Alex Lew

@alexlew.bsky.social

Theory & practice of probabilistic programming. Current: MIT Probabilistic Computing Project; Fall '25: Incoming Asst. Prof. at Yale CS

not sure how to get this across to non-academics but here goes, Imagine if you were suddenly told 'we decided not to pay your salary', that's kind of what the grant cuts felt like. Now imagine if you were suddenly told 'we are going to set your dog on fire', that's what this feels like:

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Many LM applications may be formulated as text generation conditional on some (Boolean) constraint. Generate a… - Python program that passes a test suite. - PDDL plan that satisfies a goal. - CoT trajectory that yields a positive reward. The list goes on… How can we efficiently satisfy these? 🧵👇

The New Yorker used to have human narrators do pretty great audio versions of selected articles. But then they quietly switched to generic, lifeless AI (with no indication until you click "Listen"). Occasionally they'll still have a human reader, like Sedaris here, and the contrast is insane

The New Yorker@newyorker.com · 2y ago

David Sedaris writes about travelling with his longtime partner, Hugh—and asking him if a stranded passenger could join their drive from Maine to New York. “The look he gave me was not one I had never seen before.”

Surprisal of title beginning with 'O'? 3.22 Surprisal of 'o' following 'Treatment '? 0.11 Surprisal that title includes surprisal of each title character? Priceless [...I did not know titles could do this]

Screenshot of the title of the paper "On the Proper Treatment of Tokenization in Psycholinguistics." Over each letter, the authors have plotted the surprisal of the letter (-log p(this letter | context)).
Marco@mcognetta.bsky.social · 2y ago

On the Proper Treatment of Tokenization in Psycholinguistics - aclanthology.org/2024.emnlp-m... - Nov 12 (Tue) 11:00-12:30 Leading Whitespaces of Language Models’ Subword Vocabulary Pose a Confound for Calculating Word Probabilities - aclanthology.org/2024.emnlp-m... - Nov 12 (Tue) 11:00-12:30

This is a very cool integration of LLMs + Bayesian methods. LLMs serve as *likelihoods*: how likely would the human be to have issued this (English) command, given a particular (symbolic) plan? No generation, just scoring :) A Bayesian agent can then resolve ambiguity in really sensible ways

Examples of the CLIPS agent from Zhi-Xuan, Ying et al. 2024 resolving ambiguity in human instructions.
xuan (ɕɥɛn / sh-yen)@xuanalogue.bsky.social · 2y ago

In some recent work we extended the original assistance game formalism to handle natural language, resulting in Language-Augmented Assistance Games. We then "solve" these games using an inverse planning algorithm, inferring goals from human instructions & natural language: arxiv.org/abs/2402.17930

Hi Bluesky! My claim to fame is the development of the Alexander Hamiltonian Monte Carlo algorithm. Younger researchers may not realize due to Moore's Law (Lin-Manuel Miranda becomes roughly half as cool every two years), but back when this was published in 2021, it was considered mildly topical

Algorithm box from the joke paper "Alexander Hamiltonian Monte Carlo."A proof of the main theorem from the paper, which is that the algorithm "eventually converges to the room where it happens, if the user is willing to wait for it."