Search Results for author: Pankaj Mehta

Found 18 papers, 6 papers with code

Les Houches Lectures on Community Ecology: From Niche Theory to Statistical Mechanics

no code implementations8 Mar 2024 Wenping Cui, Robert Marsland III, Pankaj Mehta

We then shift our focus by analyzing these same models in "high-dimensions" (i. e. in the limit where the number of species and resources in the ecosystem becomes large) and discuss how such complex ecosystems can be analyzed using methods from the statistical physics of disordered systems such as the cavity method and Random Matrix Theory.

A universal niche geometry governs the response of ecosystems to environmental perturbations

no code implementations2 Mar 2024 Akshit Goyal, Jason W. Rocks, Pankaj Mehta

How ecosystems respond to environmental perturbations is a fundamental question in ecology, made especially challenging due to the strong coupling between species and their environment.

Geometry of ecological coexistence and niche differentiation

1 code implementation21 Apr 2023 Emmy Blumenthal, Pankaj Mehta

A fundamental problem in ecology is to understand how competition shapes biodiversity and species coexistence.

Emergent competition shapes the ecological properties of multi-trophic ecosystems

no code implementations6 Mar 2023 Zhijie Feng, Robert Marsland III, Jason W. Rocks, Pankaj Mehta

Ecosystems are commonly organized into trophic levels -- organisms that occupy the same level in a food chain (e. g., plants, herbivores, carnivores).

Bias-variance decomposition of overparameterized regression with random linear features

no code implementations10 Mar 2022 Jason W. Rocks, Pankaj Mehta

We show that the linear random features model exhibits three phase transitions: two different transitions to an interpolation regime where the training error is zero, along with an additional transition between regimes with large bias and minimal bias.

regression

Cross-feeding shapes both competition and cooperation in microbial ecosystems

no code implementations11 Oct 2021 Pankaj Mehta, Robert Marsland III

Recent work suggests that cross-feeding -- the secretion and consumption of metabolic biproducts by microbes -- is essential for understanding microbial ecology.

The Geometry of Over-parameterized Regression and Adversarial Perturbations

no code implementations25 Mar 2021 Jason W. Rocks, Pankaj Mehta

Classical regression has a simple geometric description in terms of a projection of the training labels onto the column space of the design matrix.

regression

Understanding Species Abundance Distributions in Complex Ecosystems of Interacting Species

no code implementations2 Mar 2021 Jim Wu, Pankaj Mehta, David Schwab

Niche and neutral theory are two prevailing, yet much debated, ideas in ecology proposed to explain the patterns of biodiversity.

Arnol'd Tongues in Oscillator Systems with Nonuniform Spatial Driving

no code implementations23 Dec 2020 Alexander Golden, Allyson E. Sgro, Pankaj Mehta

We find that the spatial distribution of the drive signal controls the frequency ranges over which oscillators synchronize to the drive and that boundary conditions strongly influence synchronization to external drives for the CGLE.

Pattern Formation and Solitons

Memorizing without overfitting: Bias, variance, and interpolation in over-parameterized models

no code implementations26 Oct 2020 Jason W. Rocks, Pankaj Mehta

In both models, increasing the number of fit parameters leads to a phase transition where the training error goes to zero and the test error diverges as a result of the variance (while the bias remains finite).

Machine Learning as Ecology

1 code implementation2 Aug 2019 Owen Howell, Cui Wenping, Robert Marsland III, Pankaj Mehta

Machine learning methods have had spectacular success on numerous problems.

BIG-bench Machine Learning

Diverse communities behave like typical random ecosystems

1 code implementation1 Apr 2019 Wenping Cui, Robert Marsland III, Pankaj Mehta

In 1972, Robert May triggered a worldwide research program studying ecological communities using random matrix theory.

A high-bias, low-variance introduction to Machine Learning for physicists

7 code implementations23 Mar 2018 Pankaj Mehta, Marin Bukov, Ching-Hao Wang, Alexandre G. R. Day, Clint Richardson, Charles K. Fisher, David J. Schwab

The purpose of this review is to provide an introduction to the core concepts and tools of machine learning in a manner easily understood and intuitive to physicists.

BIG-bench Machine Learning Clustering +2

Comment on "Why does deep and cheap learning work so well?" [arXiv:1608.08225]

no code implementations12 Sep 2016 David J. Schwab, Pankaj Mehta

", Lin and Tegmark claim to show that the mapping between deep belief networks and the variational renormalization group derived in [arXiv:1410. 3831] is invalid, and present a "counterexample" that claims to show that this mapping does not hold.

Bayesian feature selection with strongly-regularizing priors maps to the Ising Model

no code implementations3 Nov 2014 Charles K. Fisher, Pankaj Mehta

Identifying small subsets of features that are relevant for prediction and/or classification tasks is a central problem in machine learning and statistics.

Bayesian Inference feature selection +1

An exact mapping between the Variational Renormalization Group and Deep Learning

4 code implementations14 Oct 2014 Pankaj Mehta, David J. Schwab

Here, we show that deep learning is intimately related to one of the most important and successful techniques in theoretical physics, the renormalization group (RG).

speech-recognition Speech Recognition

Fast Bayesian Feature Selection for High Dimensional Linear Regression in Genomics via the Ising Approximation

no code implementations30 Jul 2014 Charles K. Fisher, Pankaj Mehta

Feature selection, identifying a subset of variables that are relevant for predicting a response, is an important and challenging component of many methods in statistics and machine learning.

feature selection regression

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