Sam Power
@spmontecarlo.bsky.social
2.3K followers 1.9K following 1.1K posts
Lecturer in Maths & Stats at Bristol. Interested in probabilistic + numerical computation, statistical modelling + inference. (he / him). Homepage: https://sites.google.com/view/sp-monte-carlo Seminar: https://sites.google.com/view/monte-carlo-semina
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spmontecarlo.bsky.social
Another one, drafted for the same workshop, but which didn't quite make it - but which I hope will see some use at a future event!
spmontecarlo.bsky.social
It was fun! Mostly tutorials by the physicists for the statisticians; quite a success from that point of view. Recordings here: youtube.com/playlist?lis...
CoSInES-Bayes4Health Masterclass on Computational Physics, April 2024 - YouTube
youtube.com
spmontecarlo.bsky.social
A drafted logo for a past workshop (we ended up going with something else in the end, but I still find this one cute in its own way).
Reposted by Sam Power
spmontecarlo.bsky.social
I'll order these so that I can tick them off a list on my computer; the numbers are not any sort of ranking. Summaries will be kept brief and hopefully stoke curiosity, rather than providing answers.
spmontecarlo.bsky.social
Have been rather quiet on here recently (for uninteresting and unconcerning reasons), but this shouldn't be taken as a lack of enthusiasm for papers which have been coming out recently - loads of really clever and creative works popping up. Will try to post about some of them this afternoon!
spmontecarlo.bsky.social
This is indeed in the works (after combing through some of my folders of notes), but in the interim, I can share a few things which I've put up directly as .pdf files on my website (sites.google.com/view/sp-mont...), rather than as blog posts per se. Notes 3-5 are 'new'.
spmontecarlo.bsky.social
Regrettable that this reads to me as cognate to "cash my gold".
spmontecarlo.bsky.social
I guess it's really "zero-variance when it should be" (which is already difficult!) rather than "zero-variance in general" (which would be a miracle). A really nice work though; resolves a problem which I'm sure has bothered plenty of people (myself included) for some time.
spmontecarlo.bsky.social
Digest to be found here: bsky.app/profile/spmo...
spmontecarlo.bsky.social
I'll order these so that I can tick them off a list on my computer; the numbers are not any sort of ranking. Summaries will be kept brief and hopefully stoke curiosity, rather than providing answers.
spmontecarlo.bsky.social
Have been rather quiet on here recently (for uninteresting and unconcerning reasons), but this shouldn't be taken as a lack of enthusiasm for papers which have been coming out recently - loads of really clever and creative works popping up. Will try to post about some of them this afternoon!
spmontecarlo.bsky.social
27. arxiv.org/abs/2509.20083
'Rethinking player evaluation in sports: Goals above expectation and beyond'
- Robert Bajons, Lucas Kook

The 'expected goals' metric in football omits information about the player taking the shot. How can xG be adapted and extended to evaluate player efficacy?
spmontecarlo.bsky.social
26. arxiv.org/abs/2411.07041
'Stochastic parameterisation: the importance of nonlocality and memory'
- Martin T. Brolly

Given a spatially-localised, Markovian-in-time dynamical system, 'optimal' reduced-order modelling can often compromise one or both of these features. (How) shall we recover them?
spmontecarlo.bsky.social
25. arxiv.org/abs/2508.10782
'Dimension-Free Bounds for Generalized First-Order Methods via Gaussian Coupling'
- Galen Reeves

Approximate Message-Passing algorithms can be tricky to parse, due to their grounding in large-system asymptotics. A more finitary treatment is both possible and insightful.
Dimension-Free Bounds for Generalized First-Order Methods via Gaussian Coupling
We establish non-asymptotic bounds on the finite-sample behavior of generalized first-order iterative algorithms -- including gradient-based optimization methods and approximate message passing (AMP) ...
arxiv.org
spmontecarlo.bsky.social
24. arxiv.org/abs/2510.00389
'Zero variance self-normalized importance sampling via estimating equations'
- Art B. Owen

Even with optimal proposals, achieving zero variance with SNIS-type estimators requires some innovative thinking. This work explains how an optimisation formulation can apply.
spmontecarlo.bsky.social
23. arxiv.org/abs/2509.16062
'Transient regime of piecewise deterministic Monte Carlo algorithms'
- Sanket Agrawal, Joris Bierkens, Kengo Kamatani, Gareth O. Roberts

The out-of-equilibrium behaviour of certain MCMC algorithms can exhibit rather different features to the equilibrium behaviour.
spmontecarlo.bsky.social
22. arxiv.org/abs/1910.10667
'Extreme value statistics of correlated random variables: a pedagogical review'
- Satya N. Majumdar, Arnab Pal, Gregory Schehr

Extremes are well-understood in the iid case; weakly-dependent systems are often qualitatively similar. Strong dependence yields new phenomena.
spmontecarlo.bsky.social
21. arxiv.org/abs/2402.07048
'Logistic-beta processes for dependent random probabilities with beta marginals'
- Changwoo J. Lee, Alessandro Zito, Huiyan Sang, David B. Dunson

Modelling of spatial dependence becomes challenging outside of the Gaussian setting - could latent Gaussianity suffice?
spmontecarlo.bsky.social
20. math.nyu.edu/~kohn/papers/kohn-serfaty-cpam.pdf
'A deterministic-control-based approach to motion by curvature'
- Robert Kohn, Sylvia Serfaty

Can deterministic control problems give rise to HJB PDEs which softly imply the presence of underlying stochasticity?
spmontecarlo.bsky.social
19. arxiv.org/abs/2507.14535
'Inference for Diffusion Processes via Controlled Sequential Monte Carlo and Splitting Schemes'
- Shu Huang, Richard G. Everitt, Massimiliano Tamborrino, Adam M. Johansen

How shall we best discretise dynamical systems for the purpose of conducting inference?
spmontecarlo.bsky.social
18. arxiv.org/abs/2509.19707
'Diffusion and Flow-based Copulas'
-David Huk, Theodoros Damoulas

If a distribution has standard Gaussian marginals, then one can smoothly interpolate it towards an exact Gaussian along a path which never changes those marginals, only altering the copula.
spmontecarlo.bsky.social
17. arxiv.org/abs/1807.00027 + arxiv.org/abs/2508.19648

'Bounds on the Poincaré constant for convolution measures'
- Thomas A. Courtade
'Subadditivity of the log-Sobolev constant on convolutions'
- Thomas A. Courtade, Edric Wang

How does convolution interact with 'strong' concentration of measure?
spmontecarlo.bsky.social
16. arxiv.org/abs/2510.01901
'Knots and variance ordering of sequential Monte Carlo algorithms'
- Joshua J Bon, Anthony Lee

Can one ever say that one Feynman-Kac representation of a probability measure is 'strictly better' than another, from an estimation point of view?
spmontecarlo.bsky.social
15. arxiv.org/abs/2502.18475
'Least squares variational inference'
- Yvann Le Fay, Nicolas Chopin, Simon Barthelmé

Variational inference is based on a minimisation problem, the stationarity condition for which yields an equation to be solved. Can one attack that stationary condition directly?
spmontecarlo.bsky.social
14. arxiv.org/abs/2509.08619
'A hierarchical entropy method for the delocalization of bias in high-dimensional Langevin Monte Carlo'
- Daniel Lacker, Fuzhong Zhou

Bias bounds for unadjusted MCMC methods can often appear pessimistic in practice. Under what circumstances might things be better?
spmontecarlo.bsky.social
13. arxiv.org/abs/2510.01933
'Central Path Art'
- Thor Catteau, Benjamin Glancy, Allen Holder, Angela Milkowski, Alexa Renner, Connor Tasik, Rebecca Testa

The interior-point method is effective for solving convex optimisation problems. Can it also be effective for generating art?