9,351 research outputs found
Persistence of fractional Brownian motion with moving boundaries and applications
We consider various problems related to the persistence probability of
fractional Brownian motion (FBM), which is the probability that the FBM
stays below a certain level until time . Recently, Oshanin et al. study a
physical model where persistence properties of FBM are shown to be related to
scaling properties of a quantity , called steady-state current. It turns
out that for this analysis it is important to determine persistence
probabilities of FBM with a moving boundary. We show that one can add a
boundary of logarithmic order to a FBM without changing the polynomial rate of
decay of the corresponding persistence probability which proves a result needed
in Oshanin et al. Moreover, we complement their findings by considering the
continuous-time version of . Finally, we use the results for moving
boundaries in order to improve estimates by Molchan concerning the persistence
properties of other quantities of interest, such as the time when a FBM reaches
its maximum on the time interval or the last zero in the interval
.Comment: 13 page
A note on the regularity of matrices with uniform polynomial entries
In this text we study the regularity of matrices with special polynomial
entries. Barring some mild conditions we show that these matrices are regular
if a natural limit size is not exceeded. The proof draws connections to
generalized Vandermonde matrices and Schur polynomials that are discussed in
detail
Time-lagged autoencoders: Deep learning of slow collective variables for molecular kinetics
Inspired by the success of deep learning techniques in the physical and
chemical sciences, we apply a modification of an autoencoder type deep neural
network to the task of dimension reduction of molecular dynamics data. We can
show that our time-lagged autoencoder reliably finds low-dimensional embeddings
for high-dimensional feature spaces which capture the slow dynamics of the
underlying stochastic processes - beyond the capabilities of linear dimension
reduction techniques
On Gravity, Torsion and the Spectral Action Principle
We consider compact Riemannian spin manifolds without boundary equipped with
orthogonal connections. We investigate the induced Dirac operators and the
associated commutative spectral triples. In case of dimension four and totally
anti-symmetric torsion we compute the Chamseddine-Connes spectral action,
deduce the equations of motions and discuss critical points.Comment: minor modifications, some further typos fixe
Chess players' performance beyond 64 squares: A case study on the limitations of cognitive abilities transfer
In a beauty contest experiment with over 6,000 chess players, ranked from amateur to world class, we found that Grandmasters act very similar to other humans. This even holds true when they play exclusively against players of approximately their own strength. In line with psychological research on chess players' thinking, we argue that they are not more rational in a game theoretic sense per se. Their skills are rather specific for their game.chess, beauty contest, cognitive transfer
git2net - Mining Time-Stamped Co-Editing Networks from Large git Repositories
Data from software repositories have become an important foundation for the
empirical study of software engineering processes. A recurring theme in the
repository mining literature is the inference of developer networks capturing
e.g. collaboration, coordination, or communication from the commit history of
projects. Most of the studied networks are based on the co-authorship of
software artefacts defined at the level of files, modules, or packages. While
this approach has led to insights into the social aspects of software
development, it neglects detailed information on code changes and code
ownership, e.g. which exact lines of code have been authored by which
developers, that is contained in the commit log of software projects.
Addressing this issue, we introduce git2net, a scalable python software that
facilitates the extraction of fine-grained co-editing networks in large git
repositories. It uses text mining techniques to analyse the detailed history of
textual modifications within files. This information allows us to construct
directed, weighted, and time-stamped networks, where a link signifies that one
developer has edited a block of source code originally written by another
developer. Our tool is applied in case studies of an Open Source and a
commercial software project. We argue that it opens up a massive new source of
high-resolution data on human collaboration patterns.Comment: MSR 2019, 12 pages, 10 figure
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