Search Results for author: Mehrdad Ghadiri

Found 13 papers, 3 papers with code

Approximately Optimal Core Shapes for Tensor Decompositions

no code implementations8 Feb 2023 Mehrdad Ghadiri, Matthew Fahrbach, Gang Fu, Vahab Mirrokni

This work studies the combinatorial optimization problem of finding an optimal core tensor shape, also called multilinear rank, for a size-constrained Tucker decomposition.

Combinatorial Optimization

Subquadratic Kronecker Regression with Applications to Tensor Decomposition

1 code implementation11 Sep 2022 Matthew Fahrbach, Thomas Fu, Mehrdad Ghadiri

By extending our approach to block-design matrices where one block is a Kronecker product, we also achieve subquadratic-time algorithms for (1) Kronecker ridge regression and (2) updating the factor matrices of a Tucker decomposition in ALS, which is not a pure Kronecker regression problem, thereby improving the running time of all steps of Tucker ALS.

regression Tensor Decomposition

Constant-Factor Approximation Algorithms for Socially Fair $k$-Clustering

no code implementations22 Jun 2022 Mehrdad Ghadiri, Mohit Singh, Santosh S. Vempala

We study approximation algorithms for the socially fair $(\ell_p, k)$-clustering problem with $m$ groups, whose special cases include the socially fair $k$-median ($p=1$) and socially fair $k$-means ($p=2$) problems.

Clustering

Fast Low-Rank Tensor Decomposition by Ridge Leverage Score Sampling

no code implementations22 Jul 2021 Matthew Fahrbach, Mehrdad Ghadiri, Thomas Fu

Low-rank tensor decomposition generalizes low-rank matrix approximation and is a powerful technique for discovering low-dimensional structure in high-dimensional data.

regression Tensor Decomposition

A Parameterized Family of Meta-Submodular Functions

no code implementations23 Jun 2020 Mehrdad Ghadiri, Richard Santiago, Bruce Shepherd

Submodular function maximization has found a wealth of new applications in machine learning models during the past years.

Socially Fair k-Means Clustering

2 code implementations17 Jun 2020 Mehrdad Ghadiri, Samira Samadi, Santosh Vempala

We show that the popular k-means clustering algorithm (Lloyd's heuristic), used for a variety of scientific data, can result in outcomes that are unfavorable to subgroups of data (e. g., demographic groups).

Clustering

Efficient Bayesian Inference for Nested Simulators

no code implementations pproximateinference AABI Symposium 2019 Bradley Gram-Hansen, Christian Schroeder de Witt, Robert Zinkov, Saeid Naderiparizi, Adam Scibior, Andreas Munk, Frank Wood, Mehrdad Ghadiri, Philip Torr, Yee Whye Teh, Atilim Gunes Baydin, Tom Rainforth

We introduce two approaches for conducting efficient Bayesian inference in stochastic simulators containing nested stochastic sub-procedures, i. e., internal procedures for which the density cannot be calculated directly such as rejection sampling loops.

Bayesian Inference

Beyond Submodular Maximization via One-Sided Smoothness

no code implementations19 Apr 2019 Mehrdad Ghadiri, Richard Santiago, Bruce Shepherd

Using the multilinear framework and new matroid rounding techniques for quadratic objectives, we give an $\Omega(1/\sigma^{3/2})$-approximation for maximizing a $\sigma$-semi-metric diversity function subject to matroid constraint.

Data Structures and Algorithms Computational Geometry Discrete Mathematics

Distributed Maximization of Submodular plus Diversity Functions for Multi-label Feature Selection on Huge Datasets

no code implementations20 Mar 2019 Mehrdad Ghadiri, Mark Schmidt

In this paper, we consider this problem as an optimization problem that seeks to maximize the sum of a sum-sum diversity function and a non-negative monotone submodular function.

Data Summarization feature selection +1

Active Distance-Based Clustering using K-medoids

no code implementations12 Dec 2015 Mehrdad Ghadiri, Amin Aghaee, Mahdieh Soleymani Baghshah

k-medoids algorithm is a partitional, centroid-based clustering algorithm which uses pairwise distances of data points and tries to directly decompose the dataset with $n$ points into a set of $k$ disjoint clusters.

Clustering

Max-Sum Diversification, Monotone Submodular Functions and Semi-metric Spaces

no code implementations7 Nov 2015 Sepehr Abbasi Zadeh, Mehrdad Ghadiri

In many applications such as web-based search, document summarization, facility location and other applications, the results are preferable to be both representative and diversified subsets of documents.

Document Summarization

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