Improving Weather&Energy predictions at Gridmatic

Oxford
Joined September 2022
I have been long wanting to compare diffusion models to MCMC empirically. Running Langevin using the annealing scheme from diffusion models results in good samples even for hard targets. Details at jakiw.com/diffusion_as_annea… 1/n
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We can quickly create an annealing scheme that replicates that behaviour with the ansatz p_t = p(alpha_t x)^beta_t. This already works much better than the scheme employed before and is implementable. 6/n
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I don't imagine this is news to people with a background in simulated annealing, and I would love to get some input on what annealing schemes are actually used in practice nowadays! 7/n
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However, one can try to approximate such an annealing scheme by choosing p_t = p(alpha * x). A very short first attempt already improves upon the above annealing scheme! 6/n
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I am quite annealing schemes of this form already have to already. Would be very interested on any input on what annealing schemes people actually use nowadays in practice. 6/6
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For a Gaussian mixture, one can calculate the solution to the forward SDE in diffusion models/score-based generative models in closed form. Therefore, we can use this path as smoothed versions and plug it into a Langevin SDE. Turns out, this works nearly perfect! 4/6
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Intuitively, the modes for very smoothed out versions of p_t are all at 0. Then the modes move to their target destination, transporting the samples along with them. Unfortunately, for more complicated distributions, this annealing scheme cannot be computed. 5/6
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Jakiw Pidstrigach retweeted
Great technical explanation and implementation (JAX tutorial included) of diffusion models. jakiw.com/sgm_intro
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The Jupyter notebook here contains an introduction to SGMs using JAX: jakiw.com/sgm_intro It sets a focus on understanding some theoretical aspects as well as their generalization capabilities.
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I created them for the "Accelerating generative models and nonconvex optimisation" workshop at @turinginst. Thanks @odakyildiz for inviting me!
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Jakiw Pidstrigach retweeted
That's a wrap! :-) I really enjoyed this week I organised at @turinginst, exploring fundamental aspects of generative models. @TuringChiefSci See turing.ac.uk/research/theory… for details and send me a PM if you are interested!
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