Results for "David Cushing"

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Free functions with symmetrySep 05 2014In 1936, Margarete C. Wolf showed that the ring of symmetric free polynomials in two or more variables is isomorphic to the ring of free polynomials in infinitely many variables. We show that Wolf's theorem is a special case of a general theory of the ... More
Projectivity of Banach and $C^*$-algebras of continuous fieldsApr 26 2011We give necessary and sufficient conditions for the left projectivity and biprojectivity of Banach algebras defined by locally trivial continuous fields of Banach algebras. We identify projective $C^*$-algebras $\A$ defined by locally trivial continuous ... More
Powerful numbers and the ABC-conjectureNov 03 2016The $abc$ conjecture is a very deep concept in number theory with wide application to many areas of number theory. In this article we introduce the conjecture and give examples of its applications. In particular we apply the $abc$ conjecture to the location ... More
The additive structure of the squares inside ringsNov 04 2016When defining the amount of additive structure on a set it is often convenient to consider certain sumsets; Calculating the cardinality of these sumsets can elucidate the set's underlying structure. We begin by investigating finite sets of perfect squares ... More
Bakry-Émery curvature functions of graphsJun 05 2016Aug 15 2017We study the Bakry-\'Emery curvature function $\mathcal{K}_{G,x}:(0,\infty]\to \mathbb{R}$ of a vertex $x$ in a locally finite graph $G$ systematically. Here $\mathcal{K}_{G,x}(\mathcal{N})$ is defined as the optimal curvature lower bound $\mathcal{K}$ ... More
Bakry-Émery curvature functions of graphsJun 05 2016We study the Bakry-\'Emery curvature function $\mathcal{K}_{G,x}:(0,\infty]\to \mathbb{R}$ of a vertex $x$ in a locally finite graph $G$ systematically. Here $\mathcal{K}_{G,x}(\mathcal{N})$ is defined as the optimal curvature lower bound $\mathcal{K}$ ... More
Ollivier-Ricci idleness functions of graphsApr 14 2017Jul 04 2017We study the Ollivier-Ricci curvature of graphs as a function of the chosen idleness. We show that this idleness function is concave and piecewise linear with at most $3$ linear parts, with at most $2$ linear parts in the case of a regular graph. We then ... More
Quartic graphs which are Bakry-Émery curvature sharpFeb 27 2019We give a classification of all connected quartic graphs which are (infinity) curvature sharp in all vertices with respect to Bakry-\'Emery curvature. The result is based on a computer classification by F. Gurr and L. Watson May and a combinatorial case ... More
Curvature calculations for antitreesJan 29 2018In this article we prove that antitrees with suitable growth properties are examples of infinite graphs exhibiting strictly positive curvature in various contexts: in the normalized and non-normalized Bakry-\'Emery setting as well in the Ollivier-Ricci ... More
Rigidity of the Bonnet-Myers inequality for graphs with respect to Ollivier Ricci curvatureJul 06 2018We introduce the notion of Bonnet-Myers and Lichnerowicz sharpness in the Ollivier Ricci curvature sense. Our main result is a classification of all self-centered Bonnet-Myers sharp graphs (hypercubes, cocktail party graphs, even-dimensional demi-cubes, ... More
Erratum for Ricci-flat graphs with girth at least fiveFeb 08 2018May 08 2019This erratum will correct the classification of Theorem 1 in Lin-Lu-Yau, Comm. Anal. Geom., 2014, that misses the Triplex graph.
Erratum for Ricci-flat graphs with girth at least fiveFeb 08 2018This erratum will correct the classification of Theorem 1 in Lin-Lu-Yau, Comm. Anal. Geom., 2014, that misses the Triplex graph.
Ricci-flat cubic graphs with girth fiveFeb 08 2018We classify all connected, simple, 3-regular graphs with girth at least 5 that are Ricci-flat. We use the definition of Ricci curvature on graphs given in Lin-Lu-Yau, Tohoku Math., 2011, which is a variation of Ollivier, J. Funct. Anal., 2009. A graph ... More
Kepler Planet Occurrence Rates for Mid-Type M Dwarfs as a Function of Spectral TypeMay 15 2019Previous studies of planet occurrence rates largely relied on photometric stellar characterizations. In this paper, we present planet occurrence rates for mid-type M dwarfs using spectroscopy, parallaxes, and photometry to determine stellar characteristics. ... More
The 0.8-14.5 micron Spectra of Mid-L to Mid-T Dwarfs: Diagnostics of Effective Temperature, Grain Sedimentation, Gas Transport, and Surface GravityJun 16 2009We present new 5.2-14.5 micron low-resolution spectra of 14 mid-L to mid-T dwarfs, as well as 3.0-4.1 micron spectra for five of these dwarfs. These data are supplemented by existing red and near-infrared spectra (0.6-2.5 micron), as well as red through ... More
Near-infrared Thermal Emission Detections of a number of hot Jupiters and the Systematics of Ground-based Near-infrared PhotometryOct 16 2014We present detections of the near-infrared thermal emission of three hot Jupiters and one brown-dwarf using the Wide-field Infrared Camera (WIRCam) on the Canada-France-Hawaii Telescope (CFHT). These include Ks-band secondary eclipse detections of the ... More
Science Impacts of the SPHEREx All-Sky Optical to Near-Infrared Spectral Survey II: Report of a Community Workshop on the Scientific Synergies Between the SPHEREx Survey and Other Astronomy ObservatoriesMay 14 2018May 24 2018SPHEREx is a proposed NASA MIDEX mission selected for Phase A study. SPHEREx would carry out the first all-sky spectral survey in the near infrared. At the end of its two-year mission, SPHEREx would obtain 0.75-to-5$\mu$m spectra of every 6.2 arcsec pixel ... More
The Schizophrenic Spectrum of LSR 1610-0040: a Peculiar M Dwarf/SubdwarfNov 14 2005We present a moderate resolution (R=2000), 0.8-4.1 micron spectrum of LSR 1610-0040, a high proper motion star classified as an early-type L subdwarf by Lepine and collaborators based on its red-optical spectrum. The near-infrared spectrum of LSR 1610-0040 ... More
Direct and Simultaneous Observation of Ultrafast Electron and Hole Dynamics in GermaniumFeb 10 2017Understanding excited carrier dynamics in semiconductors is crucial for the development of photovoltaics and efficient photonic devices. However, overlapping spectral features in optical/NIR pump-probe spectroscopy often render assignments of separate ... More
Science Impacts of the SPHEREx All-Sky Optical to Near-Infrared Spectral Survey: Report of a Community Workshop Examining Extragalactic, Galactic, Stellar and Planetary ScienceJun 22 2016SPHEREx is a proposed SMEX mission selected for Phase A. SPHEREx will carry out the first all-sky spectral survey and provide for every 6.2" pixel a spectra between 0.75 and 4.18 $\mu$m [with R$\sim$41.4] and 4.18 and 5.00 $\mu$m [with R$\sim$135]. The ... More
A Candidate Dual AGN at z=1.175Sep 15 2011The X-ray source CXOXBJ142607.6+353351 (CXOJ1426+35), which was identified in a 172 ks Chandra image in the Bootes field, shows double-peaked rest-frame optical/UV emission lines, separated by 0.69" (5.5 kpc) in the spatial dimension and by 690 km s^-1 ... More
Results from the Wide-field Infrared Survey Explorer (WISE) Future Uses Session at the WISE at 5 MeetingMay 08 2015During the "WISE at 5: Legacy and Prospects" conference in Pasadena, CA -- which ran from February 10 - 12, 2015 -- attendees were invited to engage in an interactive session exploring the future uses of the Wide-field Infrared Survey Explorer (WISE) ... More
An Infrared High Proper Motion Survey Using 2MASS and SDSS: Discovery of M, L and T DwarfsSep 03 2008Oct 17 2008A search of the Two Micron All Sky Survey and Sloan Digital Sky Survey reveals 36 previously unknown high proper motion objects with J<17. Their red-optical colors indicate that 27 are M dwarfs, 8 are early-type L dwarfs, and 1 is a late-type T dwarf. ... More
Cost Based Satisficing Search Considered HarmfulMar 18 2011Recently, several researchers have found that cost-based satisficing search with A* often runs into problems. Although some "work arounds" have been proposed to ameliorate the problem, there has not been any concerted effort to pinpoint its origin. In ... More
The L to T Dwarf TransitionSep 10 2004While the precise mechanism responsible for the L to T dwarf transition remains unclear, it is clearly caused by changing cloud characteristics. Here we briefly review data relevant to understanding the nature of the transition and argue that changing ... More
Non-Linearity Corrections and Statistical Uncertainties Associated with Near-Infrared ArraysJan 20 2004We derive general equations for non-linearity corrections and statistical uncertainty (variance) estimates for data acquired with near-infrared detectors employing correlated double sampling, multiple correlated double sampling (Fowler sampling) and uniformly-spaced ... More
Radii of 88 M Subdwarfs and Updated Radius Relations for Low-Metallicity M Dwarf StarsOct 17 2018M subdwarfs are low-metallicity M dwarfs that typically inhabit the halo population of the Galaxy. Metallicity controls the opacity of stellar atmospheres; in metal poor stars, hydrostatic equilibrium is reached at a smaller radius, leading to smaller ... More
Surrogate Search As a Way to Combat Harmful Effects of Ill-behaved Evaluation FunctionsNov 01 2014Recently, several researchers have found that cost-based satisficing search with A* often runs into problems. Although some "work arounds" have been proposed to ameliorate the problem, there has been little concerted effort to pinpoint its origin. In ... More
The Benchmark Ultracool Subdwarf HD 114762B: A Test of Low-Metallicity Atmospheric and Evolutionary ModelsOct 08 2009We present a near-infrared spectroscopic study of HD 114762B, the latest-type metal-poor companion discovered to date and the only ultracool subdwarf with a known metallicity, inferred from the primary star to be [Fe/H] = -0.7. We obtained a medium-resolution ... More
The Infrared Telescope Facility (IRTF) Spectral Library: Cool StarsSep 04 2009We present a 0.8 -5 micron spectral library of 210 cool stars observed at a resolving power of R = lambda / Delta lambda ~ 2000 with the medium-resolution infrared spectrograph, SpeX, at the 3.0 m NASA Infrared Telescope Facility (IRTF) on Mauna Kea, ... More
A Method of Correcting Near-Infrared Spectra for Telluric AbsorptionNov 12 2002We present a method for correcting near-infrared medium-resolution spectra for telluric absorption. The method makes use of a spectrum of an A0V star, observed near in time and close in airmass to the target object, and a high-resolution model of Vega, ... More
SDSS J141624.08+134826.7: Blue L Dwarfs and Non-Equilibrium ChemistrySep 14 2010We present an analysis of the recently discovered blue L dwarf SDSS J141624.08+134826.7. We extend the spectral coverage of its published spectrum to ~4 microns by obtaining a low-resolution L band spectrum with SpeX on the NASA IRTF. The spectrum exhibits ... More
An Infrared Spectroscopic Sequence of M, L and T DwarfsDec 13 2004We present a 0.6-4.1 micron spectroscopic sequence of M, L, and T dwarfs. The spectra have R~2000 from 0.9 to 2.4 microns and R=2500-200 from 2.9 to 4.1 microns. These new data nearly double the number of L and T dwarfs that have reported L-band spectra. ... More
Near-Infrared Spectroscopy of McNeil's Nebula ObjectMay 24 2004We present 0.8-5.2 micron spectroscopy of the compact source at the base of a variable nebula (McNeil's Nebula Object) in the Lynds 1630 dark cloud that went into outburst in late 2003. The spectrum of this object reveals an extremely red continuum, CO ... More
Learning Probabilistic Hierarchical Task Networks to Capture User PreferencesJun 02 2010We propose automatically learning probabilistic Hierarchical Task Networks (pHTNs) in order to capture a user's preferences on plans, by observing only the user's behavior. HTNs are a common choice of representation for a variety of purposes in planning, ... More
The transverse proximity effect in the z ~ 2 Lyman-alpha forest suggests QSO episodic lifetimes of ~1 MyrSep 12 2008We look for signs of the H~I transverse proximity effect in the spectra of 130 QSO pairs, most with transverse separations in the plane of the sky of 0.1 -- 3 Mpc at z ~ 2.2. We expected to see a decrease in Lyman-alpha forest HI absorption in the spectrum ... More
Comet Encounters and Carbon 14Nov 26 2012The $^{14}$C production of shock-accelerated particles is calculated in terms of the total energy released in energetic particles. The recently reported 1.2% jump in the $^{14}$C content of the atmosphere in the year C.E. 775, it is found, would require ... More
The Detection of Two Distinct High Ionization States in a QSO Lyman Limit Absorption System: Evidence for Hierarchical Galaxy Formation at z ~ 3?Jan 19 1999We have detected two high ionization phases of gas in the z ~ 2.77 partial Lyman limit system (LLS) towards QSO 1157-3143. We detect the first phase by CIV and SiIV absorption, and the second phase -- which is either warmer or undergoing larger random ... More
Stable Leader Election in Population Protocols Requires Linear TimeFeb 14 2015Aug 20 2016A population protocol *stably elects a leader* if, for all $n$, starting from an initial configuration with $n$ agents each in an identical state, with probability 1 it reaches a configuration $\mathbf{y}$ that is correct (exactly one agent is in a special ... More
Integrals derived from the doubling methodOct 21 2018In this note, we use a basic identity, derived from the generalized doubling integrals of \cite{C-F-G-K1}, in order to explain the existence of various global Rankin-Selberg integrals for certain $L$-functions. To derive these global integrals, we use ... More
Continuum Percolation for Quermass ModelJan 11 2012The continuum percolation for Markov (or Gibbs) germ-grain models is investigated. The grains are assumed circular with random radii on a compact support. The morphological interaction is the so-called Quermass interaction defined by a linear combination ... More
Randomized greedy algorithms for independent sets and matchings in regular graphs: Exact results and finite girth correctionsJul 08 2008We derive new results for the performance of a simple greedy algorithm for finding large independent sets and matchings in constant degree regular graphs. We show that for $r$-regular graphs with $n$ nodes and girth at least $g$, the algorithm finds an ... More
Two Identities relating Eisenstein series on classical groupsAug 05 2018In this paper we introduce two general identities relating Eisenstein series on split classical groups, as well as double covers of symplectic groups. The first identity can be viewed as an extension of the doubling construction introduced in [CFGK17]. ... More
The RASNIK Real-Time Relative Alignment Monitor for the CDF Inner Tracking DetectorsDec 10 2002We describe the design and operation of the RASNIK optical relative alignment system designed for and installed on the CDF inner tracking detectors. The system provides low-cost minute-by-minute alignment monitoring with submicron precision. To reduce ... More
Results for the LISA Phase Measurement System ProjectNov 01 2004Jan 11 2005This article presents some of the more topical results of a study into the LISA phase measurement system. This system is responsible for measuring the phase of the heterodyne signal caused by the interference of the laser beams between the local and far ... More
Site Disordered Spin Systems in the Gaussian Variational ApproximationJun 06 1996Dec 16 1996We define a replica field theory describing finite dimensional site disordered spin systems by introducing the notion of grand canonical disorder, where the number of spins in the system is random but quenched. A general analysis of this field theory ... More
Splitting cycles in graphsApr 26 2012The goal of this paper is to describe a sufficient condition on cycles in graphs for which the edge ideal is splittable. We give an explicit splitting function for such ideals.
Studying the Physical Diversity of Late-M Dwarfs with Dynamical MassesJul 23 2010We present a systematic study of the physical properties of late-M dwarfs based on high-quality dynamical mass measurements and near-infrared (NIR) spectra. We use astrometry from Keck NGS and LGS AO imaging to determine orbits for late-M binaries. We ... More
Photometric Monitoring of the Coldest Known Brown Dwarf with the Spitzer Space TelescopeSep 19 2016Sep 20 2016Because WISE J085510.83$-$071442.5 (hereafter WISE 0855-0714) is the coldest known brown dwarf ($\sim250$ K) and one of the Sun's closest neighbors (2.2 pc), it offers a unique opportunity for studying a planet-like atmosphere in an unexplored regime ... More
Hilbert function spaces and the Nevanlinna-Pick problem on the polydisc IIFeb 21 2013In \cite{ds_hfs}, a geometric procedure for constructing a Nevanlinna-Pick problem on $\D^n$ with a specified set of uniqueness was established. In this sequel we conjecture a necessary and a sufficient condition for a Nevanlinna-Pick problem on $\DT$ ... More
Wrapped microlocal sheaves on pairs of pantsApr 01 2016Inspired by the geometry of wrapped Fukaya categories, we introduce the notion of wrapped microlocal sheaves. We show that traditional microlocal sheaves are equivalent to functionals on wrapped microlocal sheaves, in analogy with the expected relation ... More
Higher Lie and Leibniz algebrasJan 08 2015Jan 10 2015Higher structures - infinity algebras and other objects up to homotopy, categorified algebras, `oidified' concepts, operads, higher categories, higher Lie theory, higher gauge theory... - are currently intensively investigated in Mathematics and Physics. ... More
The Cantor-Bendixson Rank of Certain Bridgeland-Smith Stability ConditionsDec 08 2015Jun 08 2016We provide a novel proof that the set of directions that admit a saddle connection on a meromorphic quadratic differential with at least one pole of order at least two is closed, which generalizes a result of Bridgeland and Smith, and Gaiotto, Moore, ... More
On Double-Entry Bookkeeping: The Mathematical TreatmentJul 07 2014Double-entry bookkeeping (DEB) implicitly uses a specific mathematical construction, the group of differences using pairs of unsigned numbers ("T-accounts"). That construction was only formulated abstractly in mathematics in the 19th century--even though ... More
Niépce-Bell or Turing: How to Test Odor Reproduction?Mar 29 2016Apr 28 2016In 1950 Alan Turing proposed his imitation game, better known as the Turing test, for determining whether a computer system claimed to adequately exhibit intelligence indeed does so. This work was carried out although no such system was anywhere in sight ... More
The probability of generating the symmetric group with a commutator conditionMay 30 2012Dec 08 2013Let B(n) be the set of pairs of permutations from the symmetric group of degree n with a 3-cycle commutator, and let A(n) be the set of those pairs which generate the symmetric or the alternating group of degree n. We find effective formulas for calculating ... More
A topological approach to induction theorems in Springer theorySep 16 2008We give a self-contained account of a construction due to Rossmann which lifts Springer's action of a Weyl group on the cohomology of a Springer fiber to an action on its homotopy type. We use this construction to produce a generalization of an "induction ... More
Accelerating Branes and the String/Black Hole TransitionSep 22 2005String theory in Euclidean flat space with a spacelike linear dilaton contains a D1-brane which looks like a semi-infinite hairpin. In addition to its curved shape, this ``hairpin brane'' has a condensate of the open string tachyon stretched between its ... More
Usability Meets Instant Gratification on the Semantic WebNov 10 2010This paper presents a semantic wiki prototype application named SHAWN [later WikSAR] that allows structuring concepts within a wiki environment. To entice the use of Semantic Web technologies applications need to offer both high usability and instant ... More
A combinatorial interpretation of the eigensequence for compositionJul 08 2005Jul 20 2005The monic sequence that shifts left under convolution with itself is the Catalan numbers with 130+ combinatorial interpretations. Here we establish a combinatorial interpretation for the monic sequence that shifts left under composition: it counts permutations ... More
Some bijections for restricted Motzkin pathsJul 22 2004We give several bijections among restricted Motzkin paths, explaining why various parameters on these paths are equidistributed. For example, the number of doublerise-free Motzkin paths of length n is the same as the number of peak-free Motzkin paths ... More
Pattern avoidance in circular permutationsOct 01 2002Circular permutations on {1,2,...,n} that avoid a given pattern correspond to ordinary (linear) permutations that end with n and avoid all cyclic rotations of the pattern. Three letter patterns are all but unavoidable in circular permutations and here ... More
A uniformly distributed parameter on a class of lattice pathsOct 29 2003Let G_n denote the set of lattice paths from (0,0) to (n,n) with steps of the form (i,j) where i and j are nonnegative integers, not both 0. Let D_n denote the set of paths in G_n with steps restricted to (1,0), (0,1), (1,1), so-called Delannoy paths. ... More
Similarity of the Temperature Profile formed by Fluid Flow along a WallMar 15 2016A new approach to the study of similarity of temperature profiles is presented. It is applicable for any 2-D fluid flow along an isothermal heated (cooled) wall. The approach is based on a simple concept; the area under a set of scaled temperature profile ... More
Determination through Universals: An Application of Category Theory in the Life SciencesMay 29 2013Category theory has foundational importance because it provides conceptual lenses to characterize what is important and universal in mathematics---with adjunctions being the primary lense. If adjunctions are so important in mathematics, then perhaps they ... More
On the information-theoretic structure of distributed measurementsJul 06 2011Jul 31 2012The internal structure of a measuring device, which depends on what its components are and how they are organized, determines how it categorizes its inputs. This paper presents a geometric approach to studying the internal structure of measurements performed ... More
Detecting emergent processes in cellular automata with excess informationMay 01 2011Sep 22 2011Many natural processes occur over characteristic spatial and temporal scales. This paper presents tools for (i) flexibly and scalably coarse-graining cellular automata and (ii) identifying which coarse-grainings express an automaton's dynamics well, and ... More
Spooky Action at No Distance: On the individuation of quantum mechanical systemsMar 11 2016Recent experiments have perfectly verified the fact that quantum correlations between two entangled particles are stronger than any classical, local pre-quantum worldview allows. This is famously called the EPR paradox first conceived as a thought experiment ... More
The Logic of Experimental Tests, Particularly of Everettian Quantum TheoryAug 09 2015Jun 18 2016Claims that the standard methodology of scientific testing is inapplicable to Everettian quantum theory, and hence that the theory is untestable, are due to misconceptions about probability and about the logic of experimental testing. Refuting those claims ... More
Some cohomology of finite general linear groupsSep 13 2015We prove that the degree $r(2p-3)$ cohomology of any (untwisted) finite group of Lie type over $\mathbb{F}_{p^r}$, with coefficients in characteristic $p$, is nonzero as long as its Coxeter number is at most $p$. We do this by providing a simple explicit ... More
The K-theory of filtered deformations of graded polynomial algebrasNov 20 2013Recent discoveries make it possible to compute the K-theory of certain rings from their cyclic homology and certain versions of their cdh-cohomology. We extend the work of G. Corti\~nas et al. who calculated the K-theory of, in addition to many other ... More
Tagset Design and Inflected LanguagesApr 03 1995Apr 04 1995An experiment designed to explore the relationship between tagging accuracy and the nature of the tagset is described, using corpora in English, French and Swedish. In particular, the question of internal versus external criteria for tagset design is ... More
Does Baum-Welch Re-estimation Help Taggers?Oct 21 1994Oct 24 1994In part of speech tagging by Hidden Markov Model, a statistical model is used to assign grammatical categories to words in a text. Early work in the field relied on a corpus which had been tagged by a human annotator to train the model. More recently, ... More
Incremental Interpretation of Categorial GrammarMar 14 1995The paper describes a parser for Categorial Grammar which provides fully word by word incremental interpretation. The parser does not require fragments of sentences to form constituents, and thereby avoids problems of spurious ambiguity. The paper includes ... More
Superharmonicity of Logarithm of Jacobian of harmonic mappings between surfacesMar 21 2016We prove that the Logarithm of the Jacobian of a sense preserving harmonic mappings between surfaces is superharmonic, provided that the Gaussian curvature of the image domain is non-negative.
Muckenhoupt weights and Lindelöf theorem for harmonic mappingsOct 30 2014We extend the result of Lavrentiev which asserts that the harmonic measure and the arc-length measure are $A_\infty$ equivalent in a chord-arc Jordan domain. By using this result we extend the classical result of Lindel\"of to the class of quasiconformal ... More
Direct Analysis of Spectra of Type Ib SupernovaeJun 20 2001Synthetic spectra generated with the parameterized supernova synthetic-spectrum code SYNOW are compared to photospheric-phase spectra of Type Ib supernovae (SNe Ib). Although the synthetic spectra are based on many simplifying approximations, including ... More
Type Ia Supernovae: Toward the Standard Model?Dec 13 2000In this short review I suggest that recent developments support the conjecture that Type Ia supernovae (SNe Ia) are the complete disruptions of Chandrasekhar-mass carbon-oxygen white dwarfs in single-degenerate binary systems. The causes of the observational ... More
Solar and Extrasolar Planet TaxonomyAug 02 2013Oct 11 2014A mass-based definition for planets is proposed with dynamical circumstances and compositional characteristics used to define types of planets. Dynamical planet classes include Principal planets, Belt planets, Moons, and Rogue planets. Compositional classes ... More
Cosmological Questions for the European Southern Observatory Very Large TelescopeAug 12 1996The next decade promises an observational revolution which will change cosmology forever. The precise measurement of the angular anisotropy of the cosmic microwave background should specify to a few percent all of the parameters of the cosmological model ... More
Stabilizing and destabilizing Heegaard splittings of sufficiently complicated 3-manifoldsJan 17 2012Let M_1 and M_2 be compact, orientable 3-manifolds with incompressible boundary, and M the manifold obtained by gluing with a homeomorphism $\phi:\bdy M_1 \to \bdy M_2$. We analyze the relationship between the sets of low genus Heegaard splittings of ... More
Regular Labelings and Geometric StructuresJul 01 2010Three types of geometric structure---grid triangulations, rectangular subdivisions, and orthogonal polyhedra---can each be described combinatorially by a regular labeling: an assignment of colors and orientations to the edges of an associated maximal ... More
Optimally fast incremental Manhattan plane embedding and planar tight span constructionSep 10 2009Oct 28 2011We describe a data structure, a rectangular complex, that can be used to represent hyperconvex metric spaces that have the same topology (although not necessarily the same distance function) as subsets of the plane. We show how to use this data structure ... More
Upright-Quad Drawing of st-Planar Learning SpacesJul 20 2006We consider graph drawing algorithms for learning spaces, a type of st-oriented partial cube derived from antimatroids and used to model states of knowledge of students. We show how to draw any st-planar learning space so all internal faces are convex ... More
The lattice dimension of a graphFeb 13 2004We describe a polynomial time algorithm for, given an undirected graph G, finding the minimum dimension d such that G may be isometrically embedded into the d-dimensional integer lattice Z^d.
Treetopes and their GraphsOct 12 2015We define treetopes, a generalization of the three-dimensional roofless polyhedra (Halin graphs) to arbitrary dimensions. Like roofless polyhedra, treetopes have a designated base facet such that every face of dimension greater than one intersects the ... More
Diamond-Kite Adaptive Quadrilateral MeshingJul 21 2012Jan 08 2013We describe a family of quadrilateral meshes based on diamonds, rhombi with 60 and 120 degree angles, and kites with 60, 90, and 120 degree angles, that can be adapted to a local size function by local subdivision operations. Our meshes use a number of ... More
Solving Single-digit Sudoku SubproblemsFeb 23 2012Mar 04 2012We show that single-digit "Nishio" subproblems in nxn Sudoku puzzles may be solved in time o(2^n), faster than previous solutions such as the pattern overlay method. We also show that single-digit deduction in Sudoku is NP-hard.
Isometric Diamond SubgraphsJul 14 2008We describe polynomial time algorithms for determining whether an undirected graph may be embedded in a distance-preserving way into the hexagonal tiling of the plane, the diamond structure in three dimensions, or analogous structures in higher dimensions. ... More
Finding Large Clique Minors is HardJun 30 2008May 13 2009We prove that it is NP-complete, given a graph G and a parameter h, to determine whether G contains a complete graph K_h as a minor.
Setting Parameters by ExampleJul 02 1999We introduce a class of "inverse parametric optimization" problems, in which one is given both a parametric optimization problem and a desired optimal solution; the task is to determine parameter values that lead to the given solution. We describe algorithms ... More
Zero-temperature criticality in a simple glass modelAug 04 1999We introduce the strongly-interacting trap model, a version of Bouchaud's trap model for glasses [Bouchaud J-P 1992 {\em J. Phys. I France {\bf 2}} 1705]. At finite temperatures the model exhibits glassy relaxation over intermediate timeframes but reaches ... More
A stability criterion for two-fluid interfaces and applicationsMay 25 2010We derive here a new stability criterion for two-fluid interfaces. This criterion ensures the existence of "stable" local solutions that do no break down too fast due to Kelvin-Helmholtz instabilities. It can be seen both as a two-fluid generalization ... More
Progressive Temporal Window WideningApr 04 2016Jul 03 2016This paper introduces a scheme for data stream processing which is robust to batch duration. Streaming frameworks process streams in batches retrieved at fixed time intervals. In a common setting a pattern recognition algorithm is applied independently ... More
On the connection between affine and projective fundamental groups of line arrangements and curvesDec 31 2002Feb 27 2003In this note we prove a decomposition related to the affine fundamental group and the projective fundamental group of a line arrangement and a reducible curve with a line component. We give some applications to this result.
High-pT pi0 Production with Respect to the Reaction Plane Using the PHENIX Detector at RHICSep 13 2006The origin of the azimuthal anisotropy in particle yields at high pT (pT > 5 GeV/c) in RHIC collisions remains an intriguing puzzle. Traditional flow and parton energy loss models have failed to completely explain the large v2 observed at high pT. Measurement ... More
High-pT Particle Production with Respect to the Reaction PlaneJul 10 2006The PHENIX Run4 data-set provides a powerful opportunity for exploring the angular anisotropy of identified particle yields at high pT. Complementing traditional v2 measurements, we present pi0 yields as a function of emission angle with respect to the ... More
PHENIX Results on Jet Correlations versus Reaction PlaneAug 04 2008In relativistic heavy-ion collisions, studying jet correlations and their dependence on the angle of emission with respect to the reaction plane can be used to shed light on the path length dependence of the energy lost by the jet. In this paper, we present ... More
Statistical Mechanics of systems with long range interactionsNov 19 2008Recent theoretical studies of statistical mechanical properties of systems with long range interactions are briefly reviewed. In these systems the interaction potential decays with a rate slower than 1/r^d at large distances r in d dimensions. As a result, ... More
A Review of the Current Status of Follow-Up Techniques to Study Known Extrasolar PlanetsDec 10 2003I present a review of observational efforts to study known extrasolar planets by methods that are complementary to the radial velocity technique. I describe the current state of attempts to detect and characterize such planets by astrometry, by reflected ... More