VLDB 2026 Research / reviewers in the wild / expert
Nir Ailon
dblp:86/6327
· DBLP profile ↗
56ranked-venue papers
49as first author
3since 2021 · last 2025
—ORCID · none
Domains — the database's venue-derived domains; a paper can count in several
Theory of computation · 32 · 29 first-author · 1 since 2021Artificial intelligence and machine learning · 18 · 15 first-author · 2 since 2021Databases, data management, data science and information retrieval · 4 · 3 first-author · 1 since 2021Graphics, computer vision, multimedia, augmented reality and games · 3 · 2 first-authorApplied, interdisciplinary, general and emerging computing · 2 · 2 first-author
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2025 | Puzzle: Distillation-Based NAS for Inference-Optimized LLMsabstractLarge language models (LLMs) offer remarkable capabilities, yet their high inference costs restrict wider adoption.
While increasing parameter counts improves accuracy, it also broadens the gap between state-of-the-art capabilities and practical deployability. We present **Puzzle**, a hardware-aware framework that accelerates the inference of LLMs while preserving their capabilities.
Using neural architecture search (NAS) at a large-scale, Puzzle optimizes models with tens of billions of parameters.
Our approach utilizes blockwise local knowledge distillation (BLD) for parallel architecture exploration and employs mixed-integer programming for precise constraint optimization.
We showcase our framework’s impact via Llama-3.1-Nemotron-51B-Instruct (Nemotron-51B) and Llama-3.3-Nemotron-49B, two publicly available models derived from Llama-70B-Instruct. Both models achieve a 2.17x inference throughput speedup, fitting on a single NVIDIA H100 GPU while retaining 98.4% of the original model's benchmark accuracies.
These are the most accurate models supporting single H100 GPU inference with large batch sizes, despite training on 45B tokens at most, far fewer than the 15T used to train Llama-70B.
Lastly, we show that lightweight alignment on these derived models allows them to surpass the parent model in specific capabilities.
Our work establishes that powerful LLM models can be optimized for efficient deployment with only negligible loss in quality, underscoring that inference performance, not parameter count alone, should guide model selection. Akhiad Bercovich, Tomer Ronen, Talor Abramovich, Nir Ailon, Nave Assaf, Mohammad Dabbah, Ido Galil, Amnon Geifman, Yonatan Geifman, Izhak Golan, Netanel Haber, Ehud Karpas, Roi Koren, Itay Levy, Pavlo Molchanov 0001, Shahar Mor, Zach Moshe, Najeeb Nabwani, Omri Puny, Ran Rubin, Itamar Schen, Ido Shahaf, Oren Tropp, Omer Ullman Argov, Ran Zilberstein, Ran El-Yaniv |
ICML | 4 |
| 2021 | Sparse linear networks with a fixed butterfly structure: theory and practiceabstractA butterfly network consists of logarithmically many layers, each with a linear number of non-zero weights (pre-specified). The fast Johnson-Lindenstrauss transform (FJLT) can be represented as a butterfly network followed by a projection onto a random subset of the coordinates. Moreover, a random matrix based on FJLT with high probability approximates the action of any matrix on a vector. Motivated by these facts, we propose to replace a dense linear layer in any neural network by an architecture based on the butterfly network. The proposed architecture significantly improves upon the quadratic number of weights required in a standard dense layer to nearly linear with little compromise in expressibility of the resulting operator. In a collection of wide variety of experiments, including supervised prediction on both the NLP and vision data, we show that this not only produces results that match and at times outperform existing well-known architectures, but it also offers faster training and prediction in deployment. To understand the optimization problems posed by neural networks with a butterfly network, we also study the optimization landscape of the encoder-decoder network, where the encoder is replaced by a butterfly network followed by a dense linear layer in smaller dimension. Theoretical result presented in the paper explains why the training speed and outcome are not compromised by our proposed approach. Nir Ailon, Omer Leibovitch, Vineet Nair |
UAI | 1 |
| 2021 | The complexity of computing (almost) orthogonal matrices with ε-copies of the Fourier transformabstractThe complexity of computing the Fourier transform is a longstanding open problem. Very recently, Ailon (2013, 2014, 2015) showed in a collection of papers that, roughly speaking, a speedup of the Fourier transform computation implies numerical ill-condition. The papers also quantify this tradeoff. The main method for proving these results is via a potential function called quasi-entropy, reminiscent of Shannon entropy. The quasi-entropy method opens new doors to understanding the computational complexity of the important Fourier transformation. However, it suffers from various obvious limitations. This paper is motivated by one such limitation, related to the computation of near-orthogonal matrices that have the Fourier transform ‘hidden’ in low-order bits. While partly overcoming this limitation, the paper sheds light on new interesting, open problems on the intersection of computational complexity and group theory. The paper also explains why this research direction, if fruitful, has a chance of solving much bigger questions about the complexity of the Fourier transform. Nir Ailon, Gal Yehuda |
Inf. Process. Lett. | 1 |
| 2020 | Paraunitary matrices, entropy, algebraic condition number and Fourier computationabstractThe Fourier Transform is one of the most important linear transformations used in science and engineering. Cooley and Tukey's Fast Fourier Transform (FFT) from 1964 is a method for computing this transformation in time O(nlogn). From a lower bound perspective, relatively little is known. Ailon shows in 2013 an Ω(nlogn) bound for computing the normalized Fourier Transform assuming only unitary operations on two coordinates are allowed at each step, and no extra memory is allowed. In 2014, Ailon then improved the result to show that, in a κ-well conditioned computation, Fourier computation can be sped up by no more than O(κ). The main conjecture is that Ailon's result can be exponentially improved, in the sense that κ-well condition cannot admit ω(logκ) speedup. The main result here is that ‘algebraic’ κ-well condition cannot admit ω(κ) speedup. One equivalent definition of algebraic condition number is related to the degree of polynomials naturally arising as the computation evolves. Using the maximum modulus theorem from complex analysis, we show that algebraic condition number upper bounds standard condition number, and equals it in certain cases. Algebraic condition number is an interesting measure of numerical computation stability in its own right, and provides a novel computational lens. Moreover, based on evidence from other recent related work, we believe that the approach of algebraic condition number has a good chance of establishing an algebraic version of the main conjecture. Nir Ailon |
Theor. Comput. Sci. | 1 |
| 2018 | Approximate Clustering with Same-Cluster QueriesabstractAshtiani et al. proposed a Semi-Supervised Active Clustering framework (SSAC), where the learner is allowed to make adaptive queries to a domain expert. The queries are of the kind "do two given points belong to the same optimal cluster?", where the answers to these queries are assumed to be consistent with a unique optimal solution. There are many clustering contexts where such same cluster queries are feasible. Ashtiani et al. exhibited the power of such queries by showing that any instance of the k-means clustering problem, with additional margin assumption, can be solved efficiently if one is allowed to make O(k^2 log{k} + k log{n}) same-cluster queries. This is interesting since the k-means problem, even with the margin assumption, is NP-hard. In this paper, we extend the work of Ashtiani et al. to the approximation setting by showing that a few of such same-cluster queries enables one to get a polynomial-time (1+eps)-approximation algorithm for the k-means problem without any margin assumption on the input dataset. Again, this is interesting since the k-means problem is NP-hard to approximate within a factor (1+c) for a fixed constant 0 < c < 1. The number of same-cluster queries used by the algorithm is poly(k/eps) which is independent of the size n of the dataset. Our algorithm is based on the D^2-sampling technique, also known as the k-means++ seeding algorithm. We also give a conditional lower bound on the number of same-cluster queries showing that if the Exponential Time Hypothesis (ETH) holds, then any such efficient query algorithm needs to make Omega (k/poly log k) same-cluster queries. Our algorithm can be extended for the case where the query answers are wrong with some bounded probability. Another result we show for the k-means++ seeding is that a small modification of the k-means++ seeding within the SSAC framework converts it to a constant factor approximation algorithm instead of the well known O(log k)-approximation algorithm. Nir Ailon, Anup Bhattacharya, Ragesh Jaiswal, Amit Kumar 0001 |
ITCS | 1 |
| 2018 | Approximate Correlation Clustering Using Same-Cluster Queries
Nir Ailon, Anup Bhattacharya, Ragesh Jaiswal |
LATIN | 1 |
| 2018 | A New and Flexible Approach to the Analysis of Paired Comparison DataabstractWe consider the situation where $I$ items are ranked by paired comparisons. It is usually assumed that the probability that item $i$ is preferred over item $j$ is $p_{ij}=F(\mu_i-\mu_j)$ where $F$ is a symmetric distribution function, which we refer to as the comparison function, and $\mu_i$ and $\mu_j$ are the merits or scores of the compared items. This modelling framework, which is ubiquitous in the paired comparison literature, strongly depends on the assumption that the comparison function $F$ is known. In practice, however, this assumption is often unrealistic and may result in poor fit and erroneous inferences. This limitation has motivated us to relax the assumption that $F$ is fully known and simultaneously estimate the merits of the objects and the underlying comparison function. Our formulation yields a flexible semi-definite programming problem that we use as a refinement step for estimating the paired comparison probability matrix. We provide a detailed sensitivity analysis and, as a result, we establish the consistency of the resulting estimators and provide bounds on the estimation and approximation errors. Some statistical properties of the resulting estimators as well as model selection criteria are investigated. Finally, using a large data-set of computer chess matches, we estimate the comparison function and find that the model used by the International Chess Federation does not seem to apply to computer chess. Ivo F. D. Oliveira, Nir Ailon, Ori Davidov |
J. Mach. Learn. Res. | 2 |
| 2016 | Bandit online optimization over the permutahedron
Nir Ailon, Kohei Hatano, Eiji Takimoto |
Theor. Comput. Sci. | 1 |
| 2016 | Tight lower bound instances for k-means++ in two dimensions
Anup Bhattacharya, Ragesh Jaiswal, Nir Ailon |
Theor. Comput. Sci. | 3 |
| 2015 | Tighter Fourier Transform Lower Bounds
Nir Ailon |
ICALP (1) | 1 |
| 2015 | Iterative and active graph clustering using trace norm minimization without cluster size constraints
Nir Ailon, Yudong Chen 0001, Huan Xu 0001 |
J. Mach. Learn. Res. | 1 |
| 2014 | Improved Bounds for Online Learning Over the Permutahedron and Other Ranking PolytopesabstractConsider the following game: There is a fixed set V of n items. At each step an adversary chooses a score function s_t:V\mapsto[0,1], a learner outputs a ranking of V, and then s_t is revealed. The learner’s loss is the sum over v∈V, of s_t(v) times v’s position (0th, 1st, 2nd, ...) in the ranking. This problem captures, for example, online systems that iteratively present ranked lists of items to users, who then respond by choosing one (or more) sought items. The loss measures the users’ burden, which increases the further the sought items are from the top. It also captures a version of online rank aggregation. We present an algorithm of expected regret O(n\sqrtOPT + n^2), where OPT is the loss of the best (single) ranking in hindsight. This improves the previously best known algorithm of Suehiro et. al (2012) by saving a factor of Ω(\sqrt\log n). We also reduce the per-step running time from O(n^2) to O(n\log n). We provide matching lower bounds. Nir Ailon |
AISTATS | 1 |
| 2014 | Bandit Online Optimization over the Permutahedron
Nir Ailon, Kohei Hatano, Eiji Takimoto |
ALT | 1 |
| 2014 | Reducing Dueling Bandits to Cardinal BanditsabstractWe present algorithms for reducing the Dueling Bandits problem to the conventional (stochastic) Multi-Armed Bandits problem. The Dueling Bandits problem is an online model of learning with ordinal feedback of the form “A is preferred to B” (as opposed to cardinal feedback like “A has value 2.5”), giving it wide applicability in learning from implicit user feedback and revealed and stated preferences. In contrast to existing algorithms for the Dueling Bandits problem, our reductions – named \Doubler, \MultiSbm and \DoubleSbm – provide a generic schema for translating the extensive body of known results about conventional Multi-Armed Bandit algorithms to the Dueling Bandits setting. For \Doubler and \MultiSbm we prove regret upper bounds in both finite and infinite settings, and conjecture about the performance of \DoubleSbm which empirically outperforms the other two as well as previous algorithms in our experiments. In addition, we provide the first almost optimal regret bound in terms of second order terms, such as the differences between the values of the arms. Nir Ailon, Zohar S. Karnin, Thorsten Joachims |
ICML | 1 |
| 2014 | A Tight Lower Bound Instance for k-means++ in Constant Dimension
Anup Bhattacharya, Ragesh Jaiswal, Nir Ailon |
TAMC | 3 |
| 2014 | Fast and RIP-Optimal Transforms
Nir Ailon, Holger Rauhut |
Discret. Comput. Geom. | 1 |
| 2014 | Active learning using smooth relative regret approximations with applications
Nir Ailon, Ron Begleiter, Esther Ezra |
J. Mach. Learn. Res. | 1 |
| 2013 | Learning and Optimizing with Preferences
Nir Ailon |
ALT | 1 |
| 2013 | Breaking the Small Cluster Barrier of Graph ClusteringabstractThis paper investigates graph clustering in the planted cluster model in the presence of \em small clusters. Traditional results dictate that for an algorithm to provably correctly recover the clusters, \em all clusters must be sufficiently large (in particular, \tildeΩ(\sqrtn) where n is the number of nodes of the graph). We show that this is not really a restriction: by a more refined analysis of the trace-norm based matrix recovery approach proposed in (Jalali et al. 2011) and (Chen et al. 2012), we prove that small clusters, under certain mild assuptions, do not hinder recovery of large ones. Based on this result, we further devise an iterative algorithm to recover \em almost all clusters via a “peeling strategy”, i.e., recover large clusters first, leading to a reduced problem, and repeat this procedure. These results are extended to the \em partial observation setting, in which only a (chosen) part of the graph is observed. The peeling strategy gives rise to an active learning algorithm, in which edges adjacent to smaller clusters are queried more often as large clusters are learned (and removed). Our findings are supported by experiments. From a high level, this paper sheds novel insights on high-dimesional statistics and learning structured data, by presenting a structured matrix learning problem for which a one shot convex relaxation approach necessarily fails, but a carefully constructed sequence of convex relaxations does the job. Nir Ailon, Yudong Chen 0001, Huan Xu 0001 |
ICML (3) | 1 |
| 2013 | Threading machine generated emailabstractViewing email messages as parts of a sequence or a thread is a convenient way to quickly understand their context. Current threading techniques rely on purely syntactic methods, matching sender information, subject line, and reply/forward prefixes. As such, they are mostly limited to personal conversations. In contrast, machine-generated email, which amount, as per our experiments, to more than 60% of the overall email traffic, requires a different kind of threading that should reflect how a sequence of emails is caused by a few related user actions. For example, purchasing goods from an online store will result in a receipt or a confirmation message, which may be followed, possibly after a few days, by a shipment notification message from an express shipping service. In today's mail systems, they will not be a part of the same thread, while we believe they should. In this paper, we focus on this type of threading that we coin "causal threading". We demonstrate that, by analyzing recurring patterns over hundreds of millions of mail users, we can infer a causality relation between these two individual messages. In addition, by observing multiple causal relations over common messages, we can generate "causal threads" over a sequence of messages. The four key stages of our approach consist of: (1) identifying messages that are instances of the same email type or "template" (generated by the same machine process on the sender side) (2) building a causal graph, in which nodes correspond to email templates and edges indicate potential causal relations (3) learning a causal relation prediction function, and (4) automatically "threading" the incoming email stream. We present detailed experimental results obtained by analyzing the inboxes of 12.5 million Yahoo! Mail users, who voluntarily opted-in for such research. Supervised editorial judgments show that we can identify more than 70% (recall rate) of all "causal threads" at a precision level of 90%. In addition, for a search scenario we show that we achieve a precision close to 80% at 90% recall. We believe that supporting causal threads in email clients opens new grounds for improving both email search and browsing experiences. Nir Ailon, Zohar S. Karnin, Edo Liberty, Yoelle Maarek |
WSDM | 1 |
| 2013 | An Almost Optimal Unrestricted Fast Johnson-Lindenstrauss TransformabstractThe problems of random projections and sparse reconstruction have much in common and individually received much attention. Surprisingly, until now they progressed in parallel and remained mostly separate. Here, we employ new tools from probability in Banach spaces that were successfully used in the context of sparse reconstruction to advance on an open problem in random pojection. In particular, we generalize and use an intricate result by Rudelson and Veshynin [2008] for sparse reconstruction which uses Dudley’s theorem for bounding Gaussian processes. Our main result states that any set of N = exp( Õ ( n )) real vectors in n dimensional space can be linearly mapped to a space of dimension k = O (log N polylog( n )), while (1) preserving the pairwise distances among the vectors to within any constant distortion and (2) being able to apply the transformation in time O ( n log n ) on each vector. This improves on the best known bound N = exp( Õ ( n 1/2 )) achieved by Ailon and Liberty [2009] and N = exp( Õ ( n 1/3 )) by Ailon and Chazelle [2010]. The dependence in the distortion constant however is suboptimal, and since the publication of an early version of the work, the gap between upper and lower bounds has been considerably tightened obtained by Krahmer and Ward [2011]. For constant distortion, this settles the open question posed by these authors up to a polylog( n ) factor while considerably simplifying their constructions. Nir Ailon, Edo Liberty |
ACM Trans. Algorithms | 1 |
| 2012 | An Active Learning Algorithm for Ranking from Pairwise Preferences with an Almost Optimal Query Complexity
Nir Ailon |
J. Mach. Learn. Res. | 1 |
| 2012 | Improved Approximation Algorithms for Bipartite Correlation ClusteringabstractIn this work we study the problem of bipartite correlation clustering (BCC), a natural bipartite counterpart of the well-studied correlation clustering (CC) problem [N. Bansal, A. Blum, and S. Chawla, Machine Learning, 56 (2004), pp. 89--113], also referred to as graph editing [R. Shamir, R. Sharan, and D. Tsur, Discrete Appl. Math., 144 (2004), pp. 173--182]. Given a bipartite graph, the objective of BCC is to generate a set of vertex disjoint bicliques (clusters) that minimizes the symmetric difference to the original graph. The best-known approximation algorithm for BCC due to Amit [N. Amit, The Bicluster Graph Editing Problem, Master's Thesis, Tel Aviv University, Tel Aviv, Israel, 2004] guarantees an $11$-approximation ratio. In this paper we present two algorithms. The first is a linear program based $4$-approximation algorithm. Like the previous approximation algorithm, it requires solving a large convex problem, which becomes prohibitive even for modestly sized tasks. The second algorithm, and our main contribution, is a simple randomized combinatorial algorithm. It also achieves an expected $4$-approximation factor, and it is trivial to implement and highly scalable. The analysis extends a method developed by Ailon, Charikar, and Newman in 2008, where a randomized pivoting algorithm was analyzed for obtaining a $3$-approximation algorithm for CC. For analyzing our algorithm for BCC, considerably more sophisticated arguments are required in order to take advantage of the bipartite structure. Whether it is possible to achieve (or beat) the $4$-approximation factor using a scalable and deterministic algorithm remains an open problem. Nir Ailon, Noa Avigdor-Elgrabli, Edo Liberty, Anke van Zuylen |
SIAM J. Comput. | 1 |
| 2011 | Improved Approximation Algorithms for Bipartite Correlation Clustering
Nir Ailon, Noa Avigdor-Elgrabli, Edo Liberty, Anke van Zuylen |
ESA | 1 |
| 2011 | Active Learning Ranking from Pairwise Preferences with Almost Optimal Query ComplexityabstractGiven a set $V$ of $n$ elements we wish to linearly order them using pairwise preference labels which may be non-transitive (due to irrationality or arbitrary noise). The goal is to linearly order the elements while disagreeing with as few pairwise preference labels as possible. Our performance is measured by two parameters: The number of disagreements (loss) and the query complexity (number of pairwise preference labels). Our algorithm adaptively queries at most $O(n\poly(\log n,\eps^{-1}))$ preference labels for a regret of $\eps$ times the optimal loss. This is strictly better, and often significantly better than what non-adaptive sampling could achieve. Our main result helps settle an open problem posed by learning-to-rank (from pairwise information) theoreticians and practitioners: What is a provably correct way to sample preference labels? Nir Ailon |
NIPS | 1 |
| 2011 | An Almost Optimal Unrestricted Fast Johnson-Lindenstrauss TransformabstractThe problems of random projections and sparse reconstruction have much in common and individually received much attention. Surprisingly, until now they progressed in parallel and remained mostly separate. Here, we employ new tools from probability in Banach spaces that were successfully used in the context of sparse reconstruction to advance on an open problem in random pojection. In particular, we generalize and use an intricate result by Rudelson and Vershynin for sparse reconstruction which uses Dudley's theorem for bounding Gaussian processes. Our main result states that any set of real vectors in n dimensional space can be linearly mapped to a space of dimension k = O(log N polylog(n)), while (1) preserving the pairwise distances among the vectors to within any constant distortion and (2) being able to apply the transformation in time O(n log n) on each vector. This improves on the best known achieved by Ailon and Liberty and by Ailon and Chazelle. The dependence in the distortion constant however is believed to be suboptimal and subject to further investigation. For constant distortion, this settles the open question posed by these authors up to a polylog(n) factor while considerably simplifying their constructions. Nir Ailon, Edo Liberty |
SODA | 1 |
| 2011 | Ranking from pairs and triplets: information quality, evaluation methods and query complexityabstractObtaining judgments from human raters is a vital part in the design of search engines' evaluation. Today, a discrepancy exists between judgment acquisition from raters (training phase) and use of the responses for retrieval evaluation (evaluation phase). This discrepancy is due to the inconsistency between the representation of the information in both phases. During training, raters are requested to provide a relevance score for an individual result in the context of a query, whereas the evaluation is performed on ordered lists of search results, with the results' relative position (compared to other results) taken into account. As an alternative to the practice of learning to rank using relevance judgments for individual search results, more and more focus has recently been diverted to the theory and practice of learning from answers to combinatorial questions about sets of search results. That is, users, during training, are asked to rank small sets (typically pairs). Kira Radinsky, Nir Ailon |
WSDM | 2 |
| 2011 | Dense Fast Random Projections and Lean Walsh Transforms
Edo Liberty, Nir Ailon, Amit Singer |
Discret. Comput. Geom. | 2 |
| 2011 | Fitting Tree Metrics: Hierarchical Clustering and PhylogenyabstractGiven dissimilarity data on pairs of objects in a set, we study the problem of fitting a tree metric to this data so as to minimize additive error (i.e., some measure of the difference between the tree metric and the given data). This problem arises in constructing an M-level hierarchical clustering of objects (or an ultrametric on objects) so as to match the given dissimilarity data—a basic problem in statistics. Viewed in this way, the problem is a generalization of the correlation clustering problem (which corresponds to $M=1$). We give a very simple randomized combinatorial algorithm for the M-level hierarchical clustering problem that achieves an approximation ratio of $M+2$. This is a generalization of a previous factor 3 algorithm for correlation clustering on complete graphs. The problem of fitting tree metrics also arises in phylogeny where the objective is to learn the evolution tree by fitting a tree to dissimilarity data on taxa. The quality of the fit is measured by taking the $\ell_p$ norm of the difference between the tree metric constructed and the given data. Previous results obtained a factor 3 approximation for finding the closest tree metric under the $\ell_\infty$ norm. No nontrivial approximation for general $\ell_p$ norms was known before. We present a novel linear program formulation for this problem and obtain an $O((\log n \log \log n)^{1/p})$-approximation to the closest ultrametric under the $\ell_p$ norm using this. Our techniques are based on representing and viewing an ultrametric as a hierarchy of clusterings and may be useful in other contexts. Nir Ailon, Moses Charikar |
SIAM J. Comput. | 1 |
| 2011 | Self-Improving AlgorithmsabstractWe investigate ways in which an algorithm can improve its expected performance by fine-tuning itself automatically with respect to an unknown input distribution $\mathcal{D}$. We assume here that $\mathcal{D}$ is of product type. More precisely, suppose that we need to process a sequence $I_1,I_2,\ldots$ of inputs $I=(x_1,x_2,\ldots,x_n)$ of some fixed length n, where each $x_i$ is drawn independently from some arbitrary, unknown distribution $\mathcal{D}_i$. The goal is to design an algorithm for these inputs so that eventually the expected running time will be optimal for the input distribution $\mathcal{D}=\prod_i\mathcal{D}_i$. We give such self-improving algorithms for two problems: (i) sorting a sequence of numbers and (ii) computing the Delaunay triangulation of a planar point set. Both algorithms achieve optimal expected limiting complexity. The algorithms begin with a training phase during which they collect information about the input distribution, followed by a stationary regime in which the algorithms settle to their optimized incarnations. Nir Ailon, Bernard Chazelle, Kenneth L. Clarkson, Wolfgang Mulzer, Seshadhri Comandur |
SIAM J. Comput. | 1 |
| 2010 | Aggregation of Partial Rankings, p-Ratings and Top-m Lists
Nir Ailon |
Algorithmica | 1 |
| 2010 | Preference-based learning to rank
Nir Ailon, Mehryar Mohri |
Mach. Learn. | 1 |
| 2009 | A Simple Linear Ranking Algorithm Using Query Dependent Intercept Variables
Nir Ailon |
ECIR | 1 |
| 2009 | Correlation Clustering Revisited: The "True" Cost of Error Minimization Problems
Nir Ailon, Edo Liberty |
ICALP (1) | 1 |
| 2009 | Streaming k-means approximationabstractWe provide a clustering algorithm that approximately optimizes the k-means objective, in the one-pass streaming setting. We make no assumptions about the data, and our algorithm is very light-weight in terms of memory, and computation. This setting is applicable to unsupervised learning on massive data sets, or resource-constrained devices. The two main ingredients of our theoretical work are: a derivation of an extremely simple pseudo-approximation batch algorithm for k-means, in which the algorithm is allowed to output more than k centers (based on the recent k-means++"), and a streaming clustering algorithm in which batch clustering algorithms are performed on small inputs (fitting in memory) and combined in a hierarchical manner. Empirical evaluations on real and simulated data reveal the practical utility of our method." Nir Ailon, Ragesh Jaiswal, Claire Monteleoni |
NIPS | 1 |
| 2009 | Fast Dimension Reduction Using Rademacher Series on Dual BCH Codes
Nir Ailon, Edo Liberty |
Discret. Comput. Geom. | 1 |
| 2009 | The Fast Johnson--Lindenstrauss Transform and Approximate Nearest NeighborsabstractWe introduce a new low-distortion embedding of $\ell_2^d$ into $\ell_p^{O(\log n)}$ ($p=1,2$) called the fast Johnson–Lindenstrauss transform (FJLT). The FJLT is faster than standard random projections and just as easy to implement. It is based upon the preconditioning of a sparse projection matrix with a randomized Fourier transform. Sparse random projections are unsuitable for low-distortion embeddings. We overcome this handicap by exploiting the “Heisenberg principle” of the Fourier transform, i.e., its local-global duality. The FJLT can be used to speed up search algorithms based on low-distortion embeddings in $\ell_1$ and $\ell_2$. We consider the case of approximate nearest neighbors in $\ell_2^d$. We provide a faster algorithm using classical projections, which we then speed up further by plugging in the FJLT. We also give a faster algorithm for searching over the hypercube. Nir Ailon, Bernard Chazelle |
SIAM J. Comput. | 1 |
| 2008 | Dense Fast Random Projections and Lean Walsh Transforms
Edo Liberty, Nir Ailon, Amit Singer |
APPROX-RANDOM | 2 |
| 2008 | An Efficient Reduction of Ranking to Classification
Nir Ailon, Mehryar Mohri |
COLT | 1 |
| 2008 | Reconciling Real Scores with Binary Comparisons: A New Logistic Based Model for RankingabstractThe problem of ranking arises ubiquitously in almost every aspect of life, and in particular in Machine Learning/Information Retrieval. A statistical model for ranking predicts how humans rank subsets V of some universe U . In this work we define a statistical model for ranking that satisfies certain desirable properties. The model automatically gives rise to a logistic regression based approach to learning how to rank, for which the score and comparison based approaches are dual views. This offers a new generative approach to ranking which can be used for IR. There are two main contexts for this work. The first is the theory of econometrics and study of statistical models explaining human choice of alternatives. In this context, we will compare our model with other well known models. The second context is the problem of ranking in machine learning, usually arising in the context of information retrieval. Here, much work has been done in the discriminative setting, where different heuristics are used to define ranking risk functions. Our model is built rigorously and axiomatically based on very simple desirable properties defined locally for comparisons, and automatically implies the existence of a global score function serving as a natural model parameter which can be efficiently fitted to pairwise comparison judgment data by solving a convex optimization problem. Nir Ailon |
NIPS | 1 |
| 2008 | Fast dimension reduction using Rademacher series on dual BCH codes
Nir Ailon, Edo Liberty |
SODA | 1 |
| 2008 | Property-Preserving Data Reconstruction
Nir Ailon, Bernard Chazelle, Seshadhri Comandur |
Algorithmica | 1 |
| 2008 | Aggregating inconsistent information: Ranking and clusteringabstractWe address optimization problems in which we are given contradictory pieces of input information and the goal is to find a globally consistent solution that minimizes the extent of disagreement with the respective inputs. Specifically, the problems we address are rank aggregation, the feedback arc set problem on tournaments, and correlation and consensus clustering. We show that for all these problems (and various weighted versions of them), we can obtain improved approximation factors using essentially the same remarkably simple algorithm. Additionally, we almost settle a long-standing conjecture of Bang-Jensen and Thomassen and show that unless NP⊆BPP, there is no polynomial time algorithm for the problem of minimum feedback arc set in tournaments. Nir Ailon, Moses Charikar, Alantha Newman |
J. ACM | 1 |
| 2007 | Aggregation of partial rankings, p-ratings and top-m lists
Nir Ailon |
SODA | 1 |
| 2007 | Hardness of fully dense problems
Nir Ailon, Noga Alon |
Inf. Comput. | 1 |
| 2006 | On Clusters in Markov Chains
Nir Ailon, Steve Chien, Cynthia Dwork |
LATIN | 1 |
| 2006 | Self-improving algorithms
Nir Ailon, Bernard Chazelle, Seshadhri Comandur |
SODA | 1 |
| 2006 | Approximate nearest neighbors and the fast Johnson-Lindenstrauss transformabstractWe introduce a new low-distortion embedding of l2d into lpO(log n) (p=1,2), called the Fast-Johnson-Linden-strauss-Transform. The FJLT is faster than standard random projections and just as easy to implement. It is based upon the preconditioning of a sparse projection matrix with a randomized Fourier transform. Sparse random projections are unsuitable for low-distortion embeddings. We overcome this handicap by exploiting the "Heisenberg principle" of the Fourier transform, ie, its local-global duality. The FJLT can be used to speed up search algorithms based on low-distortion embeddings in l1 and l2. We consider the case of approximate nearest neighbors in l2d. We provide a faster algorithm using classical projections, which we then further speed up by plugging in the FJLT. We also give a faster algorithm for searching over the hypercube. Nir Ailon, Bernard Chazelle |
STOC | 1 |
| 2006 | Information theory in property testing and monotonicity testing in higher dimension
Nir Ailon, Bernard Chazelle |
Inf. Comput. | 1 |
| 2005 | Fitting tree metrics: Hierarchical clustering and PhylogenyabstractGiven dissimilarity data on pairs of objects in a set, we study the problem of fitting a tree metric to this data so as to minimize additive error (i.e. some measure of the difference between the tree metric and the given data). This problem arises in constructing an M-level hierarchical clustering of objects (or an ultrametric on objects) so as to match the given dissimilarity data - a basic problem in statistics. Viewed in this way, the problem is a generalization of the correlation clustering problem (which corresponds to M = 1). We give a very simple randomized combinatorial algorithm for the M-level hierarchical clustering problem that achieves an approximation ratio of M+2. This is a generalization of a previous factor 3 algorithm for correlation clustering on complete graphs. The problem of fitting tree metrics also arises in phylogeny where the objective is to learn the evolution tree by fitting a tree to dissimilarity data on taxa. The quality of the fit is measured by taking the l/sub p/ norm of the difference between the tree metric constructed and the given data. Previous results obtained a factor 3 approximation for finding the closest tree tree metric under the l/spl infin/ norm. No nontrivial approximation for general l/sub p/ norms was known before. We present a novel LP formulation for this problem and obtain an O((log n log log n)/sup 1/p/) approximation using this. Enroute, we obtain an O((log n log log n)/sup 1/p/) approximation for the closest ultrametric under the l/sub p/ norm. Our techniques are based on representing and viewing an ultrametric as a hierarchy of clusterings, and may be useful in other contexts. Nir Ailon, Moses Charikar |
FOCS | 1 |
| 2005 | Information Theory in Property Testing and Monotonicity Testing in Higher Dimension
Nir Ailon, Bernard Chazelle |
STACS | 1 |
| 2005 | Aggregating inconsistent information: ranking and clusteringabstractWe address optimization problems in which we are given contradictory pieces of input information and the goal is to find a globally consistent solution that minimizes the number of disagreements with the respective inputs. Specifically, the problems we address are rank aggregation, the feedback arc set problem on tournaments, and correlation and consensus clustering. We show that for all these problems (and various weighted versions of them), we can obtain improved approximation factors using essentially the same remarkably simple algorithm. Additionally, we almost settle a long-standing conjecture of Bang-Jensen and Thomassen and show that unless NP⊆BPP, there is no polynomial time algorithm for the problem of minimum feedback arc set in tournaments. Nir Ailon, Moses Charikar, Alantha Newman |
STOC | 1 |
| 2005 | Lower bounds for linear degeneracy testingabstractIn the late nineties, Erickson proved a remarkable lower bound on the decision tree complexity of one of the central problems of computational geometry: given n numbers, do any r of them add up to 0? His lower bound of Ω( n ⌈ r /2⌉ ), for any fixed r , is optimal if the polynomials at the nodes are linear and at most r -variate. We generalize his bound to s -variate polynomials for s > r . Erickson's bound decays quickly as r grows and never reaches above pseudo-polynomial: we provide an exponential improvement. Our arguments are based on three ideas: (i) a geometrization of Erickson's proof technique; (ii) the use of error-correcting codes; and (iii) a tensor product construction for permutation matrices. Nir Ailon, Bernard Chazelle |
J. ACM | 1 |
| 2004 | Estimating the Distance to a Monotone Function
Nir Ailon, Bernard Chazelle, Seshadhri Comandur |
APPROX-RANDOM | 1 |
| 2004 | Property-Preserving Data Reconstruction
Nir Ailon, Bernard Chazelle, Seshadhri Comandur |
ISAAC | 1 |
| 2004 | Lower bounds for linear degeneracy testingabstractIn the late nineties Erickson proved a remarkable lower bound on the decision tree complexity of one of the central problems of computational geometry: given n numbers, do any r of them add up to 0? His lower bound of Ω(n⌈r/2⌉), for any fixed r, is optimal if the polynomials at the nodes are linear and at most r-variate. We generalize his bound to s-variate polynomials for s>>r. Erickson's bound decays quickly as r grows and never reaches above pseudo-polynomial: we provide an exponential improvement. Our arguments are based on three ideas: (i) a geometrization of Erickson's proof technique; (ii) the use of error-correcting codes; and (iii) a tensor product construction for permutation matrices. Nir Ailon, Bernard Chazelle |
STOC | 1 |