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Luca Ambrogioni

20 accepted papers

2026

The Entropic Signature of Class Speciation in Diffusion Models

ICML 2026poster

Diffusion models do not recover semantic structure uniformly over time. Instead, samples transition from semantic ambiguity to class commitment within a narrow regime. Recent theoretical work attributes this transition to dynamical instabilities along class-separating directions, but practical metho…

Cited by 0SourceScholar
2025

Dynamic Negative Guidance of Diffusion Models

ICLR 2025poster

Negative Prompting (NP) is widely utilized in diffusion models, particularly in text-to-image applications, to prevent the generation of undesired features. In this paper, we show that conventional NP is limited by the assumption of a constant guidance scale, which may lead to highly suboptimal resu…

2025

Feedback Guidance of Diffusion Models

NeurIPS 2025poster

While Classifier-Free Guidance (CFG) has become standard for improving sample fidelity in conditional diffusion models, it can harm diversity and induce memorization by applying constant guidance regardless of whether a particular sample needs correction. We propose **F**eed**B**ack **G**uidance (FB…

Cited by 0SourceScholar
2025

Manifolds, Random Matrices and Spectral Gaps: The geometric phases of generative diffusion

ICLR 2025poster

In this paper, we investigate the latent geometry of generative diffusion models under the manifold hypothesis. For this purpose, we analyze the spectrum of eigenvalues (and singular values) of the Jacobian of the score function, whose discontinuities (gaps) reveal the presence and dimensionality of…

Cited by 8SourcePDFScholar
2025

VCT: Training Consistency Models with Variational Noise Coupling

ICML 2025poster

Consistency Training (CT) has recently emerged as a strong alternative to diffusion models for image generation. However, non-distillation CT often suffers from high variance and instability, motivating ongoing research into its training dynamics. We propose Variational Consistency Training (VCT), a…

2023

Deterministic training of generative autoencoders using invertible layers

ICLR 2023top-25%

In this work, we provide a deterministic alternative to the stochastic variational training of generative autoencoders. We refer to these new generative autoencoders as AutoEncoders within Flows (AEF), since the encoder and decoder are defined as affine layers of an overall invertible architecture.…

2022

Embedded-model flows: Combining the inductive biases of model-free deep learning and explicit probabilistic modeling

ICLR 2022poster

Normalizing flows have shown great success as general-purpose density estimators. However, many real world applications require the use of domain-specific knowledge, which normalizing flows cannot readily incorporate. We propose embedded-model flows (EMF), which alternate general-purpose transformat…

2021

Automatic structured variational inference

AISTATS 2021poster

Stochastic variational inference offers an attractive option as a default method for differentiable probabilistic programming. However, the performance of the variational approach depends on the choice of an appropriate variational family. Here, we introduce automatic structured variational inferenc…

2020

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

NeurIPS 2020spotlight

Traditional backpropagation of error, though a highly successful algorithm for learning in artificial neural network models, includes features which are biologically implausible for learning in real neural circuits. An alternative called target propagation proposes to solve this implausibility by us…

2020

The Indian Chefs Process

UAI 2020poster

This paper introduces the Indian chefs process (ICP) as a Bayesian nonparametric prior on the joint space of infinite directed acyclic graphs (DAGs) and orders that generalizes the Indian buffet process. As our construction shows, the proposed distribution relies on a latent Beta process controlling…

2019

Forward Amortized Inference for Likelihood-Free Variational Marginalization

AISTATS 2019poster

In this paper, we introduce a new form of amortized variational inference by using the forward KL divergence in a joint-contrastive variational loss. The resulting forward amortized variational inference is a likelihood-free method as its gradient can be sampled without bias and without requiring an…

Cited by 25SourcePDFScholar
2019

SpikeCaKe: Semi-Analytic Nonparametric Bayesian Inference for Spike-Spike Neuronal Connectivity

AISTATS 2019poster

In this paper we introduce a semi-analytic variational framework for approximating the posterior of a Gaussian processes coupled through non-linear emission models. While the semi-analytic method can be applied to a large class of models, the present paper is devoted to the analysis of causal connec…

Cited by 2SourcePDFScholar
2018

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

AISTATS 2018poster

Computing accurate estimates of the Fourier transform of analog signals from discrete data points is important in many fields of science and engineering. The conventional approach of performing the discrete Fourier transform of the data implicitly assumes periodicity and bandlimitedness of the signa…

Cited by 0SourcePDFScholar
2018

Wasserstein Variational Inference

NeurIPS 2018poster

This paper introduces Wasserstein variational inference, a new form of approximate Bayesian inference based on optimal transport theory. Wasserstein variational inference uses a new family of divergences that includes both f-divergences and the Wasserstein distance as special cases. The gradients of…

Cited by 61SourcePDFScholar
2017

GP CaKe: Effective brain connectivity with causal kernels

NeurIPS 2017poster

A fundamental goal in network neuroscience is to understand how activity in one brain region drives activity elsewhere, a process referred to as effective connectivity. Here we propose to model this causal interaction using integro-differential equations and causal kernels that allow for a rich anal…

Cited by 16SourcePDFScholar