Search Results for author: Ramji Venkataramanan

Found 18 papers, 3 papers with code

Spectral Estimators for Structured Generalized Linear Models via Approximate Message Passing

no code implementations28 Aug 2023 Yihan Zhang, Hong Chang Ji, Ramji Venkataramanan, Marco Mondelli

Our main result is a precise asymptotic characterization of the performance of spectral estimators.

Mixed Regression via Approximate Message Passing

no code implementations5 Apr 2023 Nelvin Tan, Ramji Venkataramanan

For max-affine regression, we propose an algorithm that combines AMP with expectation-maximization to estimate intercepts of the model along with the signals.

Denoising regression

Statistical-Computational Tradeoffs in Mixed Sparse Linear Regression

no code implementations3 Mar 2023 Gabriel Arpino, Ramji Venkataramanan

Via a simple reduction, this provides novel rigorous evidence for the existence of a computational barrier to solving exact support recovery in sparse phase retrieval with sample complexity $n = \tilde{o}(k^2)$.

regression

Precise Asymptotics for Spectral Methods in Mixed Generalized Linear Models

no code implementations21 Nov 2022 Yihan Zhang, Marco Mondelli, Ramji Venkataramanan

In a mixed generalized linear model, the objective is to learn multiple signals from unlabeled observations: each sample comes from exactly one signal, but it is not known which one.

Retrieval

Estimation in Rotationally Invariant Generalized Linear Models via Approximate Message Passing

no code implementations8 Dec 2021 Ramji Venkataramanan, Kevin Kögler, Marco Mondelli

We consider the problem of signal estimation in generalized linear models defined via rotationally invariant design matrices.

PCA Initialization for Approximate Message Passing in Rotationally Invariant Models

no code implementations NeurIPS 2021 Marco Mondelli, Ramji Venkataramanan

However, the existing analysis of AMP requires an initialization that is both correlated with the signal and independent of the noise, which is often unrealistic in practice.

Approximate Message Passing with Spectral Initialization for Generalized Linear Models

no code implementations7 Oct 2020 Marco Mondelli, Ramji Venkataramanan

We consider the problem of estimating a signal from measurements obtained via a generalized linear model.

Retrieval

Optimal Combination of Linear and Spectral Estimators for Generalized Linear Models

no code implementations7 Aug 2020 Marco Mondelli, Christos Thrampoulidis, Ramji Venkataramanan

This allows us to compute the Bayes-optimal combination of $\hat{\boldsymbol x}^{\rm L}$ and $\hat{\boldsymbol x}^{\rm s}$, given the limiting distribution of the signal $\boldsymbol x$.

Estimation of Low-Rank Matrices via Approximate Message Passing

1 code implementation6 Nov 2017 Andrea Montanari, Ramji Venkataramanan

In this paper we present a practical algorithm that can achieve Bayes-optimal accuracy above the spectral threshold.

Community Detection

Empirical Bayes Estimators for High-Dimensional Sparse Vectors

no code implementations28 Jul 2017 Pavan Srinath, Ramji Venkataramanan

An empirical Bayes shrinkage estimator, derived using a Bernoulli-Gaussian prior, is analyzed and compared with the well-known soft-thresholding estimator.

Vocal Bursts Intensity Prediction

A strong converse bound for multiple hypothesis testing, with applications to high-dimensional estimation

no code implementations14 Jun 2017 Ramji Venkataramanan, Oliver Johnson

In statistical inference problems, we wish to obtain lower bounds on the minimax risk, that is to bound the performance of any possible estimator.

Active Learning Density Estimation +1

Multilayer Codes for Synchronization from Deletions

1 code implementation18 May 2017 Mahed Abroshan, Ramji Venkataramanan, Albert Guillen i Fabregas

Consider two remote nodes, each having a binary sequence.

Information Theory Information Theory

Finite Sample Analysis of Approximate Message Passing Algorithms

no code implementations6 Jun 2016 Cynthia Rush, Ramji Venkataramanan

The concentration inequality also indicates that the number of AMP iterations $t$ can grow no faster than order $\frac{\log n}{\log \log n}$ for the performance to be close to the state evolution predictions with high probability.

Cluster-Seeking James-Stein Estimators

no code implementations1 Feb 2016 K. Pavan Srinath, Ramji Venkataramanan

The JS-estimator shrinks the observed vector towards the origin, and the risk reduction over the ML-estimator is greatest for $\boldsymbol{\theta}$ that lie close to the origin.

Capacity-achieving Sparse Superposition Codes via Approximate Message Passing Decoding

no code implementations23 Jan 2015 Cynthia Rush, Adam Greig, Ramji Venkataramanan

Sparse superposition codes were recently introduced by Barron and Joseph for reliable communication over the AWGN channel at rates approaching the channel capacity.

Decoder

Lossy Compression via Sparse Linear Regression: Computationally Efficient Encoding and Decoding

no code implementations7 Dec 2012 Ramji Venkataramanan, Tuhin Sarkar, Sekhar Tatikonda

The proposed encoding algorithm sequentially chooses columns of the design matrix to successively approximate the source sequence.

regression

Lossy Compression via Sparse Linear Regression: Performance under Minimum-distance Encoding

no code implementations3 Feb 2012 Ramji Venkataramanan, Antony Joseph, Sekhar Tatikonda

We study a new class of codes for lossy compression with the squared-error distortion criterion, designed using the statistical framework of high-dimensional linear regression.

regression

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