OpenRaiser/Intern-Atlas huggingface dataset:
Using dependent regions for object categorization in a generative framework
Authors: Gang Wang, Ye Zhang, Li Fei-Fei 0001
Venue: Conference CVPR 2006
Year: 2006

"Bag of words" models have enjoyed much attention and achieved good performances in recent studies of object categorization. In most of these works, local patches are modeled as basic building blocks of an image, analogous to words in text documents. In most previous works using the "bag of words" models (e.g. [4, 20, 7]), the local patches are assumed to be independent with each other. In this paper, we relax the independence assumption and model explicitly the inter-dependency of the local regions. Similarly to previous work , we represent images as a collection of patches, each of which belongs to a latent "theme" that is shared across images as well as categories. We learn the theme distributions and patch distributions over the themes in a hierarchical structure [22]. In particular, we introduce a linkage structure over the latent themes to encode the dependencies of the patches. This structure enforces the semantic connections among the patches by facilitating better clustering of the themes. As a result, our models for object categories tend to be more discriminative than the ones obtained under the independent patch assumption. We show highly competitive categorization results on both the Caltech 4 and Caltech 101 object category datasets. By examining the distributions of the latent themes for each object category, we construct an object taxonomy using the 101 object classes from the Caltech 101 datasets.
Top-down color attention for object recognition
Authors: Fahad Shahbaz Khan, Joost van de Weijer 0001, María Vanrell 0001
Venue: Conference ICCV 2009
Year: 2009

Generally the bag-of-words based image representation follows a bottom-up paradigm. The subsequent stages of the process: feature detection, feature description, vocabulary construction and image representation are performed independent of the intentioned object classes to be detected. In such a framework, combining multiple cues such as shape and color often provides below-expected results.
Learning the discriminative power invariance trade off
Authors: Manik Varma, Debajyoti Ray
Venue: Conference ICCV 2007
Year: 2007

We investigate the problem of learning optimal descriptors for a given classification task. Many hand-crafted descriptors have been proposed in the literature for measuring visual similarity. Looking past initial differences, what really distinguishes one descriptor from another is the tradeoff that it achieves between discriminative power and invariance. Since this trade-off must vary from task to task, no single descriptor can be optimal in all situations. Our focus, in this paper, is on learning the optimal tradeoff for classification given a particular training set and prior constraints. The problem is posed in the kernel learning framework. We learn the optimal, domain-specific kernel as a combination of base kernels corresponding to base features which achieve different levels of trade-off (such as no invariance, rotation invariance, scale invariance, affine invariance, etc.) This leads to a convex optimisation problem with a unique global optimum which can be solved for efficiently. The method is shown to achieve state-of-the-art performance on the UIUC textures, Oxford flowers and Cal- tech 101 datasets.
On learning with dissimilarity functions
Authors: Liwei Wang 0001, Cheng Yang, Jufu Feng
Venue: Conference ICML 2007
Year: 2007

We study the problem of learning a classification task in which only a dissimilarity function of the objects is accessible. That is, data are not represented by feature vectors but in terms of their pairwise dissimilarities. We investigate the sufficient conditions for dissimilarity functions to allow building accurate classifiers. Our results have the advantages that they apply to unbounded dissimilarities and are invariant to order-preserving transformations. The theory immediately suggests a learning paradigm: construct an ensemble of decision stumps each depends on a pair of examples, then find a convex combination of them to achieve a large margin. We next develop a practical algorithm called Dissimilarity based Boosting (DBoost) for learning with dissimilarity functions under the theoretical guidance. Experimental results demonstrate that DBoost compares favorably with several existing approaches on a variety of databases and under different conditions.
Entropy of search logs: How hard is search? with personalization? with backoff?
Authors: Qiaozhu Mei, Kenneth Ward Church
Venue: Conference WSDM 2008
Year: 2008

How many pages are there on the Web? 5B? 20B? More? Less? Big bets on clusters in the clouds could be wiped out if a small cache of a few million urls could capture much of the value. Language modeling techniques are applied to MSN's search logs to estimate entropy. The perplexity is surprisingly small: millions, not billions. Entropy is a powerful tool for sizing challenges and opportunities. How hard is search? How hard are query suggestion mechanisms like auto-complete? How much does personalization help? All these difficult questions can be answered by estimation of entropy from search logs. What is the potential opportunity for personalization? In this paper, we propose a new way to personalize search, personalization with backoff. If we have relevant data for a particular user, we should use it. But if we don't, back off to larger and larger classes of similar users. As a proof of concept, we use the first few bytes of the IP address to define classes. The coefficients of each backoff class are estimated with an EM algorithm. Ideally, classes would be defined by market segments, demographics and surrogate variables such as time and geography
Propagation of trust and distrust
Authors: Ramanathan V. Guha, Ravi Kumar, Prabhakar Raghavan, Andrew Tomkins
Venue: Conference WWW 2004
Year: 2004

A (directed) network of people connected by ratings or trust scores, and a model for propagating those trust scores, is a fundamental building block in many of today's most successful e-commerce and recommendation systems. We develop a framework of trust propagation schemes, each of which may be appropriate in certain circumstances, and evaluate the schemes on a large trust network consisting of 800K trust scores expressed among 130K people. We show that a small number of expressed trusts/distrust per individual allows us to predict trust between any two people in the system with high accuracy. Our work appears to be the first to incorporate distrust in a computational trust propagation setting.
Tell me what i need to know: succinctly summarizing data with itemsets
Authors: Michael Mampaey, Nikolaj Tatti, Jilles Vreeken
Venue: Conference KDD 2011
Year: 2011

Data analysis is an inherently iterative process. That is, what we know about the data greatly determines our expectations, and hence, what result we would find the most interesting. With this in mind, we introduce a well-founded approach for succinctly summarizing data with a collection of itemsets; using a probabilistic maximum entropy model, we iteratively find the most interesting itemset, and in turn update our model of the data accordingly. As we only include itemsets that are surprising with regard to the current model, the summary is guaranteed to be both descriptive and non-redundant. The algorithm that we present can either mine the top-k most interesting itemsets, or use the Bayesian Information Criterion to automatically identify the model containing only the itemsets most important for describing the data. Or, in other words, it will 'tell you what you need to know'. Experiments on synthetic and benchmark data show that the discovered summaries are succinct, and correctly identify the key patterns in the data. The models they form attain high likelihoods, and inspection shows that they summarize the data well with increasingly specific, yet non-redundant itemsets.
Monic - modeling and monitoring cluster transitions
Authors: Myra Spiliopoulou, Irene Ntoutsi, Yannis Theodoridis, René Schult
Venue: Conference KDD 2006
Year: 2006

There is much recent work on detecting and tracking change in clusters, often based on the study of the spatiotemporal properties of a cluster. For the many applications where cluster change is relevant, among them customer relationship management, fraud detection and marketing, it is also necessary to provide insights about the nature of cluster change: Is a cluster corresponding to a group of customers simply disappearing or are its members migrating to other clusters? Is a new emerging cluster reflecting a new target group of customers or does it rather consist of existing customers whose preferences shift? To answer such questions, we propose the framework MONIC for modeling and tracking of cluster transitions. Our cluster transition model encompasses changes that involve more than one cluster, thus allowing for insights on cluster change in the whole clustering. Our transition tracking mechanism is not based on the topological properties of clusters, which are only available for some types of clustering, but on the contents of the underlying data stream. We present our first results on monitoring cluster transitions over the ACM digital library.
Spatial scan statistics: Approximations and performance study
Authors: Deepak Agarwal, Andrew McGregor, Jeff M. Phillips, Suresh Venkatasubramanian, Zhengyuan Zhu
Venue: Conference KDD 2006
Year: 2006

Spatial scan statistics are used to determine hotspots in spatial data, and are widely used in epidemiology and biosurveillance. In recent years, there has been much effort invested in designing efficient algorithms for finding such "high discrepancy" regions, with methods ranging from fast heuristics for special cases, to general grid-based methods, and to efficient approximation algorithms with provable guarantees on performance and quality.In this paper, we make a number of contributions to the computational study of spatial scan statistics. First, we describe a simple exact algorithm for finding the largest discrepancy region in a domain. Second, we propose a new approximation algorithm for a large class of discrepancy functions (including the Kulldorff scan statistic) that improves the approximation versus run time trade-off of prior methods. Third, we extend our simple exact and our approximation algorithms to data sets which lie naturally on a grid or are accumulated onto a grid. Fourth, we conduct a detailed experimental comparison of these methods with a number of known methods, demonstrating that our approximation algorithm has far superior performance in practice to prior methods, and exhibits a good performance-accuracy trade-off.All extant methods (including those in this paper) are suitable for data sets that are modestly sized; if data sets are of the order of millions of data points, none of these methods scale well. For such massive data settings, it is natural to examine whether small-space streaming algorithms might yield accurate answers. Here, we provide some negative results, showing that any streaming algorithms that even provide approximately optimal answers to the discrepancy maximization problem must use space linear in the input.
A stochastic memoizer for sequence data
Authors: Frank D. Wood, Cédric Archambeau, Jan Gasthaus, Lancelot James, Yee Whye Teh
Venue: Conference ICML 2009
Year: 2009

We propose an unbounded-depth, hierarchical, Bayesian nonparametric model for discrete sequence data. This model can be estimated from a single training sequence, yet shares statistical strength between subsequent symbol predictive distributions in such a way that predictive performance generalizes well. The model builds on a specific parameterization of an unbounded-depth hierarchical Pitman-Yor process. We introduce analytic marginalization steps (using coagulation operators) to reduce this model to one that can be represented in time and space linear in the length of the training sequence. We show how to perform inference in such a model without truncation approximation and introduce fragmentation operators necessary to do predictive inference. We demonstrate the sequence memoizer by using it as a language model, achieving state-of-the-art results.
Latent hierarchical structural learning for object detection
Authors: Long Zhu, Yuanhao Chen, Alan L. Yuille, William T. Freeman
Venue: Conference CVPR 2010
Year: 2010

We present a latent hierarchical structural learning method for object detection. An object is represented by a mixture of hierarchical tree models where the nodes represent object parts. The nodes can move spatially to allow both local and global shape deformations. The models can be trained discriminatively using latent structural SVM learning, where the latent variables are the node positions and the mixture component. But current learning methods are slow, due to the large number of parameters and latent variables, and have been restricted to hierarchies with two layers. In this paper we describe an incremental concave-convex procedure (iCCCP) which allows us to learn both two and three layer models efficiently. We show that iCCCP leads to a simple training algorithm which avoids complex multi-stage layer-wise training, careful part selection, and achieves good performance without requiring elaborate initialization. We perform object detection using our learnt models and obtain performance comparable with state-of-the-art methods when evaluated on challenging public PASCAL datasets. We demonstrate the advantages of three layer hierarchies - outperforming Felzenszwalb et al.'s two layer models on all 20 classes.
Balancing Exploration and Exploitation: Empirical Parameterization of Exploratory Search Systems
Authors: Kumaripaba Athukorala, Alan Medlar, Kalle Ilves, Dorota Glowacka
Venue: Conference CIKM 2015
Year: 2015

Exploratory searches are where a user has insufficient knowledge to define exact search criteria or does not otherwise know what they are looking for. Reinforcement learning techniques have demonstrated great potential for supporting exploratory search in information retrieval systems as they allow the system to trade-off exploration (presenting the user with alternatives topics) and exploitation (moving toward more specific topics). Users of such systems, however, often feel that the system is not responsive to user needs. This problem is not an inherent feature of such systems, but is caused by the exploration rate parameter being inappropriately tuned for a given system, dataset or user.
Measuring causal impact of online actions via natural experiments: application to display advertising
Authors: Daniel N. Hill, Robert Moakler, Alan E. Hubbard, Vadim Tsemekhman, Foster J. Provost, Kiril Tsemekhman
Venue: Conference KDD 2015
Year: 2015

Predictive models are often employed to decide actions in interactive online systems. For example, ads are selectively served to users who are modeled as being inclined to purchase the product being advertised. News feed items are populated based on a model of the user's interests. A common consequence of these predictive models is the creation of a spurious correlation, or confounding, between the action and its desired outcome. In the above examples, the targeted users are likely to buy the product or find the news item regardless of the intervention. This presents a challenge for measuring the true impact of these systems.
Semantic segmentation using regions and parts
Authors: Pablo Arbeláez, Bharath Hariharan, Chunhui Gu, Saurabh Gupta 0001, Lubomir D. Bourdev, Jitendra Malik
Venue: Conference CVPR 2012
Year: 2012

We address the problem of segmenting and recognizing objects in real world images, focusing on challenging articulated categories such as humans and other animals. For this purpose, we propose a novel design for region-based object detectors that integrates efficiently top-down information from scanning-windows part models and global appearance cues. Our detectors produce class-specific scores for bottom-up regions, and then aggregate the votes of multiple overlapping candidates through pixel classification. We evaluate our approach on the PASCAL segmentation challenge, and report competitive performance with respect to current leading techniques. On VOC2010, our method obtains the best results in 6/20 categories and the highest performance on articulated objects.
Resolving the bias in electronic medical records
Authors: Kaiping Zheng, Jinyang Gao, Kee Yuan Ngiam, Beng Chin Ooi, James Wei Luen Yip
Venue: Conference KDD 2017
Year: 2017

Electronic Medical Records (EMR) are the most fundamental resources used in healthcare data analytics. Since people visit hospital more frequently when they feel sick and doctors prescribe lab examinations when they feel necessary, we argue that there could be a strong bias in EMR observations compared with the hidden conditions of patients. Directly using such EMR for analytical tasks without considering the bias may lead to misinterpretation. To this end, we propose a general method to resolve the bias by transforming EMR to regular patient hidden condition series using a Hidden Markov Model (HMM) variant. Compared with the biased EMR series with irregular time stamps, the unbiased regular time series is much easier to be processed by most analytical models and yields better results. Extensive experimental results demonstrate that our bias resolving method imputes missing data more accurately than baselines and improves the performance of the state-of-the-art methods on typical medical data analytics.
Stock constrained recommendation in tmall
Authors: Wenliang Zhong, Rong Jin, Cheng Yang, Xiaowei Yan, Qi Zhang, Qiang Li
Venue: Conference KDD 2015
Year: 2015

A large number of recommender systems have been developed to serve users with interesting news, ads, products or other contents. One main limitation with the existing work is that they do not take into account the inventory size of of items to be recommended. As a result, popular items are likely to be out of stock soon as they have been recommended and sold to many users, significantly affecting the impact of recommendation and user experience. This observation motivates us to develop a novel aware recommender system. It jointly optimizes the recommended items for all users based on both user preference and inventory sizes of different items. It requires solving a non-smooth optimization involved estimating a matrix of nxn, where n is the number of items. With the proliferation of items, this approach can quickly become computationally infeasible. We address this challenge by developing a dual method that reduces the number of variables from n^2 to n, significantly improving the computational efficiency. We also extend this approach to the online setting, which is particularly important for big promotion events. Our empirical studies based on a real benchmark data with 100 millions of user visits from Tmall verify the effectiveness of the proposed approach.
Robust and effective metric learning using capped trace norm: Metric learning via capped trace norm
Authors: Zhouyuan Huo, Feiping Nie, Heng Huang
Venue: Conference KDD 2016
Year: 2016

Metric learning aims at automatically learning a metric from pair or triplet based constraints in data, and it can be potentially beneficial whenever the notion of metric between instances plays a nontrivial role. In Mahalanobis distance metric learning, distance matrix M is in symmetric positive semi-definite cone, and in order to avoid overfitting and to learn a better Mahalanobis distance from weakly supervised constraints, the low-rank regularization has been often imposed on matrix M to learn the correlations between features and samples. As the approximations of the rank minimization function, the trace norm and Fantope have been utilized to regularize the metric learning objectives and achieve good performance. However, these low-rank regularization models are either not tight enough to approximate rank minimization or time-consuming to tune an optimal rank. In this paper, we introduce a novel metric learning model using the capped trace norm based regularization, which uses a singular value threshold to constraint the metric matrix M as low-rank explicitly such that the rank of matrix M is stable when the large singular values vary. The capped trace norm regularization can also be viewed as the adaptive Fantope regularization. We minimize singular values which are less than threshold value and the rank of M is not necessary to be k, thus our method is more stable and applicable in practice when we do not know the optimal rank of matrix M. We derive an efficient optimization algorithm to solve the proposed new model and the algorithm convergence proof is also provided in this paper. We evaluate our method on a variety of challenging benchmarks, such as LFW and Pubfig datasets. Face verification experiments are performed and results show that our method consistently outperforms the state-of-the-art metric learning algorithms.
Optimal freshness crawl under politeness constraints
Authors: Andrey Kolobov, Yuval Peres, Eyal Lubetzky, Eric Horvitz
Venue: Conference SIGIR 2019
Year: 2019

A Web crawler is an essential part of a search engine that procures information subsequently served by the search engine to its users. As the Web is becoming increasingly more dynamic, in addition to discovering new web pages a crawler needs to keep revisiting those already in the search engine's index, in order to keep the index fresh by picking up the pages' changed content. Determining how often to recrawl pages requires making tradeoffs based on the pages' relative importance and change rates, subject to multiple resource constraints - the limited daily budget of crawl requests on the search engine's end and politeness constraints restricting the rate at which pages can be requested from a given host. In this paper, we introduce PoliteBinaryLambdaCrawl, the first optimal algorithm for freshness crawl scheduling in the presence of politeness constraints as well as non-uniform page importance scores and the crawler's own crawl request limit. We also propose an approximation for it, stating its theoretical optimality conditions and in the process discovering a connection to an approach previously thought of as a mere heuristic for freshness crawl scheduling. We explore the relative performance of PoliteBinaryLambdaCrawl and other methods for handling politeness constraints on a dataset collected by crawling over 18.5M URLs daily over 14 weeks.
Fluid motion estimation method based on physical properties of waves
Authors: Hidetomo Sakaino
Venue: Conference CVPR 2008
Year: 2008

This paper presents a fluid flow estimation method for ocean/river waves, clouds, and smoke based on the physical properties of waves. Most of the previous optical flow methods based on fluid dynamics/mechanics estimate a smooth flow using a continuity equation and/or div-curl velocity constraint. However, abrupt or inhomogeneous image motion changes in such fluid-like images are not estimated well. In this paper, we assume that many fluid-like motion changes are due to wave phenomena that lead to a brightness change. Thus, a wave generation equation is applied with a two-step optimization. A novel constraint based on the velocity-frequency relationship equation and a wave statistical property are used. The results of experiments on synthetic and real image sequences show the validity of our method.