Results for "Diederik P. Kingma"

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Fast Gradient-Based Inference with Continuous Latent Variable Models in Auxiliary FormJun 04 2013We propose a technique for increasing the efficiency of gradient-based inference and learning in Bayesian networks with multiple layers of continuous latent vari- ables. We show that, in many cases, it is possible to express such models in an auxiliary ... More
Weight Normalization: A Simple Reparameterization to Accelerate Training of Deep Neural NetworksFeb 25 2016Jun 04 2016We present weight normalization: a reparameterization of the weight vectors in a neural network that decouples the length of those weight vectors from their direction. By reparameterizing the weights in this way we improve the conditioning of the optimization ... More
Auto-Encoding Variational BayesDec 20 2013May 01 2014How can we perform efficient inference and learning in directed probabilistic models, in the presence of continuous latent variables with intractable posterior distributions, and large datasets? We introduce a stochastic variational inference and learning ... More
Efficient Gradient-Based Inference through Transformations between Bayes Nets and Neural NetsFeb 03 2014Jan 22 2015Hierarchical Bayesian networks and neural networks with stochastic hidden units are commonly perceived as two separate types of models. We show that either of these types of models can often be transformed into an instance of the other, by switching between ... More
Adam: A Method for Stochastic OptimizationDec 22 2014Jan 30 2017We introduce Adam, an algorithm for first-order gradient-based optimization of stochastic objective functions, based on adaptive estimates of lower-order moments. The method is straightforward to implement, is computationally efficient, has little memory ... More
Glow: Generative Flow with Invertible 1x1 ConvolutionsJul 09 2018Jul 10 2018Flow-based generative models (Dinh et al., 2014) are conceptually attractive due to tractability of the exact log-likelihood, tractability of exact latent-variable inference, and parallelizability of both training and synthesis. In this paper we propose ... More
An Introduction to Variational AutoencodersJun 06 2019Variational autoencoders provide a principled framework for learning deep latent-variable models and corresponding inference models. In this work, we provide an introduction to variational autoencoders and some important extensions.
Learning Sparse Neural Networks through $L_0$ RegularizationDec 04 2017Jun 22 2018We propose a practical method for $L_0$ norm regularization for neural networks: pruning the network during training by encouraging weights to become exactly zero. Such regularization is interesting since (1) it can greatly speed up training and inference, ... More
Note on Equivalence Between Recurrent Neural Network Time Series Models and Variational Bayesian ModelsApr 29 2015Jun 18 2016We observe that the standard log likelihood training objective for a Recurrent Neural Network (RNN) model of time series data is equivalent to a variational Bayesian training objective, given the proper choice of generative and inference models. This ... More
Improving Variational Inference with Inverse Autoregressive FlowJun 15 2016We propose a simple and scalable method for improving the flexibility of variational inference through a transformation with autoregressive networks. Autoregressive networks, such as RNNs and MADE, are very powerful models; however, ancestral sampling ... More
Variational Dropout and the Local Reparameterization TrickJun 08 2015Dec 20 2015We investigate a local reparameterizaton technique for greatly reducing the variance of stochastic gradients for variational Bayesian inference (SGVB) of a posterior over model parameters, while retaining parallelizability. This local reparameterization ... More
Variational Autoencoders and Nonlinear ICA: A Unifying FrameworkJul 10 2019The framework of variational autoencoders allows us to efficiently learn deep latent-variable models, such that the model's marginal distribution over observed variables fits the data. Often, we're interested in going a step further, and want to approximate ... More
Markov Chain Monte Carlo and Variational Inference: Bridging the GapOct 23 2014May 19 2015Recent advances in stochastic gradient variational inference have made it possible to perform variational Bayesian inference with posterior approximations containing auxiliary random variables. This enables us to explore a new synthesis of variational ... More
Adam: A Method for Stochastic OptimizationDec 22 2014Jul 23 2015We introduce Adam, an algorithm for first-order gradient-based optimization of stochastic objective functions, based on adaptive estimates of lower-order moments. The method is straightforward to implement, is computationally efficient, has little memory ... More
PixelCNN++: Improving the PixelCNN with Discretized Logistic Mixture Likelihood and Other ModificationsJan 19 2017PixelCNNs are a recently proposed class of powerful generative models with tractable likelihood. Here we discuss our implementation of PixelCNNs which we make available at Our implementation contains a number of modifications ... More
Semi-Supervised Learning with Deep Generative ModelsJun 20 2014Oct 31 2014The ever-increasing size of modern data sets combined with the difficulty of obtaining label information has made semi-supervised learning one of the problems of significant practical importance in modern data analysis. We revisit the approach to semi-supervised ... More
Improving Variational Inference with Inverse Autoregressive FlowJun 15 2016Jan 30 2017The framework of normalizing flows provides a general strategy for flexible variational inference of posteriors over latent variables. We propose a new type of normalizing flow, inverse autoregressive flow (IAF), that, in contrast to earlier published ... More
Relativity Theory RefoundedNov 27 2015We put forward a new view of relativity theory that makes the existence of a flow of time compatible with the four-dimensional block universe. To this end, we apply the creation-discovery view elaborated for quantum mechanics to relativity theory and ... More
Quantum Theory and Human Perception of the Macro-WorldMar 17 2014May 29 2014We investigate the question of 'why customary macroscopic entities appear to us humans as they do, i.e. as bounded entities occupying space and persisting through time', starting from our knowledge of quantum theory, how it affects the behavior of such ... More
Variational Lossy AutoencoderNov 08 2016Representation learning seeks to expose certain aspects of observed data in a learned representation that's amenable to downstream tasks like classification. For instance, a good representation for 2D images might be one that describes only global structure ... More
Variational Lossy AutoencoderNov 08 2016Mar 04 2017Representation learning seeks to expose certain aspects of observed data in a learned representation that's amenable to downstream tasks like classification. For instance, a good representation for 2D images might be one that describes only global structure ... More
Quantum Particles as Conceptual Entities: A Possible Explanatory Framework for Quantum TheoryApr 15 2010We put forward a possible new interpretation and explanatory framework for quantum theory. The basic hypothesis underlying this new framework is that quantum particles are conceptual entities. More concretely, we propose that quantum particles interact ... More
The dynamics of star-forming regions - which mechanisms set the cluster formation efficiency?Jul 11 2011The fraction of star formation that results in bound stellar clusters (cluster formation efficiency or CFE) is a central quantity in many studies of star formation, star clusters and galaxies. Recent results suggest that contrary to popular assumption, ... More
Spin and Wind Directions: Identifying Entanglement in Nature and CognitionJul 31 2015Aug 20 2015We performed a cognitive experiment in which we asked the participants to pick a pair of directions they considered as the 'preferred good example of two different wind directions'. The results of the experiment reveal that the 'Clauser Horne Shimony ... More
A Contextual Risk Model for the Ellsberg ParadoxMay 09 2011The Allais and Ellsberg paradoxes show that the expected utility hypothesis and Savage's Sure-Thing Principle are violated in real life decisions. The popular explanation in terms of 'ambiguity aversion' is not completely accepted. On the other hand, ... More
Contextual Risk and Its Relevance in EconomicsMay 09 2011Uncertainty in economics still poses some fundamental problems illustrated, e.g., by the Allais and Ellsberg paradoxes. To overcome these difficulties, economists have introduced an interesting distinction between 'risk' and 'ambiguity' depending on the ... More
A Cross-disciplinary Framework for the Description of Contextually Mediated ChangeJun 01 2007We present a mathematical framework (referred to as Context-driven Actualization of Potential, or CAP) for describing how entities change over time under the influence of a context. The approach facilitates comparison of change of state of entities studied ... More
Evolution as context-driven actualization of potential: Toward an interdisciplinary theory of change of stateNov 05 2005It is increasingly evident that there is more to biological evolution than natural selection; moreover, the concept of evolution is not limited to biology. We propose an integrative framework for characterizing how entities evolve, in which evolution ... More
General sGoldstino InflationAug 12 2016We prove that all inflationary models, including those with dark energy after the end of inflation, can be embedded in minimal supergravity with a single chiral superfield. Moreover, the amount of supersymmetry breaking is independently tunable due to ... More
Are globular clusters the natural outcome of regular high-redshift star formation?Sep 09 2015We summarise some of the recent progress in understanding the formation and evolution of globular clusters (GCs) in the context of galaxy formation and evolution. It is discussed that an end-to-end model for GC formation and evolution should capture four ... More
On the fraction of star formation occurring in bound stellar clustersAug 14 2012We present a theoretical framework in which bound stellar clusters arise naturally at the high-density end of the hierarchy of the interstellar medium (ISM). Due to short free-fall times, these high-density regions achieve high local star formation efficiencies, ... More
Collateral Damage: the Implications of Utrecht Star Cluster Astrophysics for Galaxy EvolutionJun 06 2012Until the early 2000s, the research portfolio of the Astronomical Institute in Utrecht (SIU) did not include galaxy evolution. Somewhat serendipitously, this changed with the advent of the star cluster group. In only a few years, a simple framework was ... More
A galactic-scale origin for stellar clusteringAug 31 2012We recently presented a model for the cluster formation efficiency (CFE), i.e. the fraction of star formation occurring in bound stellar clusters. It utilizes the idea that the formation of stars and stellar clusters occurs across a continuous spectrum ... More
Towards a multi-scale understanding of the gas-star formation cycle in the Central Molecular ZoneSep 26 2016The Central Molecular Zone (CMZ, the central 500 pc of the Milky Way) contains the largest reservoir of high-density molecular gas in the Galaxy, but forms stars at a rate 10-100 times below commonly-used star formation relations. We discuss recent efforts ... More
Contextualizing concepts using a mathematical generalization of the quantum formalismOct 29 2013Nov 01 2013We outline the rationale and preliminary results of using the state context property (SCOP) formalism, originally developed as a generalization of quantum mechanics, to describe the contextual manner in which concepts are evoked, used and combined to ... More
A Theory of Concepts and Their Combinations I: The Structure of the Sets of Contexts and PropertiesFeb 26 2004We propose a theory for modeling concepts that uses the state-context-property theory (SCOP), a generalization of the quantum formalism, whose basic notions are states, contexts and properties. This theory enables us to incorporate context into the mathematical ... More
Concepts and Their Dynamics: A Quantum-Theoretic Modeling of Human ThoughtJun 05 2012Jan 05 2013We analyze different aspects of our quantum modeling approach of human concepts, and more specifically focus on the quantum effects of contextuality, interference, entanglement and emergence, illustrating how each of them makes its appearance in specific ... More
Color-Magnitude Relations within Globular Cluster Systems of Giant Elliptical Galaxies: The Effects of Globular Cluster Mass Loss and the Stellar Initial Mass FunctionOct 21 2013Oct 28 2013Several recent studies have provided evidence for a `bottom-heavy' stellar initial mass function (IMF) in massive elliptical galaxies. Here we investigate the influence of the IMF shape on the recently discovered color-magnitude relation (CMR) among globular ... More
A Case for Applying an Abstracted Quantum Formalism to CognitionApr 11 2004This chapter outlines some of the highlights of efforts undertaken by our group to describe the role of contextuality in the conceptualization of conscious experience using generalized formalisms from quantum mechanics.
The Optical Colors of Giant Elliptical Galaxies and their Metal-Rich Globular Clusters Indicate a Bottom-Heavy Initial Mass FunctionNov 21 2012Jan 02 2013We report a systematic and statistically significant offset between the optical (g-z or B-I) colors of seven massive elliptical galaxies and the mean colors of their associated massive metal-rich globular clusters (GCs) in the sense that the parent galaxies ... More
Fast and inefficient star formation due to short-lived molecular clouds and rapid feedbackMay 21 2019May 23 2019The physics of star formation and the deposition of mass, momentum, and energy into the interstellar medium by massive stars (`feedback') are the main uncertainties in modern cosmological simulations of galaxy formation and evolution. These processes ... More
Intrinsic Contextuality as the Crux of ConsciousnessOct 29 2013A stream of conscious experience is extremely contextual; it is impacted by sensory stimuli, drives and emotions, and the web of associations that link, directly or indirectly, the subject of experience to other elements of the individual's worldview. ... More
Many-field Inflation: Universality or Prior Dependence?Jul 18 2019We investigate the observational signatures of many-field inflation and present analytic expressions for the spectral index as a function of the prior. For a given prior we employ the central limit theorem and the horizon crossing approximation to derive ... More
The Quantum Nature of Identity in Human Thought: Bose-Einstein Statistics for Conceptual IndistinguishabilityOct 24 2014Increasing experimental evidence shows that humans combine concepts in a way that violates the rules of classical logic and probability theory. On the other hand, mathematical models inspired by the formalism of quantum theory are in accordance with data ... More
Inflation by AlignmentDec 04 2014Mar 17 2015Pseudo-Goldstone bosons (pGBs) can provide technically natural inflatons, as has been comparatively well-explored in the simplest axion examples. Although inflationary success requires trans-Planckian decay constants, f > Mp, several mechanisms have been ... More
A Geometric Formulation of SupersymmetrySep 23 2016The scalar fields of supersymmetric models are coordinates of a geometric space. We propose a formulation of supersymmetry that is covariant with respect to reparametrizations of this target space. Employing chiral multiplets as an example, we introduce ... More
Toward a Formal Model of the Shifting Relationship between Concepts and Contexts during Associative ThoughtOct 29 2013The quantum inspired State Context Property (SCOP) theory of concepts is unique amongst theories of concepts in offering a means of incorporating that for each concept in each different context there are an unlimited number of exemplars, or states, of ... More
Transfer Learning Across Simulated Robots With Different SensorsJul 18 2019For a robot to learn a good policy, it often requires expensive equipment (such as sophisticated sensors) and a prepared training environment conducive to learning. However, it is seldom possible to perfectly equip robots for economic reasons, nor to ... More
Quantum cognition goes beyond-quantum: modeling the collective participant in psychological measurementsFeb 24 2018In psychological measurements, two levels should be distinguished: the 'individual level', relative to the different participants in a given cognitive situation, and the 'collective level', relative to the overall statistics of their outcomes, which we ... More
On the Conceptuality Interpretation of Quantum and Relativity TheoriesNov 27 2017How can we explain the strange behavior of quantum and relativistic entities? Why do they behave in ways that defy our intuition about how physical entities should behave, considering our ordinary experience of the world around us? In this article, we ... More
The initial mass spectrum of old globular clusters in dwarf galaxiesOct 18 2011We test whether the masses of old globular clusters (GCs) in dwarf galaxies are consistent with the same initial mass spectrum as young massive clusters (YMCs) in nearby star-forming galaxies. The most massive GCs of dwarf galaxies are compared to their ... More
Prevalent externally-driven protoplanetary disc dispersal as a function of the galactic environmentJul 10 2019The stellar birth environment can significantly shorten protoplanetary disc (PPD) lifetimes due to the influence of stellar feedback mechanisms. The degree to which these mechanisms suppress the time and mass available for planet formation is dependent ... More
Probing the role of the galactic environment in the formation of stellar clusters; using M83 as a test benchMay 27 2015Jun 16 2015We present a study of the M83 cluster population, covering the disc of the galaxy between radii of 0.45 and 4.5 kpc. We aim to probe the properties of the cluster population as a function of distance from the galactic centre. We observe a net decline ... More
Quantum cognition beyond Hilbert space II: ApplicationsApr 27 2016The research on human cognition has recently benefited from the use of the mathematical formalism of quantum theory in Hilbert space. However, cognitive situations exist which indicate that the Hilbert space structure, and the associated Born rule, would ... More
Deeply Embedded Protostellar Population in the 20 km s-1 Cloud of the Central Molecular ZoneOct 16 2015We report the discovery of a population of deeply embedded protostellar candidates in the 20 km s$^{-1}$ cloud, one of the massive molecular clouds in the Central Molecular Zone (CMZ) of the Milky Way, using interferometric submillimeter continuum and ... More
A Potentiality and Conceptuality Interpretation of Quantum PhysicsMay 20 2010We elaborate on a new interpretation of quantum mechanics which we introduced recently. The main hypothesis of this new interpretation is that quantum particles are entities interacting with matter conceptually, which means that pieces of matter function ... More
Universality classes of inflationSep 05 2013Dec 23 2013We investigate all single-field, slow-roll inflationary models whose slow-roll parameters scale as 1/N in the limit of a large number of e-folds N. We proof that all such models belong to two universality classes, characterised by a single parameter. ... More
Interpreting Quantum Particles as Conceptual EntitiesApr 15 2010We elaborate an interpretation of quantum physics founded on the hypothesis that quantum particles are conceptual entities playing the role of communication vehicles between material entities composed of ordinary matter which function as memory structures ... More
Fossil stellar streams and their globular cluster populations in the E-MOSAICS simulationsOct 23 2018Stellar haloes encode a fossil record of a galaxy's accretion history, generally in the form of structures of low surface brightness, such as stellar streams. While their low surface brightness makes it challenging to determine their age, metallicity, ... More
Context and Interference Effects in the Combinations of Natural ConceptsDec 19 2016The mathematical formalism of quantum theory exhibits significant effectiveness when applied to cognitive phenomena that have resisted traditional (set theoretical) modeling. Relying on a decade of research on the operational foundations of micro-physical ... More
Testing Quantum Models of Conjunction Fallacy on the World Wide WebSep 25 2016Jun 02 2017The 'conjunction fallacy' has been extensively debated by scholars in cognitive science and, in recent times, the discussion has been enriched by the proposal of modeling the fallacy using the quantum formalism. Two major quantum approaches have been ... More
M-theory and Gauged SupergravitiesAug 23 2004Aug 31 2004We present a pedagogical discussion of the emergence of gauged supergravities from M-theory. First, a review of maximal supergravity and its global symmetries and supersymmetric solutions is given. Next, different procedures of dimensional reduction are ... More
Gaugings at angles from orientifold reductionsFeb 03 2009Jun 10 2009We consider orientifold reductions to N=4 gauged supergravity in four dimensions. A special feature of this theory is that different factors of the gauge group can have relative angles with respect to the electro-magnetic SL(2) symmetry. These are crucial ... More
Bit-Swap: Recursive Bits-Back Coding for Lossless Compression with Hierarchical Latent VariablesMay 16 2019The bits-back argument suggests that latent variable models can be turned into lossless compression schemes. Translating the bits-back argument into efficient and practical lossless compression schemes for general latent variable models, however, is still ... More
Bit-Swap: Recursive Bits-Back Coding for Lossless Compression with Hierarchical Latent VariablesMay 16 2019Jun 05 2019The bits-back argument suggests that latent variable models can be turned into lossless compression schemes. Translating the bits-back argument into efficient and practical lossless compression schemes for general latent variable models, however, is still ... More
Bit-Swap: Recursive Bits-Back Coding for Lossless Compression with Hierarchical Latent VariablesMay 16 2019Jun 10 2019The bits-back argument suggests that latent variable models can be turned into lossless compression schemes. Translating the bits-back argument into efficient and practical lossless compression schemes for general latent variable models, however, is still ... More
The Formation and Early Evolution of Young Massive ClustersJan 16 2014We review the formation and early evolution of the most massive and dense young stellar clusters, focusing on the role they can play in our understanding of star and planet formation as a whole. Young massive cluster (YMC) progenitor clouds in the Galactic ... More
Universality Classes of Scale Invariant InflationJul 13 2015We investigate the inflationary implications of extensions of Poincare symmetry. The simplest constructions with local scale invariance lead to universal predictions: the spectral index is $n_s = 1-2/N$, in excellent agreement with Planck data, while ... More
Cosmological Attractors from $α$-Scale SupergravityMar 26 2015Sep 16 2015The Planck value of the spectral index can be interpreted as $n_s = 1 - 2/N$ in terms of the number of e-foldings $N$. An appealing explanation for this phenomenological observation is provided by $\alpha$-attractors: the inflationary predictions of these ... More
Quantum Model Theory (QMod): Modeling Contextual Emergent Entangled Interfering EntitiesApr 21 2012Aug 11 2012In this paper we present 'Quantum Model Theory' (QMod), a theory we developed to model entities that entail the typical quantum effects of 'contextuality', 'superposition', 'interference', 'entanglement' and 'emergence'. The aim of QMod is to put forward ... More
An uncertainty principle for star formation - II. A new method for characterising the cloud-scale physics of star formation and feedback across cosmic historyApr 30 2018Sep 04 2018The cloud-scale physics of star formation and feedback represent the main uncertainty in galaxy formation studies. Progress is hampered by the limited empirical constraints outside the restricted environment of the Local Group. In particular, the poorly-quantified ... More
Twin SupergravitiesApr 08 2009Jul 13 2009We study the phenomenon that pairs of supergravities can have identical bosonic field content but different fermionic extensions. Such twin theories are classified and shown to originate as truncations of a common theory with more supersymmetry. Moreover, ... More
Extended Symmetries in Supergravity: the Semi-simple CaseMay 16 2008Jul 04 2008The bosonic sector of various supergravity theories reduces to a homogeneous space G/H in three dimensions. The corresponding algebras g are simple for (half-)maximal supergravity, but can be semi-simple for other theories. We extend the existing literature ... More
The minimum metallicity of globular clusters and its physical origin -- implications for the galaxy mass-metallicity relation and observations of proto-globular clusters at high redshiftApr 22 2019In the local Universe, globular clusters (GCs) with metallicities $[{\rm Fe}/{\rm H}]<-2.5$ are extremely rare. In this Letter, the close connection between GC formation and galaxy evolution is used to show that this GC metallicity `floor' results from ... More
General sGoldstino InflationAug 12 2016Oct 25 2016We prove that all inflationary models, including those with dark energy after the end of inflation, can be embedded in minimal supergravity with a single chiral superfield. Moreover, the amount of supersymmetry breaking is independently tunable due to ... More
From Ambiguity Aversion to a Generalized Expected Utility. Modeling Preferences in a Quantum Probabilistic FrameworkOct 30 2015Ambiguity and ambiguity aversion have been widely studied in decision theory and economics both at a theoretical and an experimental level. After Ellsberg's seminal studies challenging subjective expected utility theory (SEUT), several (mainly normative) ... More
An uncertainty principle for star formation - IV. On the nature and filtering of diffuse emissionOct 26 2018Diffuse emission is observed in galaxies in many tracers across the electromagnetic spectrum, including tracers of star formation, such as H$\alpha$ and ultraviolet (UV), and tracers of gas mass, such as carbon monoxide (CO) transition lines and the 21-cm ... More
Metastable supersymmetry breaking in extended supergravityDec 16 2010Jul 28 2011We consider the stability of non-supersymmetric critical points of general N=4 supergravities. A powerful method to analyse this issue based on the sGoldstino direction has been developed for minimal supergravity. We adapt this to the present case, and ... More
Emulation of CPU-demanding reactive transport models: comparison of Gaussian processes, polynomial chaos expansion and deep neural networksSep 19 2018This paper presents a detailed comparison between 3 methods for emulating CPU-intensive reactive transport models (RTMs): Gaussian processes (GP), polynomial chaos expansion (PCE) and deep neural networks (DNNs). Besides direct emulation of the simulated ... More
Entanglement of Conceptual Entities in Quantum Model Theory (QMod)Apr 22 2012We have recently elaborated 'Quantum Model Theory' (QMod) to model situations where the quantum effects of contextuality, interference, superposition, entanglement and emergence, appear without the entities giving rise to these situations having necessarily ... More
Exorcising the Ostrogradsky ghost in coupled systemsApr 06 2016Sep 15 2016The Ostrogradsky theorem implies that higher-derivative terms of a single mechanical variable are either trivial or lead to additional, ghost-like degrees of freedom. In this letter we systematically investigate how the introduction of additional variables ... More
What is Quantum? Unifying Its Micro-Physical and Structural AppearanceMay 29 2014We can recognize two modes in which 'quantum appears' in macro domains: (i) a 'micro-physical appearance', where quantum laws are assumed to be universal and they are transferred from the micro to the macro level if suitable 'quantum coherence' conditions ... More
Globular cluster formation in the context of galaxy formation and evolutionJul 10 2014Sep 09 2015The formation of globular clusters (GCs) remains one of the main unsolved problems in star and galaxy formation. The past decades have seen important progress in constraining the physics of GC formation from a variety of directions. In this review, we ... More
The Current State of Cluster Formation SimulationsApr 16 2013Numerical simulations of star cluster formation have advanced greatly during the past decade, covering increasingly massive gas clouds while accounting for more and more complex physics. In this review, I discuss the present state of the field, paying ... More
Explaining the mass-to-light ratios of globular clustersJun 04 2008Jun 23 2008The majority of observed mass-to-light ratios of globular clusters are too low to be explained by `canonical' cluster models, in which dynamical effects are not accounted for. Moreover, these models do not reproduce a recently reported trend of increasing ... More
A Theory of Concepts and Their Combinations II: A Hilbert Space RepresentationFeb 26 2004The sets of contexts and properties of a concept are embedded in the complex Hilbert space of quantum mechanics. States are unit vectors or density operators, and contexts and properties are orthogonal projections. The way calculations are done in Hilbert ... More
Non-propagating degrees of freedom in supergravity and very extended G_2Jun 05 2007Nov 05 2007Recently a correspondence between non-propagating degrees of freedom in maximal supergravity and the very extended algebra E_11 has been found. We perform a similar analysis for a supergravity theory with eight supercharges and very extended G_2. In particular, ... More
Representation of State Property SystemsNov 15 2008A 'state property system' is the mathematical structure which models an arbitrary physical system by means of its set of states, its set of properties, and a relation of 'actuality of a certain property for a certain state'. We work out a new axiomatization ... More
A Model for the Onset of Self-gravitation and Star Formation in Molecular Gas Governed by Galactic Forces: I. Cloud-scale Gas MotionsDec 18 2017Modern extragalactic molecular gas surveys now reach the scales of star-forming giant molecular clouds (GMCs, 20-50 pc). Systematic variations in GMC properties with galaxy environment imply that clouds are not universally self-gravitating objects, decoupled ... More
De Sitter in Extended SupergravityDec 22 2009We show that known de Sitter solutions in extended gauged supergravity theories are interrelated via a web of supersymmetry-breaking truncations. In particular, all N=8 models reduce to a subset of the N=4 possibilities. Furthermore, a different subset ... More
Globular clusters as the relics of regular star formation in 'normal' high-redshift galaxiesSep 07 2015We present an end-to-end, two-phase model for the origin of globular clusters (GCs). In the model, populations of stellar clusters form in the high-pressure discs of high-redshift ($z>2$) galaxies (a rapid-disruption phase due to tidal perturbations from ... More
The evolution of the stellar mass function in star clustersOct 24 2009(Abridged) The dynamical ejection of stars from star clusters affects the shape of the stellar mass function (MF) in these clusters, because the escape probability of a star depends on its mass. The objective of this paper is to provide and to apply a ... More
Distilling the Essence of an Evolutionary Process and Implications for a Formal Description of CultureSep 18 2013It has been proposed that, since the origin of life and the ensuing evolution of biological species, a second evolutionary process has appeared on our planet. It is the evolution of culture-e.g., ideas, beliefs, and artifacts. Does culture evolve in the ... More
Contextualizing Concepts using a Mathematical Generalization of the Quantum FormalismMay 26 2002Aug 06 2004We outline the rationale and preliminary results of using the State Context Property (SCOP) formalism, originally developed as a generalization of quantum mechanics, to describe the contextual manner in which concepts are evoked, used, and combined to ... More
A model of the emergence and evolution of integrated worldviewsJan 09 2010It is proposed that the ability of humans to flourish in diverse environments and evolve complex cultures reflects the following two underlying cognitive transitions. The transition from the coarse-grained associative memory of Homo habilis to the fine-grained ... More
State Property Systems and Closure Spaces: Extracting the Classical and Nonclassical PartsApr 12 2004We introduce classical properties using the concept of super selection rule, i.e. two properties are separated by a superselection rule iff there do not exist 'superposition states' related to these two properties. Then we show that the classical properties ... More
The Molecular Wind in the Nearest Seyfert Galaxy Circinus Revealed by ALMASep 20 2016We present ALMA observations of the inner 1' (1.2 kpc) of the Circinus galaxy, the nearest Seyfert. We target CO (1-0) in the region associated with a well-known multiphase outflow driven by the central active galactic nucleus (AGN). While the geometry ... More
The large-N running of the spectral index of inflationFeb 10 2014May 24 2014We extend previous classifications of inflationary models by means of their behaviour at large-N, where N is the number of e-foldings. In addition to the perturbative 1/N case, whose slow-roll parameters fall off as powers of 1/N, we introduce the constant, ... More
Protoplanetary disc evolution affected by star-disc interactions in young stellar clustersApr 07 2014Most stars form in a clustered environment. Therefore, it is important to assess how this environment influences the evolution of protoplanetary discs around young stars. In turn, this affects their ability to produce planets and ultimately life. We present ... More
High-velocity stars in the cores of globular clusters: The illustrative case of NGC 2808May 17 2012We report the detection of five high-velocity stars in the core of the globular cluster NGC 2808. The stars lie on the the red giant branch and show total velocities between 40 and 45 km/s. For a core velocity dispersion sigma_c = 13.4 km/s, this corresponds ... More