coalescent tree; for each individual, we trace ... More
New results about multi-band uncertainty in Robust OptimizationAug 30 2012"The Price of Robustness" by Bertsimas and Sim represented a breakthrough in the development of a tractable robust counterpart of Linear Programming Problems. However, the central modeling assumption that the deviation band of each uncertain parameter ... More
Self-assembly at a nonequilibrium critical pointOct 29 2013Apr 03 2014We use analytic theory and computer simulation to study patterns formed during the growth of two-component assemblies in 2D and 3D. We show that these patterns undergo a nonequilibrium phase transition, at a particular growth rate, between mixed and demixed ... More
De-coupling of Exchange and Persistence Times in Atomistic Models of Glass FormersAug 06 2007Dec 07 2007With molecular dynamics simulations of a fluid mixture of classical particles interacting with pair-wise additive Weeks-Chandler-Andersen potentials, we consider the time series of particle displacements and thereby determine distributions for local persistence ... More
A Higher-order Framework for Decision Problems and GamesSep 25 2014We introduce a new unified framework for modelling both decision problems and finite games based on quantifiers and selection functions. We show that the canonical utility maximisation is one special case of a quantifier and that our more abstract framework ... More
Higher-Order Decision TheoryJun 02 2015Jun 03 2015Classical decision theory models behaviour in terms of utility maximisation where utilities represent rational preference relations over outcomes. However, empirical evidence and theoretical considerations suggest that we need to go beyond this framework. ... More
Regret vs. Bandwidth Trade-off for Recommendation SystemsOct 15 2018We consider recommendation systems that need to operate under wireless bandwidth constraints, measured as number of broadcast transmissions, and demonstrate a (tight for some instances) tradeoff between regret and bandwidth for two scenarios: the case ... More