Southern Denmark
On the Use of Bagging for Local Intrinsic Dimensionality Estimation
Péter, Kristóf, Campello, Ricardo J. G. B., Bailey, James, Houle, Michael E.
The theory of Local Intrinsic Dimensionality (LID) has become a valuable tool for characterizing local complexity within and across data manifolds, supporting a range of data mining and machine learning tasks. Accurate LID estimation requires samples drawn from small neighborhoods around each query to avoid biases from nonlocal effects and potential manifold mixing, yet limited data within such neighborhoods tends to cause high estimation variance. As a variance reduction strategy, we propose an ensemble approach that uses subbagging to preserve the local distribution of nearest neighbor (NN) distances. The main challenge is that the uniform reduction in total sample size within each subsample increases the proximity threshold for finding a fixed number k of NNs around the query. As a result, in the specific context of LID estimation, the sampling rate has an additional, complex interplay with the neighborhood size, where both combined determine the sample size as well as the locality and resolution considered for estimation. We analyze both theoretically and experimentally how the choice of the sampling rate and the k-NN size used for LID estimation, alongside the ensemble size, affects performance, enabling informed prior selection of these hyper-parameters depending on application-based preferences. Our results indicate that within broad and well-characterized regions of the hyper-parameters space, using a bagged estimator will most often significantly reduce variance as well as the mean squared error when compared to the corresponding non-bagged baseline, with controllable impact on bias. We additionally propose and evaluate different ways of combining bagging with neighborhood smoothing for substantial further improvements on LID estimation performance.
- Europe > Denmark > Southern Denmark (0.04)
- Oceania > Australia > Victoria > Melbourne (0.04)
- North America > United States > New Jersey > Essex County > Newark (0.04)
- Europe > Denmark > Southern Denmark (0.04)
- Asia > Middle East > Jordan (0.04)
- Research Report > New Finding (1.00)
- Research Report > Experimental Study (1.00)
- Information Technology > Artificial Intelligence > Machine Learning > Reinforcement Learning (1.00)
- Information Technology > Artificial Intelligence > Representation & Reasoning > Uncertainty > Bayesian Inference (0.46)
- Information Technology > Artificial Intelligence > Machine Learning > Learning Graphical Models > Directed Networks > Bayesian Learning (0.46)
- Information Technology > Artificial Intelligence > Machine Learning > Neural Networks > Deep Learning (0.45)
- North America > Canada > Alberta (0.14)
- Europe > Germany > Hesse > Darmstadt Region > Darmstadt (0.04)
- Europe > United Kingdom > England > Cambridgeshire > Cambridge (0.04)
- (2 more...)
- Information Technology > Artificial Intelligence > Representation & Reasoning (1.00)
- Information Technology > Data Science > Data Mining (0.68)
- Information Technology > Artificial Intelligence > Machine Learning > Statistical Learning (0.67)
- Information Technology > Artificial Intelligence > Machine Learning > Computational Learning Theory (0.46)
Medieval elite still received fancy burials despite disease stigma
Breakthroughs, discoveries, and DIY tips sent six days a week. Wealth confers privilege, and for many people during the Middle Ages, this privilege extended into the afterlife . The trend often mirrored their relationship with religion before their deaths, too--nobility and knights frequently ensured they sat in the front pews of services. Money is only one facet of social relations, however. Communities have long discriminated against and ostracized residents with debilitating illnesses--especially those with outward physical effects.
- Europe > Germany (0.07)
- North America > United States > South Dakota (0.06)
- Europe > Denmark > Southern Denmark (0.05)
- Europe > Germany > Baden-Württemberg > Tübingen Region > Tübingen (0.14)
- Europe > United Kingdom > England > Cambridgeshire > Cambridge (0.04)
- Europe > Germany > Baden-Württemberg > Freiburg (0.04)
- Europe > Denmark > Southern Denmark (0.04)
- Europe > Austria > Vienna (0.14)
- Europe > Denmark > Capital Region > Copenhagen (0.04)
- Europe > United Kingdom > England > Greater London > London (0.04)
- (3 more...)
Towards a pretrained deep learning estimator of the Linfoot informational correlation
Berg, Stéphanie M. van den, Halekoh, Ulrich, Möller, Sören, Jensen, Andreas Kryger, Hjelmborg, Jacob von Bornemann
We develop a supervised deep-learning approach to estimate mutual information between two continuous random variables. As labels, we use the Linfoot informational correlation, a transformation of mutual information that has many important properties. Our method is based on ground truth labels for Gaussian and Clayton copulas. We compare our method with estimators based on kernel density, k-nearest neighbours and neural estimators. We show generally lower bias and lower variance. As a proof of principle, future research could look into training the model with a more diverse set of examples from other copulas for which ground truth labels are available.
- North America > United States > New York (0.04)
- Europe > Denmark > Southern Denmark (0.04)
- Europe > Denmark > Capital Region > Copenhagen (0.04)
- Europe > Belgium > Flanders > Flemish Brabant > Leuven (0.04)
Who built Scandinavia's oldest wooden plank boat? An ancient fingerprint offers clues.
Science Archaeology Who built Scandinavia's oldest wooden plank boat? An ancient fingerprint offers clues. Archeologists are closer to solving the Hjortspring Boat's mysteries. Breakthroughs, discoveries, and DIY tips sent every weekday. Archaeologists examining an ancient boat discovered in Denmark over a century ago are getting some help from a clue usually associated with crime scenes .
- Europe > Sweden (0.72)
- Europe > Norway (0.72)
- Europe > Northern Europe (0.06)
- (3 more...)
Robust Adaptive Time-Varying Control Barrier Function with Application to Robotic Surface Treatment
Kim, Yitaek, Sloth, Christoffer
Set invariance techniques such as control barrier functions (CBFs) can be used to enforce time-varying constraints such as keeping a safe distance from dynamic objects. However, existing methods for enforcing time-varying constraints often overlook model uncertainties. To address this issue, this paper proposes a CBFs-based robust adaptive controller design endowing time-varying constraints while considering parametric uncertainty and additive disturbances. To this end, we first leverage Robust adaptive Control Barrier Functions (RaCBFs) to handle model uncertainty, along with the concept of Input-to-State Safety (ISSf) to ensure robustness towards input disturbances. Furthermore, to alleviate the inherent conservatism in robustness, we also incorporate a set membership identification scheme. We demonstrate the proposed method on robotic surface treatment that requires time-varying force bounds to ensure uniform quality, in numerical simulation and real robotic setup, showing that the quality is formally guaranteed within an acceptable range.
Tac2Motion: Contact-Aware Reinforcement Learning with Tactile Feedback for Robotic Hand Manipulation
Kim, Yitaek, Rask, Casper Hewson, Sloth, Christoffer
This paper proposes Tac2Motion, a contact-aware reinforcement learning framework to facilitate the learning of contact-rich in-hand manipulation tasks, such as removing a lid. To this end, we propose tactile sensing-based reward shaping and incorporate the sensing into the observation space through embedding. The designed rewards encourage an agent to ensure firm grasping and smooth finger gaiting at the same time, leading to higher data efficiency and robust performance compared to the baseline. We verify the proposed framework on the opening a lid scenario, showing generalization of the trained policy into a couple of object types and various dynamics such as torsional friction. Lastly, the learned policy is demonstrated on the multi-fingered robot, Shadow Robot, showing that the control policy can be transferred to the real world. The video is available: https://youtu.be/poeJBPR7urQ.