EDBT 2026 Demo / reviewers in the wild / expert
Nemanja Djuric
dblp:35/9989
· DBLP profile ↗
20ranked-venue papers in the field
4as first author
5since 2021 · last 2025
0000-0002-6502-7891ORCID · corroborated
Domains — venue-derived; a paper can count in several
Data Mining & Knowledge Discovery · 15 (2 first)Information Retrieval & Web Search · 4 (1 first)Big Data, Cloud & Distributed Data Systems · 1 (1 first)
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2025 | AdKDD 2025abstractThe digital advertising field has always had challenging ML problems, learning from petabytes of data that is highly imbalanced, reactivity times in the milliseconds, and more recently compounded with the complex user's path to purchase across devices, across platforms, and even online/real-world behavior. The AdKDD workshop continues to be a forum for researchers in advertising, during and after KDD. Our website, which hosts slides and abstracts, continues to receive a large number of monthly visits and active users. In surveys during AdKDD 2019 and 2020, over 60% agreed that AdKDD is the reason they attended KDD, and over 90% indicated they would attend next year. The 2025 edition is particularly timely because of the increasing application of Graph-based NN and Generative AI models in advertising. Coupled with privacy-preserving initiatives, such as those enforced by GDPR or CCPA, the future of computational advertising is at an interesting crossroads. For this edition, we plan to solicit papers that span the spectrum of deep user understanding while remaining privacy-preserving. In addition, we will seek papers that discuss fairness in the context of advertising, to what extent does hyper-personalization work, and whether the ad industry as a whole needs to think through more effective business models such as incrementality. We have hosted several academic and industry luminaries as keynote speakers and have found our invited speaker series hosting expert practitioners to be an audience favorite. We will continue fielding a diverse set of keynote speakers and invited talks for this edition as well. As with past editions, we hope to motivate researchers in this space to think not only about the ML aspects but also to spark conversations about the societal impact of online advertising. Abraham Bagherjeiran, Nemanja Djuric, Kuang-chih Lee, Linsey Pang, Vladan Radosavljevic, Suju Rajan |
KDD (2) | 2 |
| 2024 | AdKDD 2024abstractThe digital advertising field has always had challenging ML problems, learning from petabytes of data that is highly imbalanced, reactivity times in the milliseconds, and more recently compounded with the complex user's path to purchase across devices, across platforms, and even online/real-world behavior. The AdKDD workshop continues to be a forum for researchers in advertising, during and after KDD. Our website which hosts slides and abstracts receives approximately 2,000 monthly visits and 1,800 active users during the KDD 2021. In surveys during AdKDD 2019 and 2020, over 60% agreed that AdKDD is the reason they attended KDD, and over 90% indicated they would attend next year. The 2024 edition is particularly timely because of the increasing application of Graph-based NN and Generative AI models in advertising. Coupled with privacy-preserving initiatives enforced by GDPR, CCPA the future of computational advertising is at an interesting crossroads. For this edition, we plan to solicit papers that span the spectrum of deep user understanding while remaining privacy-preserving. In addition, we will seek papers that discuss fairness in the context of advertising, to what extent does hyper-personalization work, and whether the ad industry as a whole needs to think through more effective business models such as incrementality. We have hosted several academic and industry luminaries as keynote speakers and have found our invited speaker series hosting expert practitioners to be an audience favorite. We will continue fielding a diverse set of keynote speakers and invited talks for this edition as well. As with past editions, we hope to motivate researchers in this space to think not only about the ML aspects but also to spark conversations about the societal impact of online advertising. Abraham Bagherjeiran, Nemanja Djuric, Kuang-chih Lee, Linsey Pang, Vladan Radosavljevic, Suju Rajan |
KDD | 2 |
| 2023 | AdKDD 2023abstractThe digital advertising field has always had challenging ML problems, learning from petabytes of data that is highly imbalanced, reactivity times in the milliseconds, and more recently compounded with the complex user's path to purchase across devices, across platforms, and even online/real-world behavior. The AdKDD workshop continues to be a forum for researchers in advertising, during and after KDD. Our website which hosts slides and abstracts receives approximately 2,000 monthly visits and 1,800 active users during the KDD 2021. In surveys during AdKDD 2019 and 2020, over 60% agreed that AdKDD is the reason they attended KDD, and over 90% indicated they would attend next year. The 2023 edition is particularly timely because of the increasing application of Graph-based NN and Generative AI models in advertising. Coupled with privacy-preserving initiatives enforced by GDPR, CCPA the future of computational advertising is at an interesting crossroads. For this edition, we plan to solicit papers that span the spectrum of deep user understanding while remaining privacy-preserving. In addition, we will seek papers that discuss fairness in the context of advertising, to what extent does hyper-personalization work, and whether the ad industry as a whole needs to think through more effective business models such as incrementality. We have hosted several academic and industry luminaries as keynote speakers and have found our invited speaker series hosting expert practitioners to be an audience favorite. We will continue fielding a diverse set of keynote speakers and invited talks for this edition as well. As with past editions, we hope to motivate researchers in this space to think not only about the ML aspects but also to spark conversations about the societal impact of online advertising. Abraham Bagherjeiran, Nemanja Djuric, Kuang-chih Lee, Linsey Pang, Vladan Radosavljevic, Suju Rajan |
KDD | 2 |
| 2022 | AdKDD 2022abstractAn average consumer spends 8+ hours a day across all devices interacting with online content almost entirely sponsored by advertisements. At over $450B global market size in 2022 and expected to pass $1T by 2027, online advertising has already surpassed traditional ads in global spend. Moreover, computational advertising in particular is perhaps the most visible and ubiquitous application of machine learning and one that interacts directly with consumers. When done right, ads help us enrich our lives and creep us out when done badly. Looking at the published literature over the last few years, many researchers might consider computational advertising as a mature field. Yet, the opposite is true. The field is evolving, however, from ads controlled by monolithic publishers and randomly rotating banner ads to highly personalized content experiences in news feeds on mobile devices and even on TV-all utilizing data amassed from petabytes of stored user data. Ads are far from done. Abraham Bagherjeiran, Nemanja Djuric, Mihajlo Grbovic, Kuang-chih Lee, Wei Liu 0007, Linsey Pang, Vladan Radosavljevic, Suju Rajan, Kexin Xie |
KDD | 2 |
| 2021 | AdKDD 2021abstractThe digital advertising field has always had challenging ML problems, learning from petabytes of data that is highly imbalanced, reactivity times in the milliseconds and more recently compounded with the complex user's path to purchase across devices, across platforms and even online/real-world behavior. The AdKDD workshop continues to be a forum for researchers in advertising, during and after KDD. Our website which hosts slides and abstracts receives approximately 2,000 monthly visits. In surveys during AdKDD 2019 and 2020, over 60% agreed that AdKDD is the reason they attended KDD and over 90% indicated they would attend next year. The 2021 edition is particularly timely because of ongoing developments in ad tracking. We will aim to discuss notions of privacy and tracking enforced by GDPR and through company policies. In addition, we will seek papers that discuss fairness in the context of advertising, to what extent does hyper-personalization work, and on whether the ad industry as a whole needs to think through more effective business models such as incrementality. Ad tech is in an interesting place of evolution/maturity now and we would like to use the AdKDD forum to get the researchers to think not only about the ML aspects but also spark conversations about the societal ones. Abraham Bagherjeiran, Nemanja Djuric, Mihajlo Grbovic, Kuang-chih Lee, Vladan Radosavljevic, Suju Rajan |
KDD | 2 |
| 2020 | Improving Movement Predictions of Traffic Actors in Bird's-Eye View Models using GANs and Differentiable Trajectory RasterizationabstractOne of the most critical pieces of the self-driving puzzle is the task of predicting future movement of surrounding traffic actors, which allows the autonomous vehicle to safely and effectively plan its future route in a complex world. Recently, a number of algorithms have been proposed to address this important problem, spurred by a growing interest of researchers from both industry and academia. Methods based on top-down scene rasterization on one side and Generative Adversarial Networks (GANs) on the other have shown to be particularly successful, obtaining state-of-the-art accuracies on the task of traffic movement prediction. In this paper we build upon these two directions and propose a raster-based conditional GAN architecture, powered by a novel differentiable rasterizer module at the input of the conditional discriminator that maps generated trajectories into the raster space in a differentiable manner. This simplifies the task for the discriminator as trajectories that are not scene-compliant are easier to discern, and allows the gradients to flow back forcing the generator to output better, more realistic trajectories. We evaluated the proposed method on a large-scale, real-world data set, showing that it outperforms state-of-the-art GAN-based baselines. Eason Wang, Henggang Cui, Sai Yalamanchi, Mohana Moorthy, Nemanja Djuric |
KDD | 5 |
| 2016 | Network-Efficient Distributed Word2vec Training System for Large VocabulariesabstractWord2vec is a popular family of algorithms for unsupervised training of dense vector representations of words on large text corpuses. The resulting vectors have been shown to capture semantic relationships among their corresponding words, and have shown promise in reducing a number of natural language processing (NLP) tasks to mathematical operations on these vectors. While heretofore applications of word2vec have centered around vocabularies with a few million words, wherein the vocabulary is the set of words for which vectors are simultaneously trained, novel applications are emerging in areas outside of NLP with vocabularies comprising several 100 million words. Existing word2vec training systems are impractical for training such large vocabularies as they either require that the vectors of all vocabulary words be stored in the memory of a single server or suffer unacceptable training latency due to massive network data transfer. In this paper, we present a novel distributed, parallel training system that enables unprecedented practical training of vectors for vocabularies with several 100 million words on a shared cluster of commodity servers, using far less network traffic than the existing solutions. We evaluate the proposed system on a benchmark data set, showing that the quality of vectors does not degrade relative to non-distributed training. Finally, for several quarters, the system has been deployed for the purpose of matching queries to ads in Gemini, the sponsored search advertising platform at Yahoo, resulting in significant improvement of business metrics. Erik Ordentlich, Lee Yang, Andy Feng, Peter Cnudde, Mihajlo Grbovic, Nemanja Djuric, Vladan Radosavljevic, Gavin Owens |
CIKM | 6 |
| 2016 | Scalable Semantic Matching of Queries to Ads in Sponsored Search AdvertisingabstractSponsored search represents a major source of revenue for web search engines. The advertising model brings a unique possibility for advertisers to target direct user intent communicated through a search query, usually done by displaying their ads alongside organic search results for queries deemed relevant to their products or services. However, due to a large number of unique queries, it is particularly challenging for advertisers to identify all relevant queries. For this reason search engines often provide a service of advanced matching, which automatically finds additional relevant queries for advertisers to bid on. We present a novel advance match approach based on the idea of semantic embeddings of queries and ads. The embeddings were learned using a large data set of user search sessions, consisting of search queries, clicked ads and search links, while utilizing contextual information such as dwell time and skipped ads. To address the large-scale nature of our problem, both in terms of data and vocabulary size, we propose a novel distributed algorithm for training of the embeddings. Finally, we present an approach for overcoming a cold-start problem associated with new ads and queries. We report results of editorial evaluation and online tests on actual search traffic. The results show that our approach significantly outperforms baselines in terms of relevance, coverage and incremental revenue. Lastly, as part of this study, we open sourced query embeddings that can be used to advance the field. Mihajlo Grbovic, Nemanja Djuric, Vladan Radosavljevic, Fabrizio Silvestri, Ricardo Baeza-Yates, Andrew Feng, Erik Ordentlich, Lee Yang, Gavin Owens |
SIGIR | 2 |
| 2016 | TargetAd2016: 2nd International Workshop on Ad Targeting at ScaleabstractThe 2nd International Workshop on Ad Targeting at Scale will be held in San Francisco, California, USA on February 22nd, 2016, co-located with the 9th ACM International Conference on Web Search and Data Mining (WSDM). The main objective of the workshop is to address the challenges of ad targeting in web-scale settings. The workshop brings together interdisciplinary researchers in computational advertising, recommender systems, personalization, and related areas, to share, exchange, learn, and develop preliminary results, new concepts, ideas, principles, and methodologies on applying data mining technologies to ad targeting. We have constructed an exciting program of eight refereed papers and several invited talks that will help us better understand the future of ad targeting. Mihajlo Grbovic, Nemanja Djuric, Vladan Radosavljevic |
WSDM | 2 |
| 2016 | Portrait of an Online Shopper: Understanding and Predicting Consumer BehaviorabstractConsumer spending accounts for a large fraction of economic footprint of modern countries. Increasingly, consumer activity is moving to the web, where digital receipts of online purchases provide valuable data sources detailing consumer behavior. We consider such data extracted from emails and combined with with consumers' demographic information, which we use to characterize, model, and predict purchasing behavior. We analyze such behavior of consumers in different age and gender groups, and find interesting, actionable patterns that can be used to improve ad targeting systems. For example, we found that the amount of money spent on online purchases grows sharply with age, peaking in the late 30s, while shoppers from wealthy areas tend to purchase more expensive items and buy them more frequently. Furthermore, we look at the influence of social connections on purchasing habits, as well as at the temporal dynamics of online shopping where we discovered daily and weekly behavioral patterns. Finally, we build a model to predict when shoppers are most likely to make a purchase and how much will they spend, showing improvement over baseline approaches. The presented results paint a clear picture of a modern online shopper, and allow better understanding of consumer behavior that can help improve marketing efforts and make shopping more pleasant and efficient experience for online customers. Farshad Kooti, Kristina Lerman, Luca Maria Aiello, Mihajlo Grbovic, Nemanja Djuric, Vladan Radosavljevic |
WSDM | 5 |
| 2015 | Gender and Interest Targeting for Sponsored Post Advertising at TumblrabstractAs one of the leading platforms for creative content, Tumblr offers advertisers a unique way of creating brand identity. Advertisers can tell their story through images, animation, text, music, video, and more, and can promote that content by sponsoring it to appear as an advertisement in the users' live feeds. In this paper, we present a framework that enabled two of the key targeted advertising components for Tumblr, gender and interest targeting. We describe the main challenges encountered during the development of the framework, which include the creation of a ground truth for training gender prediction models, as well as mapping Tumblr content to a predefined interest taxonomy. For purposes of inferring user interests, we propose a novel semi-supervised neural language model for categorization of Tumblr content (i.e., post tags and post keywords). The model was trained on a large-scale data set consisting of $6.8$ billion user posts, with a very limited amount of categorized keywords, and was shown to have superior performance over the baseline approaches. We successfully deployed gender and interest targeting capability in Yahoo production systems, delivering inference for users that covers more than 90% of daily activities on Tumblr. Online performance results indicate advantages of the proposed approach, where we observed 20% increase in user engagement with sponsored posts in comparison to untargeted campaigns. Mihajlo Grbovic, Vladan Radosavljevic, Nemanja Djuric, Narayan L. Bhamidipati, Ananth Nagarajan |
KDD | 3 |
| 2015 | E-commerce in Your Inbox: Product Recommendations at ScaleabstractIn recent years online advertising has become increasingly ubiquitous and effective. Advertisements shown to visitors fund sites and apps that publish digital content, manage social networks, and operate e-mail services. Given such large variety of internet resources, determining an appropriate type of advertising for a given platform has become critical to financial success. Native advertisements, namely ads that are similar in look and feel to content, have had great success in news and social feeds. However, to date there has not been a winning formula for ads in e-mail clients. In this paper we describe a system that leverages user purchase history determined from e-mail receipts to deliver highly personalized product ads to Yahoo Mail users. We propose to use a novel neural language-based algorithm specifically tailored for delivering effective product recommendations, which was evaluated against baselines that included showing popular products and products predicted based on co-occurrence. We conducted rigorous offline testing using a large-scale product purchase data set, covering purchases of more than 29 million users from 172 e-commerce websites. Ads in the form of product recommendations were successfully tested on online traffic, where we observed a steady 9% lift in click-through rates over other ad formats in mail, as well as comparable lift in conversion rates. Following successful tests, the system was launched into production during the holiday season of 2014. Mihajlo Grbovic, Vladan Radosavljevic, Nemanja Djuric, Narayan L. Bhamidipati, Jaikit Savla, Varun Bhagwan, Doug Sharp |
KDD | 3 |
| 2015 | Context- and Content-aware Embeddings for Query Rewriting in Sponsored SearchabstractSearch engines represent one of the most popular web services, visited by more than 85% of internet users on a daily basis. Advertisers are interested in making use of this vast business potential, as very clear intent signal communicated through the issued query allows effective targeting of users. This idea is embodied in a sponsored search model, where each advertiser maintains a list of keywords they deem indicative of increased user response rate with regards to their business. According to this targeting model, when a query is issued all advertisers with a matching keyword are entered into an auction according to the amount they bid for the query, and the winner gets to show their ad. One of the main challenges is the fact that a query may not match many keywords, resulting in lower auction value, lower ad quality, and lost revenue for advertisers and publishers. Possible solution is to expand a query into a set of related queries and use them to increase the number of matched ads, called query rewriting. To this end, we propose rewriting method based on a novel query embedding algorithm, which jointly models query content as well as its context within a search session. As a result, queries with similar content and context are mapped into vectors close in the embedding space, which allows expansion of a query via simple K-nearest neighbor search in the projected space. The method was trained on more than 12 billion sessions, one of the largest corpuses reported thus far, and evaluated on both public TREC data set and in-house sponsored search data set. The results show the proposed approach significantly outperformed existing state-of-the-art, strongly indicating its benefits and the monetization potential. Mihajlo Grbovic, Nemanja Djuric, Vladan Radosavljevic, Fabrizio Silvestri, Narayan L. Bhamidipati |
SIGIR | 2 |
| 2015 | Hierarchical Neural Language Models for Joint Representation of Streaming Documents and their ContentabstractWe consider the problem of learning distributed representations for documents in data streams. The documents are represented as low-dimensional vectors and are jointly learned with distributed vector representations of word tokens using a hierarchical framework with two embedded neural language models. In particular, we exploit the context of documents in streams and use one of the language models to model the document sequences, and the other to model word sequences within them. The models learn continuous vector representations for both word tokens and documents such that semantically similar documents and words are close in a common vector space. We discuss extensions to our model, which can be applied to personalized recommendation and social relationship mining by adding further user layers to the hierarchy, thus learning user-specific vectors to represent individual preferences. We validated the learned representations on a public movie rating data set from MovieLens, as well as on a large-scale Yahoo News data comprising three months of user activity logs collected on Yahoo servers. The results indicate that the proposed model can learn useful representations of both documents and word tokens, outperforming the current state-of-the-art by a large margin. Nemanja Djuric, Vladan Radosavljevic, Mihajlo Grbovic, Narayan L. Bhamidipati |
WWW | 1 |
| 2014 | Hidden Conditional Random Fields with Deep User Embeddings for Ad TargetingabstractEstimating a user's propensity to click on a display ad or purchase a particular item is a critical task in targeted advertising, a burgeoning online industry worth billions of dollars. Better and more accurate estimation methods result in improved online user experience, as only relevant and interesting ads are shown, and may also lead to large benefits for advertisers, as targeted users are more likely to click or make a purchase. In this paper we address this important problem, and propose an approach for improved estimation of ad click or conversion probability based on a sequence of user's online actions, modeled using Hidden Conditional Random Fields (HCRF) model. In addition, in order to address the sparsity issue at the input side of the HCRF model, we propose to learn distributed, low-dimensional representations of user actions through a directed skip-gram, a neural architecture suitable for sequential data. Experimental results on a real-world data set comprising thousands of user sessions collected at Yahoo servers clearly indicate the benefits and the potential of the proposed approach, which outperformed competing state-of-the-art algorithms and obtained significant improvements in terms of retrieval measures. Nemanja Djuric, Vladan Radosavljevic, Mihajlo Grbovic, Narayan L. Bhamidipati |
ICDM | 1 |
| 2014 | Frugal Traffic Monitoring with Autonomous Participatory SensingabstractAs mobile devices are becoming pervasive, participatory sensing is becoming an attractive way of collecting large quantities of valuable location-based data. An important participatory sensing application is traffic monitoring, where GPS-enabled smartphones can provide invaluable information about traffic conditions. In this paper we propose a strategy for frugal sensing in which the participants send only a fraction of the observed traffic information to reduce costs while achieving high accuracy. The strategy is based on autonomous sensing, in which participants make decisions to send traffic information without guidance from the central server, thus reducing the communication overhead and improving privacy. We propose to use traffic flow theory in deciding whether or not to send an observation to the server. To provide accurate and computationally efficient estimation of the current traffic, we propose to use a budgeted version of the Gaussian Process model on the server side. The model is tuned to be robust to missing observations, which occur quite often in frugal sensing. The experiments on real-life traffic data set indicate that the proposed approach can use up to two orders of magnitude less samples than a baseline approach when estimating traffic speed on a highway network, with only a negligible loss in accuracy. Vladimir Coric, Nemanja Djuric, Slobodan Vucetic |
SDM | 2 |
| 2013 | Distributed confidence-weighted classification on MapReduceabstractExplosive growth in data size, data complexity, and data rates, triggered by emergence of high-throughput technologies such as remote sensing, crowd-sourcing, social networks, or computational advertising, in recent years has led to an increasing availability of data sets of unprecedented scales, with billions of high-dimensional data examples stored on hundreds of terabytes of memory. In order to make use of this large-scale data and extract useful knowledge, researchers in machine learning and data mining communities are faced with numerous challenges, since the classification algorithms designed for standard desktop computers are not capable of addressing these problems due to memory and time constraints. As a result, there exists an evident need for development of novel, more scalable algorithms that can handle large data sets. In this paper we propose such method, named AROW-MR, a linear SVM solver for efficient training of recently proposed confidence-weighted (CW) classifiers. Linear CW models maintain a Gaussian distribution over parameter vectors, thus allowing a user to estimate, in addition to separating hyperplane between two classes, parameter confidence as well. The proposed method employs MapReduce framework to train CW classifier in a distributed way, obtaining significant improvements in both training time and accuracy. This is achieved through training of local CW classifiers on each mapper, followed by optimally combining local classifiers on the reducer to obtain aggregated, more accurate CW linear model. We validated the proposed algorithm on synthetic data, and further showed that AROW-MR algorithm outperforms the baseline classifiers on an industrial, large-scale task of Ad Latency prediction, with nearly one billion examples. Nemanja Djuric, Mihajlo Grbovic, Slobodan Vucetic |
IEEE BigData | 1 |
| 2013 | Efficient Visualization of Large-Scale Data Tables through Reordering and Entropy MinimizationabstractVisualization of data tables with n examples and m columns using heat maps provides a holistic view of the original data. As there are n! ways to order rows and m! ways to order columns, and data tables are typically ordered without regard to visual inspection, heat maps of the original data tables often appear as noisy images. However, if rows and columns of a data table are ordered such that similar rows and similar columns are grouped together, a heat map may provide a deep insight into the underlying data distribution. We propose an information-theoretic approach to produce a well-ordered data table. In particular, we search for ordering that minimizes entropy of residuals of predictive coding applied on the ordered data table. This formalization leads to a novel ordering procedure, EM-ordering, that can be applied separately on rows and columns. For ordering of rows, EM-ordering repeats until convergence the steps of (1) rescaling columns and (2) solving a Traveling Salesman Problem (TSP) where rows are treated as cities. To allow fast ordering of large data tables, we propose an efficient TSP heuristic with modest O(n log(n)) time complexity. When compared to the existing state-of-the-art reordering approaches, we show that the method often provides heat maps of higher visual quality, while being significantly more scalable. Moreover, analysis of real-world traffic and financial data sets using the proposed method, which allowed us to readily gain deeper insights about the data, further confirmed that EM-ordering can be a valuable tool for visual exploration of large-scale data sets. Nemanja Djuric, Slobodan Vucetic |
ICDM | 1 |
| 2012 | Supervised Clustering of Label Ranking DataabstractIn this paper we study supervised clustering in the context of label ranking data. Segmentation of such complex data has many potential real-world applications. For example, in target marketing, the goal is to cluster customers in the feature space by taking into consideration the assigned, potentially incomplete product preferences, such that the preferences of instances within a cluster are more similar than the preferences of customers in the other clusters. We establish several heuristic baselines for this application that make use of well-known algorithms such as K-means, and propose a principled algorithm specifically tailored for this type of clustering. It is based on the Plackett-Luce (PL) probabilistic ranking model. Each cluster is represented as a union of Voronoi cells defined by a set of prototypes and is assigned a set of PL label scores that determine the cluster-specific label ranking. The unknown cluster PL parameters and prototype positions are determined using a supervised learning technique. Cluster membership and ranking for a new instance is determined by membership of its nearest prototype. The proposed algorithms were empirically evaluated on synthetic and reallife label ranking data. The PL-based method was superior to the heuristically-based supervised clustering approaches. The proposed PL-based algorithm was also evaluated on the task of label ranking prediction. The results showed that it is highly competitive to the state of the art label ranking algorithms, and that it is particularly accurate on data with partial rankings. Mihajlo Grbovic, Nemanja Djuric, Slobodan Vucetic |
SDM | 2 |
| 2011 | Trading representability for scalability: adaptive multi-hyperplane machine for nonlinear classificationabstractSupport Vector Machines (SVMs) are among the most popular and successful classification algorithms. Kernel SVMs often reach state-of-the-art accuracies, but suffer from the curse of kernelization due to linear model growth with data size on noisy data. Linear SVMs have the ability to efficiently learn from truly large data, but they are applicable to a limited number of domains due to low representational power. To fill the representability and scalability gap between linear and nonlinear SVMs, we propose the Adaptive Multi-hyperplane Machine (AMM) algorithm that accomplishes fast training and prediction and has capability to solve nonlinear classification problems. AMM model consists of a set of hyperplanes (weights), each assigned to one of the multiple classes, and predicts based on the associated class of the weight that provides the largest prediction. The number of weights is automatically determined through an iterative algorithm based on the stochastic gradient descent algorithm which is guaranteed to converge to a local optimum. Since the generalization bound decreases with the number of weights, a weight pruning mechanism is proposed and analyzed. The experiments on several large data sets show that AMM is nearly as fast during training and prediction as the state-of-the-art linear SVM solver and that it can be orders of magnitude faster than kernel SVM. In accuracy, AMM is somewhere between linear and kernel SVMs. For example, on an OCR task with 8 million highly dimensional training examples, AMM trained in 300 seconds on a single-core processor had 0.54% error rate, which was significantly lower than 2.03% error rate of a linear SVM trained in the same time and comparable to 0.43% error rate of a kernel SVM trained in 2 days on 512 processors. The results indicate that AMM could be an attractive option when solving large-scale classification problems. The software is available at www.dabi.temple.edu/~vucetic/AMM.html. Nemanja Djuric, Koby Crammer, Slobodan Vucetic |
KDD | 2 |