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Cristopher Salvi

13 accepted papers

2025

SigDiffusions: Score-Based Diffusion Models for Time Series via Log-Signature Embeddings

ICLR 2025poster

Score-based diffusion models have recently emerged as state-of-the-art generative models for a variety of data modalities. Nonetheless, it remains unclear how to adapt these models to generate long multivariate time series. Viewing a time series as the discretisation of an underlying continuous proc…

Cited by 0SourcePDFScholar
2025

Signature Kernel Conditional Independence Tests in Causal Discovery for Stochastic Processes

ICLR 2025spotlight

Inferring the causal structure underlying stochastic dynamical systems from observational data holds great promise in domains ranging from science and health to finance. Such processes can often be accurately modeled via stochastic differential equations (SDEs), which naturally imply causal relation…

Cited by 14SourcePDFScholar
2025

Structured Linear CDEs: Maximally Expressive and Parallel-in-Time Sequence Models

NeurIPS 2025spotlight

This work introduces Structured Linear Controlled Differential Equations (SLiCEs), a unifying framework for sequence models with structured, input-dependent state-transition matrices that retain the maximal expressivity of dense matrices whilst being cheaper to compute. The framework encompasses exi…

Cited by 0SourceScholar
2024

Exact Gradients for Stochastic Spiking Neural Networks Driven by Rough Signals

NeurIPS 2024poster

We introduce a mathematically rigorous framework based on rough path theory to model stochastic spiking neural networks (SSNNs) as stochastic differential equations with event discontinuities (Event SDEs) and driven by càdlàg rough paths. Our formalism is general enough to allow for potential jumps…

2024

Theoretical Foundations of Deep Selective State-Space Models

NeurIPS 2024poster

Structured state-space models (SSMs) are gaining popularity as effective foundational architectures for sequential data, demonstrating outstanding performance across a diverse set of domains alongside desirable scalability properties. Recent developments show that if the linear recurrence powering S…

2023

Neural signature kernels as infinite-width-depth-limits of controlled ResNets

ICML 2023poster

Motivated by the paradigm of reservoir computing, we consider randomly initialized controlled ResNets defined as Euler-discretizations of neural controlled differential equations (Neural CDEs), a unified architecture which enconpasses both RNNs and ResNets. We show that in the infinite-width-depth l…

2023

Non-adversarial training of Neural SDEs with signature kernel scores

NeurIPS 2023poster

Neural SDEs are continuous-time generative models for sequential data. State-of-the-art performance for irregular time series generation has been previously obtained by training these models adversarially as GANs. However, as typical for GAN architectures, training is notoriously unstable, often suf…

2022

Neural Stochastic PDEs: Resolution-Invariant Learning of Continuous Spatiotemporal Dynamics

NeurIPS 2022accept

Stochastic partial differential equations (SPDEs) are the mathematical tool of choice for modelling spatiotemporal PDE-dynamics under the influence of randomness. Based on the notion of mild solution of an SPDE, we introduce a novel neural architecture to learn solution operators of PDEs with (possi…

Cited by 43SourcePDFScholar
2021

Distribution Regression for Sequential Data

AISTATS 2021poster

Distribution regression refers to the supervised learning problem where labels are only available for groups of inputs instead of individual inputs. In this paper, we develop a rigorous mathematical framework for distribution regression where inputs are complex data streams. Leveraging properties of…

2021

Higher Order Kernel Mean Embeddings to Capture Filtrations of Stochastic Processes

NeurIPS 2021poster

Stochastic processes are random variables with values in some space of paths. However, reducing a stochastic process to a path-valued random variable ignores its filtration, i.e. the flow of information carried by the process through time. By conditioning the process on its filtration, we introduce…

2021

Neural Rough Differential Equations for Long Time Series

ICML 2021spotlight

Neural controlled differential equations (CDEs) are the continuous-time analogue of recurrent neural networks, as Neural ODEs are to residual networks, and offer a memory-efficient continuous-time way to model functions of potentially irregular time series. Existing methods for computing the forward…

2021

SigGPDE: Scaling Sparse Gaussian Processes on Sequential Data

ICML 2021spotlight

Making predictions and quantifying their uncertainty when the input data is sequential is a fundamental learning challenge, recently attracting increasing attention. We develop SigGPDE, a new scalable sparse variational inference framework for Gaussian Processes (GPs) on sequential data. Our contrib…

Cited by 28SourcePDFScholar
2019

Deep Signature Transforms

NeurIPS 2019poster

The signature is an infinite graded sequence of statistics known to characterise a stream of data up to a negligible equivalence class. It is a transform which has previously been treated as a fixed feature transformation, on top of which a model may be built. We propose a novel approach which combi…