Search Results for author: Luca Ambrogioni

Found 30 papers, 7 papers with code

The statistical thermodynamics of generative diffusion models: Phase transitions, symmetry breaking and critical instability

no code implementations26 Oct 2023 Luca Ambrogioni

While the fundamental ideas behind these models come from non-equilibrium physics, variational inference and stochastic calculus, in this paper we show that many aspects of these models can be understood using the tools of equilibrium statistical mechanics.

Memorization Variational Inference

In search of dispersed memories: Generative diffusion models are associative memory networks

no code implementations29 Sep 2023 Luca Ambrogioni

In this work we show that generative diffusion models can be interpreted as energy-based models and that, when trained on discrete patterns, their energy function is (asymptotically) identical to that of modern Hopfield networks.

Deterministic training of generative autoencoders using invertible layers

1 code implementation19 May 2022 Gianluigi Silvestri, Daan Roos, Luca Ambrogioni

In this work, we provide a deterministic alternative to the stochastic variational training of generative autoencoders.

Denoising

Knowledge is reward: Learning optimal exploration by predictive reward cashing

no code implementations17 Sep 2021 Luca Ambrogioni

There is a strong link between the general concept of intelligence and the ability to collect and use information.

Gradient-adjusted Incremental Target Propagation Provides Effective Credit Assignment in Deep Neural Networks

no code implementations23 Feb 2021 Sander Dalm, Nasir Ahmad, Luca Ambrogioni, Marcel van Gerven

Many of the recent advances in the field of artificial intelligence have been fueled by the highly successful backpropagation of error (BP) algorithm, which efficiently solves the credit assignment problem in artificial neural networks.

Handwritten Digit Recognition

Automatic variational inference with cascading flows

no code implementations9 Feb 2021 Luca Ambrogioni, Gianluigi Silvestri, Marcel van Gerven

We evaluate the performance of the new variational programs in a series of structured inference problems.

Variational Inference

The 3TConv: An Intrinsic Approach to Explainable 3D CNNs

no code implementations1 Jan 2021 Gabrielle Ras, Luca Ambrogioni, Pim Haselager, Marcel van Gerven, Umut Güçlü

In a 3TConv the 3D convolutional filter is obtained by learning a 2D filter and a set of temporal transformation parameters, resulting in a sparse filter requiring less parameters.

Action Recognition

Explainable 3D Convolutional Neural Networks by Learning Temporal Transformations

no code implementations29 Jun 2020 Gabriëlle Ras, Luca Ambrogioni, Pim Haselager, Marcel A. J. van Gerven, Umut Güçlü

Finally, we implicitly demonstrate that, in popular ConvNets, the 2DConv can be replaced with a 3TConv and that the weights can be transferred to yield pretrained 3TConvs.

Image Classification

GAIT-prop: A biologically plausible learning rule derived from backpropagation of error

1 code implementation NeurIPS 2020 Nasir Ahmad, Marcel A. J. van Gerven, Luca Ambrogioni

An alternative called target propagation proposes to solve this implausibility by using a top-down model of neural activity to convert an error at the output of a neural network into layer-wise and plausible 'targets' for every unit.

Overcoming the Weight Transport Problem via Spike-Timing-Dependent Weight Inference

1 code implementation9 Mar 2020 Nasir Ahmad, Luca Ambrogioni, Marcel A. J. van Gerven

We propose a solution to the weight transport problem, which questions the biological plausibility of the backpropagation algorithm.

Automatic structured variational inference

2 code implementations3 Feb 2020 Luca Ambrogioni, Kate Lin, Emily Fertig, Sharad Vikram, Max Hinne, Dave Moore, Marcel van Gerven

However, the performance of the variational approach depends on the choice of an appropriate variational family.

Probabilistic Programming Variational Inference

The Indian Chefs Process

no code implementations29 Jan 2020 Patrick Dallaire, Luca Ambrogioni, Ludovic Trottier, Umut Güçlü, Max Hinne, Philippe Giguère, Brahim Chaib-Draa, Marcel van Gerven, Francois Laviolette

This paper introduces the Indian Chefs Process (ICP), a Bayesian nonparametric prior on the joint space of infinite directed acyclic graphs (DAGs) and orders that generalizes Indian Buffet Processes.

Background Hardly Matters: Understanding Personality Attribution in Deep Residual Networks

no code implementations20 Dec 2019 Gabriëlle Ras, Ron Dotsch, Luca Ambrogioni, Umut Güçlü, Marcel A. J. van Gerven

It is important that we understand the driving factors behind the predictions, in humans and in deep neural networks.

Temporal Factorization of 3D Convolutional Kernels

no code implementations9 Dec 2019 Gabriëlle Ras, Luca Ambrogioni, Umut Güçlü, Marcel A. J. van Gerven

3D convolutional neural networks are difficult to train because they are parameter-expensive and data-hungry.

Bayesian nonparametric discontinuity design

1 code implementation15 Nov 2019 Max Hinne, David Leeftink, Marcel A. J. van Gerven, Luca Ambrogioni

Quasi-experimental research designs, such as regression discontinuity and interrupted time series, allow for causal inference in the absence of a randomized controlled trial, at the cost of additional assumptions.

Causal Inference Experimental Design +3

k-GANs: Ensemble of Generative Models with Semi-Discrete Optimal Transport

no code implementations9 Jul 2019 Luca Ambrogioni, Umut Güçlü, Marcel van Gerven

A possible way of dealing with this problem is to use an ensemble of GANs, where (ideally) each network models a single mode.

Perturbative estimation of stochastic gradients

no code implementations31 Mar 2019 Luca Ambrogioni, Marcel A. J. van Gerven

Furthermore, we introduce a family of variance reduction techniques that can be applied to other gradient estimators.

Variational Inference

Wasserstein variational gradient descent: From semi-discrete optimal transport to ensemble variational inference

no code implementations7 Nov 2018 Luca Ambrogioni, Umut Guclu, Marcel van Gerven

The solution of the resulting optimal transport problem provides both a particle approximation and a set of optimal transportation densities that map each particle to a segment of the posterior distribution.

Variational Inference

Wasserstein Variational Inference

no code implementations NeurIPS 2018 Luca Ambrogioni, Umut Güçlü, Yağmur Güçlütürk, Max Hinne, Eric Maris, Marcel A. J. van Gerven

This paper introduces Wasserstein variational inference, a new form of approximate Bayesian inference based on optimal transport theory.

Bayesian Inference Variational Inference

The Kernel Mixture Network: A Nonparametric Method for Conditional Density Estimation of Continuous Random Variables

1 code implementation19 May 2017 Luca Ambrogioni, Umut Güçlü, Marcel A. J. van Gerven, Eric Maris

In the Bayesian filtering example, we show that the method can be used to filter complex nonlinear and non-Gaussian signals defined on manifolds.

Density Estimation

GP CaKe: Effective brain connectivity with causal kernels

no code implementations NeurIPS 2017 Luca Ambrogioni, Max Hinne, Marcel van Gerven, Eric Maris

Here we propose to model this causal interaction using integro-differential equations and causal kernels that allow for a rich analysis of effective connectivity.

Causal Inference

Integral Transforms from Finite Data: An Application of Gaussian Process Regression to Fourier Analysis

no code implementations10 Apr 2017 Luca Ambrogioni, Eric Maris

This is possible because the posterior expectation of Gaussian process regression maps a finite set of samples to a function defined on the whole real line, expressed as a linear combination of covariance functions.

regression

Estimating Nonlinear Dynamics with the ConvNet Smoother

no code implementations17 Feb 2017 Luca Ambrogioni, Umut Güçlü, Eric Maris, Marcel van Gerven

Estimating the state of a dynamical system from a series of noise-corrupted observations is fundamental in many areas of science and engineering.

Complex-valued Gaussian Process Regression for Time Series Analysis

no code implementations30 Nov 2016 Luca Ambrogioni, Eric Maris

Furthermore, the complex-valued Gaussian process regression allows to incorporate prior information about the structure in signal and noise and thereby to tailor the analysis to the features of the signal.

regression Time Series +1

Analysis of Nonstationary Time Series Using Locally Coupled Gaussian Processes

no code implementations31 Oct 2016 Luca Ambrogioni, Eric Maris

In this paper, we introduce a new framework for analyzing nonstationary time series using locally stationary Gaussian process analysis with parameters that are coupled through a hidden Markov model.

Gaussian Processes Time Series +1

Dynamic Decomposition of Spatiotemporal Neural Signals

no code implementations9 May 2016 Luca Ambrogioni, Marcel A. J. van Gerven, Eric Maris

Neural signals are characterized by rich temporal and spatiotemporal dynamics that reflect the organization of cortical networks.

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