OpenRaiser/Intern-Atlas huggingface dataset:
Diffusion runs low on persistence fast
Authors: Chao Chen 0012, Herbert Edelsbrunner
Venue: Conference ICCV 2011
Year: 2011

Interpreting an image as a function on a compact subset of the Euclidean plane, we get its scale-space by diffusion, spreading the image over the entire plane. This generates a 1-parameter family of functions alternatively defined as convolutions with a progressively wider Gaussian kernel. We prove that the corresponding 1-parameter family of persistence diagrams have norms that go rapidly to zero as time goes to infinity. This result rationalizes experimental observations about scale-space. We hope this will lead to targeted improvements of related computer vision methods.
Learning rotation-aware features: From invariant priors to equivariant descriptors
Authors: Uwe Schmidt 0001, Stefan Roth 0001
Venue: Conference CVPR 2012
Year: 2012

Identifying suitable image features is a central challenge in computer vision, ranging from representations for low-level to high-level vision. Due to the difficulty of this task, techniques for learning features directly from example data have recently gained attention. Despite significant benefits, these learned features often have many fewer of the desired invariances or equivariances than their hand-crafted counterparts. While translation in-/equivariance has been addressed, the issue of learning rotation-invariant or equivariant representations is hardly explored. In this paper we describe a general framework for incorporating invariance to linear image transformations into product models for feature learning. A particular benefit is that our approach induces transformation-aware feature learning, i.e. it yields features that have a notion with which specific image transformation they are used. We focus our study on rotation in-/equivariance and show the advantages of our approach in learning rotation-invariant image priors and in building rotation-equivariant and invariant descriptors of learned features, which result in state-of-the-art performance for rotation-invariant object detection.
Mergerucb: A method for large-scale online ranker evaluation
Authors: Masrour Zoghi, Shimon Whiteson, Maarten de Rijke
Venue: Conference WSDM 2015
Year: 2015

A key challenge in information retrieval is that of on-line ranker evaluation: determining which one of a finite set of rankers performs the best in expectation on the basis of user clicks on presented document lists. When the presented lists are constructed using interleaved comparison methods, which interleave lists proposed by two different candidate rankers, then the problem of minimizing the total regret accumulated while evaluating the rankers can be formalized as a K-armed dueling bandit problem. In the setting of web search, the number of rankers under consideration may be large. Scaling effectively in the presence of so many rankers is a key challenge not adequately addressed by existing algorithms.
Robust object pose estimation via statistical manifold modeling
Authors: Liang Mei, Jingen Liu, Alfred O. Hero III, Silvio Savarese
Venue: Conference ICCV 2011
Year: 2011

We propose a novel statistical manifold modeling approach that is capable of classifying poses of object categories from video sequences by simultaneously minimizing the intra-class variability and maximizing inter-pose distance. Following the intuition that an object part based representation and a suitable part selection process may help achieve our purpose, we formulate the part selection problem from a statistical manifold modeling perspective and treat part selection as adjusting the manifold of the object (parameterized by pose) by means of the manifold “alignment” and “expansion” operations. We show that manifold alignment and expansion are equivalent to minimizing the intra-class distance given a pose while increasing the inter-pose distance given an object instance respectively. We formulate and solve this (otherwise intractable) part selection problem as a combinatorial optimization problem using graph analysis techniques. Quantitative and qualitative experimental analysis validates our theoretical claims.
Learning nonlinear dynamic models
Authors: John Langford 0001, Ruslan Salakhutdinov, Tong Zhang 0001
Venue: Conference ICML 2009
Year: 2009

We present a novel approach for learning nonlinear dynamic models, which leads to a new set of tools capable of solving problems that are otherwise difficult. We provide theory showing this new approach is consistent for models with long range structure, and apply the approach to motion capture and high-dimensional video data, yielding results superior to standard alternatives.
Learning message-passing inference machines for structured prediction
Authors: Stéphane Ross, Daniel Munoz, Martial Hebert, J. Andrew Bagnell
Venue: Conference CVPR 2011
Year: 2011

Nearly every structured prediction problem in computer vision requires approximate inference due to large and complex dependencies among output labels. While graphical models provide a clean separation between modeling and inference, learning these models with approximate inference is not well understood. Furthermore, even if a good model is learned, predictions are often inaccurate due to approximations. In this work, instead of performing inference over a graphical model, we instead consider the inference procedure as a composition of predictors. Specifically, we focus on message-passing algorithms, such as Belief Propagation, and show how they can be viewed as procedures that sequentially predict label distributions at each node over a graph. Given labeled graphs, we can then train the sequence of predictors to output the correct labeling s. The result no longer corresponds to a graphical model but simply defines an inference procedure, with strong theoretical properties, that can be used to classify new graphs. We demonstrate the scalability and efficacy of our approach on 3D point cloud classification and 3D surface estimation from single images.
Rubik: Knowledge guided tensor factorization and completion for health data analytics
Authors: Yichen Wang, Robert Chen, Joydeep Ghosh, Joshua C. Denny, Abel N. Kho, You Chen, Bradley A. Malin, Jimeng Sun
Venue: Conference KDD 2015
Year: 2015

Computational phenotyping is the process of converting heterogeneous electronic health records (EHRs) into meaningful clinical concepts. Unsupervised phenotyping methods have the potential to leverage a vast amount of labeled EHR data for phenotype discovery. However, existing unsupervised phenotyping methods do not incorporate current medical knowledge and cannot directly handle missing, or noisy data. We propose Rubik, a constrained non-negative tensor factorization and completion method for phenotyping. Rubik incorporates 1) guidance constraints to align with existing medical knowledge, and 2) pairwise constraints for obtaining distinct, non-overlapping phenotypes. Rubik also has built-in tensor completion that can significantly alleviate the impact of noisy and missing data. We utilize the Alternating Direction Method of Multipliers (ADMM) framework to tensor factorization and completion, which can be easily scaled through parallel computing. We evaluate Rubik on two EHR datasets, one of which contains 647,118 records for 7,744 patients from an outpatient clinic, the other of which is a public dataset containing 1,018,614 CMS claims records for 472,645 patients. Our results show that Rubik can discover more meaningful and distinct phenotypes than the baselines. In particular, by using knowledge guidance constraints, Rubik can also discover sub-phenotypes for several major diseases. Rubik also runs around seven times faster than current state-of-the-art tensor methods. Finally, Rubik is scalable to large datasets containing millions of EHR records.
Diversifying restricted boltzmann machine for document modeling
Authors: Pengtao Xie, Yuntian Deng, Eric P. Xing
Venue: Conference KDD 2015
Year: 2015

Restricted Boltzmann Machine (RBM) has shown great effectiveness in document modeling. It utilizes hidden units to discover the latent topics and can learn compact semantic representations for documents which greatly facilitate document retrieval, clustering and classification. The popularity (or frequency) of topics in text corpora usually follow a power-law distribution where a few dominant topics occur very frequently while most topics (in the long-tail region) have low probabilities. Due to this imbalance, RBM tends to learn multiple redundant hidden units to best represent dominant topics and ignore those in the long-tail region, which renders the learned representations to be redundant and non-informative. To solve this problem, we propose Diversified RBM (DRBM) which diversifies the hidden units, to make them cover not only the dominant topics, but also those in the long-tail region. We define a diversity metric and use it as a regularizer to encourage the hidden units to be diverse. Since the diversity metric is hard to optimize directly, we instead optimize its lower bound and prove that maximizing the lower bound with projected gradient ascent can increase this diversity metric. Experiments on document retrieval and clustering demonstrate that with diversification, the document modeling power of DRBM can be greatly improved.
PIDGIN: ontology alignment using web text as interlingua
Authors: Derry Wijaya, Partha Pratim Talukdar, Tom M. Mitchell
Venue: Conference CIKM 2013
Year: 2013

The problem of aligning ontologies and database schemas across different knowledge bases and databases is fundamental to knowledge management problems, including the problem of integrating the disparate knowledge sources that form the semantic web's Linked Data [5].
Learning to trade off between exploration and exploitation in multiclass bandit prediction
Authors: Hamed Valizadegan, Rong Jin, Shijun Wang
Venue: Conference KDD 2011
Year: 2011

We study multi-class bandit prediction, an online learning problem where the learner only receives a partial feedback in each trial indicating whether the predicted class label is correct. The exploration vs. exploitation tradeoff strategy is a well-known technique for online learning with incomplete feedback (i.e., bandit setup). Banditron [8], a multi-class online learning algorithm for bandit setting, maximizes the run-time gain by balancing between exploration and exploitation with a fixed tradeoff parameter. The performance of Banditron can be quite sensitive to the choice of the tradeoff parameter and therefore effective algorithms to automatically tune this parameter is desirable. In this paper, we propose three learning strategies to automatically adjust the tradeoff parameter for Banditron. Our extensive empirical study with multiple real-world data sets verifies the efficacy of the proposed approach in learning the exploration vs. exploitation tradeoff parameter.
Expectation of f-measures: Tractable exact computation and some empirical observations of its properties
Authors: Kian Ming Adam Chai
Venue: Conference SIGIR 2005
Year: 2005

We derive a tractable and exact computation for the expectation of F-measures. We also demonstrate the non-convexity of this expectation, and investigate errors of approximating the expectation under different settings.
Contextual bandits in a collaborative environment
Authors: Qingyun Wu, Huazheng Wang, Quanquan Gu, Hongning Wang
Venue: Conference SIGIR 2016
Year: 2016

Contextual bandit algorithms provide principled online learning solutions to find optimal trade-offs between exploration and exploitation with companion side-information. They have been extensively used in many important practical scenarios, such as display advertising and content recommendation. A common practice estimates the unknown bandit parameters pertaining to each user independently. This unfortunately ignores dependency among users and thus leads to suboptimal solutions, especially for the applications that have strong social components.
Learning optimized MAP estimates in continuously-valued MRF models
Authors: Kegan G. G. Samuel, Marshall F. Tappen
Venue: Conference CVPR 2009
Year: 2009

We present a new approach for the discriminative training of continuous-valued Markov Random Field (MRF) model parameters. In our approach we train the MRF model by optimizing the parameters so that the minimum energy solution of the model is as similar as possible to the ground-truth. This leads to parameters which are directly optimized to increase the quality of the MAP estimates during inference. Our proposed technique allows us to develop a framework that is flexible and intuitively easy to understand and implement, which makes it an attractive alternative to learn the parameters of a continuous-valued MRF model. We demonstrate the effectiveness of our technique by applying it to the problems of image denoising and in-painting using the Field of Experts model. In our experiments, the performance of our system compares favourably to the Field of Experts model trained using contrastive divergence when applied to the denoising and in-painting tasks.
A generative perspective on mrfs in low-level vision
Authors: Uwe Schmidt 0001, Qi Gao, Stefan Roth 0001
Venue: Conference CVPR 2010
Year: 2010

Markov random fields (MRFs) are popular and generic probabilistic models of prior knowledge in low-level vision. Yet their generative properties are rarely examined, while application-specific models and non-probabilistic learning are gaining increased attention. In this paper we revisit the generative aspects of MRFs, and analyze the quality of common image priors in a fully application-neutral setting. Enabled by a general class of MRFs with flexible potentials and an efficient Gibbs sampler, we find that common models do not capture the statistics of natural images well. We show how to remedy this by exploiting the efficient sampler for learning better generative MRFs based on flexible potentials. We perform image restoration with these models by computing the Bayesian minimum mean squared error estimate (MMSE) using sampling. This addresses a number of shortcomings that have limited generative MRFs so far, and leads to substantially improved performance over maximum a-posteriori (MAP) estimation. We demonstrate that combining our learned generative models with sampling-based MMSE estimation yields excellent application results that can compete with recent discriminative methods.
Dealing with non-stationary environments using context detection
Authors: Bruno Castro da Silva, Eduardo W. Basso, Ana L. C. Bazzan, Paulo Martins Engel
Venue: Conference ICML 2006
Year: 2006

In this paper we introduce RL-CD, a method for solving reinforcement learning problems in non-stationary environments. The method is based on a mechanism for creating, updating and selecting one among several partial models of the environment. The partial models are incrementally built according to the system's capability of making predictions regarding a given sequence of observations. We propose, formalize and show the efficiency of this method both in a simple non-stationary environment and in a noisy scenario. We show that RL-CD performs better than two standard reinforcement learning algorithms and that it has advantages over methods specifically designed to cope with non-stationarity. Finally, we present known limitations of the method and future works.
Statistical change detection for multi-dimensional data
Authors: Xiuyao Song, Mingxi Wu, Christopher M. Jermaine, Sanjay Ranka
Venue: Conference KDD 2007
Year: 2007

This paper deals with detecting change of distribution in multi-dimensional data sets. We use sequential hypothesis testing methods from statistics to define a general, Monte-Carlo framework for solving this problem. We also define a specific statistical test for distributional change within the framework, that we call the density test. Our experimental results show that the density test has substantially more power than the two existing methods for multi-dimensional change detection.
Large-scale collaborative ranking in near-linear time
Authors: Liwei Wu, Cho-Jui Hsieh, James Sharpnack
Venue: Conference KDD 2017
Year: 2017

In this paper, we consider the Collaborative Ranking (CR) problem for recommendation systems. Given a set of pairwise preferences between items for each user, collaborative ranking can be used to rank un-rated items for each user, and this ranking can be naturally used for recommendation. It is observed that collaborative ranking algorithms usually achieve better performance since they directly minimize the ranking loss; however, they are rarely used in practice due to the poor scalability. All the existing CR algorithms have time complexity at least O(|Ω|r) per iteration, where r is the target rank and |Ω| is number of pairs which grows quadratically with number of ratings per user. For example, the Netflix data contains totally 20 billion rating pairs, and at this scale all the current algorithms have to work with significant subsampling, resulting in poor prediction on testing data.
A short-term intervention for long-term fairness in the labor market
Authors: Lily Hu, Yiling Chen
Venue: Conference WWW 2018
Year: 2018

The persistence of racial inequality in the U.S. labor market against a general backdrop of formal equality of opportunity is a troubling phenomenon that has significant ramifications on the design of hiring policies. In this paper, we show that current group disparate outcomes may be immovable even when hiring decisions are bound by an input-output notion of "individual fairness." Instead, we construct a dynamic reputational model of the labor market that illustrates the reinforcing nature of asymmetric outcomes resulting from groups» divergent accesses to resources and as a result, investment choices. To address these disparities, we adopt a dual labor market composed of a Temporary Labor Market (TLM), in which firms» hiring strategies are constrained to ensure statistical parity of workers granted entry into the pipeline, and a Permanent Labor Market (PLM), in which firms hire top performers as desired. Individual worker reputations produce externalities for their group; the corresponding feedback loop raises the collective reputation of the initially disadvantaged group via a TLM fairness intervention that need not be permanent. We show that such a restriction on hiring practices induces an equilibrium that, under particular market conditions, Pareto-dominates those arising from strategies that statistically discriminate or employ a "group-blind" criterion. The enduring nature of equilibria that are both inequitable and Pareto suboptimal suggests that fairness interventions beyond procedural checks of hiring decisions will be of critical importance in a world where machines play a greater role in the employment process.
Computational drug repositioning using continuous self-controlled case series
Authors: Zhaobin Kuang, James A. Thomson, Michael Caldwell, Peggy L. Peissig, Ron M. Stewart, David Page
Venue: Conference KDD 2016
Year: 2016

Computational Drug Repositioning (CDR) is the task of discovering potential new indications for existing drugs by mining large-scale heterogeneous drug-related data sources. Leveraging the patient-level temporal ordering information between numeric physiological measurements and various drug prescriptions provided in Electronic Health Records (EHRs), we propose a Continuous Self-controlled Case Series (CSCCS) model for CDR. As an initial evaluation, we look for drugs that can control Fasting Blood Glucose (FBG) level in our experiments. Applying CSCCS to the Marshfield Clinic EHR, well-known drugs that are indicated for controlling blood glucose level are rediscovered. Furthermore, some drugs with recent literature support for the potential effect of blood glucose level control are also identified.
Pharmacovigilance via baseline regularization with large-scale longitudinal observational data
Authors: Zhaobin Kuang, Peggy L. Peissig, Vítor Santos Costa, Richard Maclin, David Page
Venue: Conference KDD 2017
Year: 2017

Several prominent public health hazards [29] that occurred at the beginning of this century due to adverse drug events (ADEs) have raised international awareness of governments and industries about pharmacovigilance (PhV) [6,7], the science and activities to monitor and prevent adverse events caused by pharmaceutical products after they are introduced to the market. A major data source for PhV is large-scale longitudinal observational databases (LODs) [6] such as electronic health records (EHRs) and medical insurance claim databases. Inspired by the Self-Controlled Case Series (SCCS) model [27], arguably the leading method for ADE discovery from LODs, we propose baseline regularization, a regularized generalized linear model that leverages the diverse health profiles available in LODs across different <i>individuals</i> at different <i>times</i>. We apply the proposed method as well as SCCS to the Marshfield Clinic EHR. Experimental results suggest that the proposed method outperforms SCCS under various settings in identifying <i>benchmark</i> ADEs from the Observational Medical Outcomes Partnership ground truth [26].
Trust-pcl: An off-policy trust region method for continuous control
Authors: Ofir Nachum, Mohammad Norouzi 0002, Kelvin Xu, Dale Schuurmans
Venue: Conference ICLR 2018
Year: 2018

Trust region methods, such as TRPO, are often used to stabilize policy optimization algorithms in reinforcement learning (RL). While current trust region strategies are effective for continuous control, they typically require a prohibitively large amount of on-policy interaction with the environment. To address this problem, we propose an off-policy trust region method, Trust-PCL. The algorithm is the result of observing that the optimal policy and state values of a maximum reward objective with a relative-entropy regularizer satisfy a set of multi-step pathwise consistencies along any path. Thus, Trust-PCL is able to maintain optimization stability while exploiting off-policy data to improve sample efficiency. When evaluated on a number of continuous control tasks, Trust-PCL improves the solution quality and sample efficiency of TRPO.
Streaming feature selection using alpha-investing
Authors: Jing Zhou, Dean P. Foster, Robert A. Stine, Lyle H. Ungar
Venue: Conference KDD 2005
Year: 2005

In Streaming Feature Selection (SFS), new features are sequentially considered for addition to a predictive model. When the space of potential features is large, SFS offers many advantages over traditional feature selection methods, which assume that all features are known in advance. Features can be generated dynamically, focusing the search for new features on promising subspaces, and overfitting can be controlled by dynamically adjusting the threshold for adding features to the model. We describe α-investing, an adaptive complexity penalty method for SFS which dynamically adjusts the threshold on the error reduction required for adding a new feature. α-investing gives false discovery rate-style guarantees against overfitting. It differs from standard penalty methods such as AIC, BIC or RIC, which always drastically over- or under-fit in the limit of infinite numbers of non-predictive features. Empirical results show that SFS is competitive with much more compute-intensive feature selection methods such as stepwise regression, and allows feature selection on problems with over a million potential features.