2,104 research outputs found
On -cycles of graphs
Let be a finite undirected graph. Orient the edges of in an
arbitrary way. A -cycle on is a function such
for each edge , and are circulations on , and
whenever and have a common vertex. We show that each
-cycle is a sum of three special types of -cycles: cycle-pair -cycles,
Kuratowski -cycles, and quad -cycles. In case that the graph is
Kuratowski connected, we show that each -cycle is a sum of cycle-pair
-cycles and at most one Kuratowski -cycle. Furthermore, if is
Kuratowski connected, we characterize when every Kuratowski -cycle is a sum
of cycle-pair -cycles. A -cycles on is skew-symmetric if for all edges . We show that each -cycle is a sum of
two special types of skew-symmetric -cycles: skew-symmetric cycle-pair
-cycles and skew-symmetric quad -cycles. In case that the graph is
Kuratowski connected, we show that each skew-symmetric -cycle is a sum of
skew-symmetric cycle-pair -cycles. Similar results like this had previously
been obtained by one of the authors for symmetric -cycles. Symmetric
-cycles are -cycles such that for all edges
Visual semantics
Veel betekenisaspecten van taal liggen opgeslagen in het semantische geheugen. Het semantische geheugen is gebaseerd op onze ervaring met concrete objecten zoals planten, dieren en gereedschappen. Onderzoek met mensen die als gevolg van een hersenbeschadiging moeite hebben met het begrijpen van taal, heeft uitgewezen dat de betekenis van taal ook afhankelijk is van diverse sensorische en motorische gebieden van de hersenen, met name de visuele hersengebieden. Het ventrale pad is betrokken bij het herkennen van objecten, het dorsale pad maakt het mogelijk acties uit te voeren met objecten. Resultaten van experimenten die in dit proefschrift beschreven zijn geven aan dat het semantische geheugen een zeer nauwe relatie onderhoudt met het visuele systeem in onze hersenen. Dit ondersteunt ook de gedachte van een model van visuele semantiek waarin visueel-beschrijvende informatie eerst wordt opgehaald uit het lange-termijngeheugen en vervolgens wordt geactiveerd in het object-werkgeheugen. Het werkgeheugen is waarschijnlijk van belang in de koppeling tussen talige en visuele informatie. Visuele semantiek ligt dus eigenlijk op het kruispunt van semantische, visuele en talige processen
Bron:Taaluniversum
Batch Reinforcement Learning on the Industrial Benchmark: First Experiences
The Particle Swarm Optimization Policy (PSO-P) has been recently introduced
and proven to produce remarkable results on interacting with academic
reinforcement learning benchmarks in an off-policy, batch-based setting. To
further investigate the properties and feasibility on real-world applications,
this paper investigates PSO-P on the so-called Industrial Benchmark (IB), a
novel reinforcement learning (RL) benchmark that aims at being realistic by
including a variety of aspects found in industrial applications, like
continuous state and action spaces, a high dimensional, partially observable
state space, delayed effects, and complex stochasticity. The experimental
results of PSO-P on IB are compared to results of closed-form control policies
derived from the model-based Recurrent Control Neural Network (RCNN) and the
model-free Neural Fitted Q-Iteration (NFQ). Experiments show that PSO-P is not
only of interest for academic benchmarks, but also for real-world industrial
applications, since it also yielded the best performing policy in our IB
setting. Compared to other well established RL techniques, PSO-P produced
outstanding results in performance and robustness, requiring only a relatively
low amount of effort in finding adequate parameters or making complex design
decisions
State anxiety alters the neural oscillatory correlates of predictions and prediction errors during reward-based learning
Anxiety influences how the brain estimates and responds to uncertainty. The consequences of these processes on behaviour have been described in theoretical and empirical studies, yet the associated neural correlates remain unclear. Rhythm-based accounts of Bayesian predictive coding propose that predictions in generative models of perception are represented in alpha (8–12 Hz) and beta oscillations (13–30 Hz). Updates to predictions are driven by prediction errors weighted by precision (inverse variance), and are encoded in gamma oscillations (>30 Hz) and associated with suppression of beta activity. We tested whether state anxiety alters the neural oscillatory activity associated with predictions and precision-weighted prediction errors (pwPE) during learning. Healthy human participants performed a probabilistic reward-based learning task in a volatile environment. In our previous work, we described learning behaviour in this task using a hierarchical Bayesian model, revealing more precise (biased) beliefs about the tendency of the reward contingency in state anxiety, consistent with reduced learning in this group. The model provided trajectories of predictions and pwPEs for the current study, allowing us to assess their parametric effects on the time-frequency representations of EEG data. Using convolution modelling for oscillatory responses, we found that, relative to a control group, state anxiety increased beta activity in frontal and sensorimotor regions during processing of pwPE, and in fronto-parietal regions during encoding of predictions. No effects of state anxiety on gamma modulation were found. Our findings expand prior evidence on the oscillatory representations of predictions and pwPEs into the reward-based learning domain. The results suggest that state anxiety modulates beta-band oscillatory correlates of pwPE and predictions in generative models, providing insights into the neural processes associated with biased belief updating and poorer learning
A Benchmark Environment Motivated by Industrial Control Problems
In the research area of reinforcement learning (RL), frequently novel and
promising methods are developed and introduced to the RL community. However,
although many researchers are keen to apply their methods on real-world
problems, implementing such methods in real industry environments often is a
frustrating and tedious process. Generally, academic research groups have only
limited access to real industrial data and applications. For this reason, new
methods are usually developed, evaluated and compared by using artificial
software benchmarks. On one hand, these benchmarks are designed to provide
interpretable RL training scenarios and detailed insight into the learning
process of the method on hand. On the other hand, they usually do not share
much similarity with industrial real-world applications. For this reason we
used our industry experience to design a benchmark which bridges the gap
between freely available, documented, and motivated artificial benchmarks and
properties of real industrial problems. The resulting industrial benchmark (IB)
has been made publicly available to the RL community by publishing its Java and
Python code, including an OpenAI Gym wrapper, on Github. In this paper we
motivate and describe in detail the IB's dynamics and identify prototypic
experimental settings that capture common situations in real-world industry
control problems
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