Results for "Michael Cerny Green"

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Organic Building Generation in MinecraftJun 11 2019This paper presents a method for generating floor plans for structures in Minecraft (Mojang 2009). Given a 3D space, it will auto-generate a building to fill that space using a combination of constrained growth and cellular automata. The result is a series ... More
Evolutionarily-Curated Curriculum Learning for Deep Reinforcement Learning AgentsJan 16 2019In this paper we propose a new training loop for deep reinforcement learning agents with an evolutionary generator. Evolutionary procedural content generation has been used in the creation of maps and levels for games before. Our system incorporates an ... More
General Video Game Rule GenerationJun 12 2019We introduce the General Video Game Rule Generation problem, and the eponymous software framework which will be used in a new track of the General Video Game AI (GVGAI) competition. The problem is, given a game level as input, to generate the rules of ... More
Generating Levels That Teach MechanicsJul 18 2018Oct 01 2018The automatic generation of game tutorials is a challenging AI problem. While it is possible to generate annotations and instructions that explain to the player how the game is played, this paper focuses on generating a gameplay experience that introduces ... More
Data-driven Design: A Case for Maximalist Game DesignMay 30 2018Maximalism in art refers to drawing on and combining multiple different sources for art creation, embracing the resulting collisions and heterogeneity. This paper discusses the use of maximalism in game design and particularly in data games, which are ... More
AtDelfi: Automatically Designing Legible, Full Instructions For GamesJul 11 2018Sep 17 2018This paper introduces a fully automatic method for generating video game tutorials. The AtDELFI system (AuTomatically DEsigning Legible, Full Instructions for games) was created to investigate procedural generation of instructions that teach players how ... More
Who Killed Albert Einstein? From Open Data to Murder Mystery GamesFeb 14 2018This paper presents a framework for generating adventure games from open data. Focusing on the murder mystery type of adventure games, the generator is able to transform open data from Wikipedia articles, OpenStreetMap and images from Wikimedia Commons ... More
Two-step Constructive Approaches for Dungeon GenerationJun 11 2019This paper presents a two-step generative approach for creating dungeons in the rogue-like puzzle game MiniDungeons 2. Generation is split into two steps, initially producing the architectural layout of the level as its walls and floor tiles, and then ... More
Boundary Effects in String TheoryOct 04 1995Some of the properties of string theory defined on world-sheets with boundaries are reviewed. Particular emphasis is put on the possibility of identifying string configurations (\lq D-instantons' and \lq D-branes') that give rise to stringy non-perturbative ... More
Temperature Dependence of String Theory in the Presence of World-Sheet BoundariesJan 27 1992Jan 29 1992The effect of world-sheet boundaries on the temperature-dependence of bosonic string theory is studied to first order in string perturbation theory. The high- temperature behaviour of a theory with Dirichlet boundary conditions has features suggestive ... More
Connections between M-theory and superstringsDec 19 1997This article reviews the non-perturbative structure of certain higher derivative terms in the type II string theory effective action and their connection to one-loop effects in eleven-dimensional supergravity compactified on a torus. New material is also ... More
Comments on Three-BranesFeb 15 1996Feb 21 1996The Born--Infeld-like effective world-volume theory of a single 3-brane is deduced from a manifestly space-time supersymmetric description of the corresponding $D$-brane. This is shown to be invariant under $SL(2,R)$ transformations that act on the abelian ... More
The Highly Damped Quasinormal Modes of Extremal Reissner-Nordström and Reissner-Nordström-de Sitter Black HolesAug 09 2007Apr 03 2008We analyze in detail the highly damped quasinormal modes of $D$-dimensional extremal Reissner-Nordstr$\ddot{\rm{o}}$m and Reissner-Nordstr$\ddot{\rm{o}}$m-de Sitter black holes. We only consider the extremal case where the event horizon and the Cauchy ... More
Instanton-induced Yang-Mills correlation functions at large N and their AdS_5xS^5 dualsDec 30 2002Correlation functions of chiral primary operators and their superconformal descendants in the N=4 supersymmetric SU(N) Yang-Mills theory are studied in detail in a one-instanton background and at large N. Whereas earlier calculations were restricted to ... More
Instantons and Non-renormalisation in AdS/CFTAug 03 1999Nov 23 1999The series of perturbative fluctuations around a multi-instanton contribution to a specific class of correlation functions of supercurrents in $\cal N=4$ supersymmetric SU(N) Yang-Mills theory is examined in the light of the AdS/CFT correspondence. Subject ... More
Non-perturbative Effects in AdS5 * S5 String Theory and d=4 SUSY Yang-MillsApr 27 1998Jun 10 1998We show that five-dimensional anti de-Sitter space remains a solution to low-energy type IIB supergravity when the leading higher-derivative corrections to the classical supergravity (which are non-perturbative in the string coupling) are included. Furthermore, ... More
D-instantons, Strings and M-theoryApr 21 1997Dec 15 1999The R^4 terms in the effective action for M-theory compactified on a two-torus are motivated by combining one-loop results in type II superstring theories with the Sl(2,Z) duality symmetry. The conjectured expression reproduces precisely the tree-level ... More
Tree Search vs Optimization Approaches for Map GenerationMar 27 2019Search-based procedural content generation uses stochastic global optimization algorithms to search spaces of game content. However, it has been found that tree search can be competitive with evolution on certain optimization problems. We investigate ... More
Generative Design in Minecraft (GDMC), Settlement Generation CompetitionMar 27 2018Jul 31 2018This paper introduces the settlement generation competition for Minecraft, the first part of the Generative Design in Minecraft challenge. The settlement generation competition is about creating Artificial Intelligence (AI) agents that can produce functional, ... More
Automated Playtesting with Procedural Personas through MCTS with Evolved HeuristicsFeb 19 2018This paper describes a method for generative player modeling and its application to the automatic testing of game content using archetypal player models called procedural personas. Theoretically grounded in psychological decision theory, procedural personas ... More
Intentional Computational Level DesignApr 18 2019The procedural generation of levels and content in video games is a challenging AI problem. Often such generation relies on an intelligent way of evaluating the content being generated so that constraints are satisfied and/or objectives maximized. In ... More
Critical window for the vacant set left by random walk on random regular graphsJan 10 2011We consider the simple random walk on a random d-regular graph with n vertices, and investigate percolative properties of the set of vertices not visited by the walk until time un, where u > 0 is a fixed positive parameter. It was shown in [arXiv:1012.5117] ... More
Exploring transcendentality in superstring amplitudesJun 04 2019Jul 10 2019It is well known that the low energy expansion of tree-level superstring scattering amplitudes satisfies a suitably defined version of maximum transcendentality. In this paper it is argued that there is a natural extension of this definition that applies ... More
KeyForge: Mitigating Email Breaches with Forward-Forgeable SignaturesApr 12 2019Email breaches are commonplace, and they expose a wealth of personal, business, and political data that may have devastating consequences. The current email system allows any attacker who gains access to your email to prove the authenticity of the stolen ... More
Identities between Modular Graph FormsMar 02 2016Sep 07 2017This paper investigates the relations between modular graph forms, which are generalizations of the modular graph functions that were introduced in earlier papers motivated by the structure of the low energy expansion of genus-one Type II superstring ... More
Superfield integrals in high dimensionsJun 20 2005We present an efficient, covariant, graph-based method to integrate superfields over fermionic spaces of high dimensionality. We illustrate this method with the computation of the most general sixteen-dimensional Majorana-Weyl integral in ten dimensions. ... More
An SL(2,Z) anomaly in IIB supergravity and its F-theory interpretationOct 20 1998May 04 1999The SL(2,Z) duality transformations of type IIB supergravity are shown to be anomalous in generic F-theory backgrounds due to the anomalous transformation of the phase of the chiral fermion determinant. The anomaly is partially cancelled provided the ... More
A Unifying Topological Action for Heterotic and Type II Superstring TheoriesJun 13 1996The heterotic and type II superstring actions are identified in different anomaly-free decompositions of a single topological sigma-model action depending on bosonic and fermionic coordinates, $X^\mu$ and $\r^A$ respectively, and of their topological ... More
Non-perturbative contributions to the plane-wave string mass matrixMar 09 2005Jan 13 2006D-instanton contributions to the mass matrix of arbitrary excited string states of type IIB string theory in the maximally supersymmetric plane-wave background are calculated to leading order in the string coupling using a supersymmetric light-cone boundary ... More
Non-perturbative effects in the BMN limit of N=4 supersymmetric Yang-MillsJun 24 2005Mar 17 2006One-instanton contributions to the correlation functions of two gauge-invariant single-trace operators in N=4 SU(N) Yang-Mills theory are studied in semi-classical approximation in the BMN limit. The most straightforward examples involve operators with ... More
I-Brane Inflow and Anomalous Couplings on D-BranesMay 06 1996We show that the anomalous couplings of $D$-brane gauge and gravitational fields to Ramond-Ramond tensor potentials can be deduced by a simple anomaly inflow argument applied to intersecting $D$-branes and use this to determine the eight-form gravitational ... More
Creating and understanding email communication networks to aid digital forensic investigationsJun 14 2018Digital forensic analysts depend on the ability to understand the social networks of the individuals they investigate. We develop a novel method for automatically constructing these networks from collected hard drives. We accomplish this by scanning the ... More
Bouchaud's model exhibits two different aging regimes in dimension oneOct 29 2002May 20 2005Let E_i be a collection of i.i.d. exponential random variables. Bouchaud's model on Z is a Markov chain X(t) whose transition rates are given by w_{ij}=\nu \exp(-\beta ((1-a)E_i-aE_j)) if i, j are neighbors in Z. We study the behavior of two correlation ... More
Generative Design in Minecraft: Chronicle ChallengeMay 14 2019We introduce the Chronicle Challenge as an optional addition to the Settlement Generation Challenge in Minecraft. One of the foci of the overall competition is adaptive procedural content generation (PCG), an arguably under-explored problem in computational ... More
Strichartz Estimates for the Schrödinger Equation with a Measure-Valued PotentialAug 08 2019We prove Strichartz estimates for the Schr\"odinger equation in $\mathbb R^n$, $n\geq 3$, with a Hamiltonian $H = -\Delta + \mu$. The perturbation $\mu$ is a compactly supported measure in $\mathbb R^n$ with dimension $\alpha > n-(1+\frac{1}{n-1})$. The ... More
DATA AgentSep 28 2018This paper introduces DATA Agent, a system which creates murder mystery adventures from open data. In the game, the player takes on the role of a detective tasked with finding the culprit of a murder. All characters, places, and items in DATA Agent games ... More
"Press Space to Fire": Automatic Video Game Tutorial GenerationMay 30 2018We propose the problem of tutorial generation for games, i.e. to generate tutorials which can teach players to play games, as an AI problem. This problem can be approached in several ways, including generating natural language descriptions of game rules, ... More
On the modular structure of the genus-one Type II superstring low energy expansionFeb 24 2015Jun 03 2015The analytic contribution to the low energy expansion of Type II string amplitudes at genus-one is a power series in space-time derivatives with coefficients that are determined by integrals of modular functions over the complex structure modulus of the ... More
String theory dualities and supergravity divergencesFeb 19 2010Oct 24 2013We demonstrate how duality invariance of the low energy expansion of the four-graviton amplitude in type II string theory determines the precise coefficients of multiloop logarithmic ultraviolet divergences of maximal supergravity in various dimensions. ... More
Automorphic properties of low energy string amplitudes in various dimensionsJan 14 2010Apr 01 2010This paper explores the moduli-dependent coefficients of higher derivative interactions that appear in the low-energy expansion of the four-graviton amplitude of maximally supersymmetric string theory compactified on a d-torus. These automorphic functions ... More
D-brane interactions in type IIB plane-wave backgroundMay 17 2002Jul 01 2002The cylinder diagrams that determine the static interactions between pairs of Dp-branes in the type IIB plane wave background are evaluated. The resulting expressions are elegant generalizations of the flat-space formulae that depend on the value of the ... More
Two loops in eleven dimensionsOct 06 1999Sep 19 2005The two-loop Feynman diagram contribution to the four-graviton amplitude of eleven-dimensional supergravity compactified on a two-torus, T^2, is analyzed in detail. The Schwinger parameter integrations are re-expressed as integration over the moduli space ... More
Resolved energy budget of superstructures in Rayleigh-Bénard convectionMay 24 2019Turbulent flows in nature often exhibit large-scale flow structures despite the presence of small-scale fluctuations. These so-called turbulent superstructures play a crucial role in many geo- and astrophysical flows. In turbulent Rayleigh-B\'{e}nard ... More
Data-Driven Debugging for Functional Side ChannelsAug 30 2018Functional side channels arise when an attacker knows that the secret value of a server stays fixed for a certain time, and can observe the server executes on a sequence of different public inputs, each paired with the same secret input. Thus for each ... More
Quantitative Mitigation of Timing Side ChannelsJun 21 2019Timing side channels pose a significant threat to the security and privacy of software applications. We propose an approach for mitigating this problem by decreasing the strength of the side channels as measured by entropy-based objectives, such as min-guess ... More
Universality of the REM for dynamics of mean-field spin glassesJun 14 2007We consider a version of a Glauber dynamics for a p-spin Sherrington--Kirkpatrick model of a spin glass that can be seen as a time change of simple random walk on the N-dimensional hypercube. We show that, for any p>2 and any inverse temperature \beta>0, ... More
The Class 0 Protostar BHR71: Herschel Observations and Dust Continuum ModelsJan 03 2017We use Herschel spectrophotometry of BHR71, an embedded Class 0 protostar, to provide new constraints on its physical properties. We detect 645 (non-unique) spectral lines amongst all spatial pixels. At least 61 different spectral lines originate from ... More
Nucleon structure with pion mass down to 149 MeVNov 01 2012We present isovector nucleon observables: the axial, tensor, and scalar charges and the Dirac radius. Using the BMW clover-improved Wilson action and pion masses as low as 149 MeV, we achieve good control over chiral extrapolation to the physical point. ... More
Computing the nucleon charge and axial radii directly at $Q^2=0$ in lattice QCDNov 30 2017We describe a procedure for extracting momentum derivatives of nucleon matrix elements on the lattice directly at $Q^2=0$. This is based on the Rome method for computing momentum derivatives of quark propagators. We apply this procedure to extract the ... More
Oblique and curved D-branes in IIB plane-wave string theoryJun 06 2003Oblique Dp-branes in the maximally supersymmetric type IIB plane-wave background are constructed in terms of boundary states, as well as from the open string point of view. These Dp-branes, whose existence was anticipated by Hikida and Yamaguchi from ... More
Nucleon axial, scalar, and tensor charges using lattice QCD at the physical pion massMar 15 2019May 16 2019We report on lattice QCD calculations of the nucleon isovector axial, scalar, and tensor charges. Our calculations are performed on two 2+1-flavor ensembles generated using a 2-HEX-smeared Wilson-clover action at the physical pion mass and lattice spacings ... More
Nucleon electromagnetic form factors at high $Q^2$ from Wilson-clover fermionsOct 09 2018We present results on the nucleon electromagnetic form factors from Lattice QCD at momentum transfer up to about $12$~GeV$^2$. We analyze two gauge ensembles with the Wilson-clover fermion action, a lattice spacing of $a\approx 0.09$~fm and pion masses ... More
Directed random walk on the backbone of an oriented percolation clusterApr 13 2012Jun 17 2013We consider a directed random walk on the backbone of the infinite cluster generated by supercritical oriented percolation, or equivalently the space-time embedding of the ``ancestral lineage'' of an individual in the stationary discrete-time contact ... More
Type-directed Bounding of Collections in Reactive ProgramsOct 24 2018Jan 28 2019Our aim is to statically verify that in a given reactive program, the length of collection variables does not grow beyond a given bound. We propose a scalable type-based technique that checks that each collection variable has a given refinement type that ... More
Generating heavy particles with energy and momentum conservationJan 17 2011We propose a novel algorithm, called REGGAE, for the generation of momenta of a given sample of particle masses, evenly distributed in Lorentz invariant phase space and obeying energy and momentum conservation. In comparison to other existing algorithms, ... More
The Cameron-Erdos ConjectureApr 04 2003A set A of integers is said to be sum-free if there are no solutions to the equation x + y = z with x,y and z all in A. Answering a question of Cameron and Erdos, we show that the number of sum-free subsets of {1,...,N} is O(2^(N/2)).
An Essay on the Application of mathematical Analysis to the theories of Electricity and MagnetismJul 01 2008Green's famous essay (Nottingham, 1828), with which he introduced the potential function, was transcribed from its reprint in Crelle's Journal (1850-54), with several typographical corrections and a reference section added. Green starts with accounts ... More
Systematics in nucleon matrix element calculationsDec 26 2018The current status of calculations of simple nucleon structure observables is reviewed, with a focus on the axial charge. A major challenge is the combination of an exponentially decaying signal-to-noise ratio and the need for large source-sink separations ... More
Roth's theorem in the primesFeb 25 2003Sep 07 2004We show that any set containing a positive proportion of the primes contains a 3-term arithmetic progression. An important ingredient is a proof that the primes enjoy the so-called Hardy-Littlewood majorant property. We derive this by giving a new proof ... More
HashGraph -- Scalable Hash Tables Using A Sparse Graph Data StructureJul 05 2019Hash tables are ubiquitous and used in a wide range of applications for efficient probing of large and unsorted data. If designed properly, hash-tables can enable efficients look ups in a constant number of operations or commonly referred to as O(1) operations. ... More
Tensor powers of rank 1 Drinfeld modules and periodsJun 12 2017We study tensor powers of rank 1 sign-normalized Drinfeld A-modules, where A is the coordinate ring of an elliptic curve over a finite field. Using the theory of A-motives, we find explicit formulas for the A-action of these modules. Then, by developing ... More
Special zeta values using tensor powers of Drinfeld modulesJun 19 2017Aug 30 2017We study tensor powers of rank 1 sign-normalized Drinfeld A-modules, where A is the coordinate ring of an elliptic curve over a finite field. Using the theory of vector valued Anderson generating functions, we give formulas for the coefficients of the ... More
On the Energy Decay Rate of the Fractional Wave Equation on $\mathbb{R}$ with Relatively Dense DampingApr 24 2019We establish upper bounds for the decay rate of the energy of the damped fractional wave equation when the averages of the damping coefficient on all intervals of a fixed length are bounded below. If the power of the fractional Laplacian, $s$, is between ... More
The Carina Nebula and Gum 31 molecular complex: I. Molecular gas distribution, column densities and dust temperaturesNov 24 2015We report high resolution observations of the $^{12}$CO$(1\rightarrow0)$ and $^{13}$CO$(1\rightarrow0)$ molecular lines in the Carina Nebula and the Gum 31 region obtained with the 22-m Mopra telescope as part of the The Mopra Southern Galactic Plane ... More
Scanning Quantum Dot MicroscopyMar 26 2015Interactions between atomic and molecular objects are to a large extent defined by the nanoscale electrostatic potentials which these objects produce. We introduce a scanning probe technique that enables three-dimensional imaging of local electrostatic ... More
Oscillator Based on Lumped Double Ladder Circuit with Band Edge DegeneracyOct 03 2016Mar 27 2017An oscillator design based on a periodic, double ladder resonant circuit is proposed. The circuit exhibits a degenerate band edge (DBE) in the dispersion diagram of its phase-frequency eigenstates, and possesses unique resonance features associated with ... More
Extension of ATLAST/LUVOIR's Capabilities to 5 Microns, or BeyondMay 14 2016ATLAST is a particular realization of LUVOIR, the Large Ultraviolet Optical Infrared telescope, a ~10 m diameter space telescope being defined for consideration in the 2020 Decadal Review of astronomy and astrophysics. ATLAST/LUVOIR is generally thought ... More
THz Field Control of In-Plane Orbital Order in La0.5Sr1.5MnO4Jun 04 2015Sep 23 2015In-plane anisotropic ground states are ubiquitous in correlated solids such as pnictides, cuprates and manganites. They can arise from doping Mott insulators and compete with phases such as superconductivity, however their origins are debated. Strong ... More
LSTM knowledge transfer for HRV-based sleep stagingSep 12 2018Automated sleep stage classification using heart-rate variability is an active field of research. In this work limitations of the current state-of-the-art are addressed through the use of deep learning techniques and their efficacy is demonstrated. First, ... More
Magnetic Field Uniformity Across the GF 9-2 YSO, L1082C Dense Core, and GF 9 Filamentary Dark CloudSep 14 2018The orientation of the magnetic field (B-field) in the filamentary dark cloud GF 9 was traced from the periphery of the cloud into the L1082C dense core that contains the low-mass, low-luminosity Class 0 young stellar object (YSO) GF 9-2 (IRAS 20503+6006). ... More
The Sloan Digital Sky Survey Stripe 82 Imaging Data: Depth-Optimized Co-adds Over 300 Deg^2 in Five FiltersMay 28 2014We present and release co-added images of the Sloan Digital Sky Survey (SDSS) Stripe 82. Stripe 82 covers an area of 300 deg^2 on the Celestial Equator, and has been repeatedly scanned 70-90 times in the ugriz bands by the SDSS imaging survey. By making ... More
Characterizing the Circumgalactic Medium of Nearby Galaxies with HST/COS and HST/STIS Absorption-Line Spectroscopy: II. Methods and ModelsApr 01 2017We present basic data and modeling for a survey of the cool, photo-ionized Circum-Galactic Medium (CGM) of low-redshift galaxies using far-UV QSO absorption line probes. This survey consists of "targeted" and "serendipitous" CGM subsamples, originally ... More
Will Central Counterparties become the New Rating Agencies?Nov 26 2012Nov 28 2012Central Counterparties (CCPs) are widely promoted as a requirement for safe banking with little dissent except on technical grounds (such as proliferation of CCPs). Whilst CCPs can have major operational positives, we argue that CCPs have many of the ... More
Regulatory-Optimal FundingOct 12 2013Aug 12 2014Funding is a cost to trading desks that they see as an input. Current FVA-related literature reflects this by also taking funding costs as an input, usually constant, and always risk-neutral. However, this funding curve is the output from a Treasury point ... More
VAR and ES/CVAR Dependence on data cleaning and Data Models: Analysis and ResolutionMay 29 2014Historical (Stressed-) Value-at-Risk ((S)VAR), and Expected Shortfall (ES), are widely used risk measures in regulatory capital and Initial Margin, i.e. funding, computations. However, whilst the definitions of VAR and ES are unambiguous, they depend ... More
The essential ideal in group cohomology does not square to zeroFeb 27 2003Sep 09 2003Let G be the Sylow 2-subgroup of the unitary group $SU_3(4)$. We find two essential classes in the mod-2 cohomology ring of G whose product is nonzero. In fact, the product is the ``last survivor'' of Benson-Carlson duality. Recent work of Pakianathan ... More
A revised catalogue of 294 Galactic supernova remnantsJul 04 2019Aug 01 2019A revised catalogue of Galactic supernova remnants (SNRs) is presented, along with some simple statistics of their properties. Six new SNRs have been added to the catalogue since the previous published version from 2014, and six entries have been removed, ... More
Warehousing Credit (CVA) Risk, Capital (KVA) and Tax (TVA) ConsequencesJul 11 2014Jan 07 2015Credit risk may be warehoused by choice, or because of limited hedging possibilities. Credit risk warehousing increases capital requirements and leaves open risk. Open risk must be priced in the physical measure, rather than the risk neutral measure, ... More
MVA: Initial Margin Valuation Adjustment by Replication and RegressionMay 02 2014Jan 12 2015Initial margin requirements are becoming an increasingly common feature of derivative markets. However, while the valuation of derivatives under collateralisation (Piterbarg 2010, Piterbarg2012), under counterparty risk with unsecured funding costs (FVA) ... More
The nil Temperley--Lieb algebra of type affine CMar 07 2017Mar 14 2019We introduce a type affine $C$ analogue of the nil Temperley--Lieb algebra, in terms of generators and relations. We show that this algebra $T(n)$, which is a quotient of the positive part of a Kac--Moody algebra of type $D_{n+1}^{(2)}$, has an easily ... More
A deterministic pseudorandom perturbation scheme for arbitrary polynomial predicatesAug 08 2013We present a symbolic perturbation scheme for arbitrary polynomial geometric predicates which combines the benefits of Emiris and Canny's simple randomized linear perturbation scheme with Yap's multiple infinitesimal scheme for general predicates. Like ... More
Integral traces of weak Maass forms of genus zero odd prime levelJul 08 2013Duke and the second author defined a family of linear maps from spaces of weakly holomorphic modular forms of negative integral weight and level 1 into spaces of weakly holomorphic modular forms of half integral weight and level 4 and showed that these ... More
Searches for Compositeness at the TevatronApr 28 2000Quark-quark and quark-lepton searches for compositenss at the Fermilab Tevatron are summarized. These are of the contact-interaction variety where sqrt(s-hat) < the hypothesized mass scales, Lambda. Tevatron experiments limit a variety of compositeness ... More
Testing Benson's Regularity ConjectureOct 11 2007Aug 13 2008D. J. Benson conjectures that the Castelnuovo-Mumford regularity of a group cohomology ring is always zero. More generally he conjectures that the cohomology ring always has a system of parameters satisfying a property he calls very strong quasi-regular. ... More
On Carlson's depth conjecture in group cohomologyJun 12 2002We establish a weak form of Carlson's conjecture on the depth of the mod-p cohomology ring of a p-group. In particular, Duflot's lower bound for the depth is tight if and only if the cohomology ring is not detected on a certain family of subgroups. The ... More
A colour scheme for the display of astronomical intensity imagesAug 25 2011Aug 30 2011I describe a colour scheme that is appropriate for the screen display of intensity images. This -- unlike many currently available schemes -- is designed to be monotonically increasing in terms of its perceived brightness. Also, when printed on a black ... More
Homology representations arising from the half cubeJun 09 2008Dec 04 2008We construct a CW decomposition $C_n$ of the $n$-dimensional half cube in a manner compatible with its structure as a polytope. For each $3 \leq k \leq n$, the complex $C_n$ has a subcomplex $C_{n, k}$, which coincides with the clique complex of the half ... More
The essential ideal is a Cohen-Macaulay moduleFeb 26 2004Let G be a finite p-group which does not contain a rank two elementary abelian p-group as a direct factor. Then the ideal of essential classes in the mod-p cohomology ring of G is a Cohen-Macaulay module whose Krull dimension is the p-rank of the centre ... More
HST STIS Observations of PG 0946+301: the Highest Quality UV Spectrum of a BALQSOJul 20 2001We describe deep (40 orbits) HST/STIS observations of the BALQSO PG 0946+301 and make them available to the community. These observations are the major part of a multi-wavelength campaign on this object aimed at determining the ionization equilibrium ... More
Gröbner bases for p-group algebrasOct 09 2009Experiment shows that the reverse length-lexicographical word ordering consistently yields far smaller Gr\"obner bases for modular p-group algebras than the length-lexicographical ordering. For the so-called Jennings word ordering, based on a special ... More
XVA at the Exercise BoundaryOct 02 2016XVA is a material component of a trade valuation and hence it must impact the decision to exercise options within a given netting set. This is true for both unsecured trades and secured / cleared trades where KVA and MVA play a material role even if CVA ... More
The Maintenance of Sex: Ronald Fisher meets the Red QueenApr 10 2013Apr 23 2013Sex in higher diploids carries a two-fold cost of males that should reduce its fitness relative to cloning and result in its extinction. Instead, sex is widespread and it is clonal species that face early obsolescence. One possible reason is that sex ... More
Generalized Temperley-Lieb algebras and decorated tanglesDec 04 1997We give presentations, by means of diagrammatic generators and relations, of the analogues of the Temperley-Lieb algebras associated as Hecke algebra quotients to Coxeter graphs of type B and $D$. This generalizes Kauffman's diagram calculus for the Temperley-Lieb ... More
Full heaps and representations of affine Kac--Moody algebrasMay 30 2006Apr 06 2007We give a combinatorial construction, not involving a presentation, of almost all untwisted affine Kac--Moody algebras modulo their one-dimensional centres in terms of signed raising and lowering operators on a certain distributive lattice ${\Cal B}$. ... More
A Standard Form for Incompressible Surfaces in a HandlebodySep 18 1996Let $\F$ be a compact surface and let $I$ be the unit interval. This paper gives a standard form for all 2-sided incompressible surfaces in the 3-manifold $\F \times I$. Since $\F \times I$ is a handlebody when $\F$ has boundary, this standard form applies ... More
A Hybrid Reasoning Model for Indirect AnswersJun 07 1994This paper presents our implemented computational model for interpreting and generating indirect answers to Yes-No questions. Its main features are 1) a discourse-plan-based approach to implicature, 2) a reversible architecture for generation and interpretation, ... More
Reconstructing toric quiver flag varieties from a tilting bundleJun 16 2017Oct 14 2017We prove that every toric quiver flag variety $Y$ is isomorphic to a fine moduli space of cyclic modules over the algebra $\text{End}(T)$ for some tilting bundle $T$ on $Y$. This generalises the well known fact that $\mathbb{P}^n$ can be recovered from ... More
Mid-Infrared Selection of Active GalaxiesOct 21 2004Mid-infrared photometry provides a robust technique for identifying active galaxies. While the ultraviolet to mid-infrared continuum of normal galaxies is dominated by the composite stellar black body curve and peaks at approximately 1.6 microns, the ... More
A GAS OF D-INSTANTONSApr 21 1995A D-instanton is a space-time event associated with world-sheet boundaries that contributes non-perturbative effects of order $e^{-const/\kappa}$ to closed-string amplitudes. Some properties of a gas of D-instantons are discussed in this paper.
Vacuum Values for Auxiliary String FieldsApr 27 1994Apr 27 1994Auxiliary string fields are introduced in light-cone gauge string field theory in order to express contact interactions as contractions of cubic vertices. The auxiliary field in the purely closed-string bosonic theory may be given a non-zero expectation ... More