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Ellen Vitercik

@ellen-v.bsky.social
791 followers 120 following 35 posts

MS&E + CS assistant professor at Stanford. I study reliable AI for algorithmic reasoning, optimization, and decision-making. vitercik.github.io

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Ellen Vitercik @ellen-v.bsky.social · 01/09/2026
Paper: arxiv.org/abs/2608.25220 Code + benchmark: flare.henryrobbins.com Led by my student Henry Robbins, with @lawlessopt.bsky.social and Madeleine Udell. Benchmark: 20 problems, 109 formulations, 63 valid pairs with Lean proofs, and 26 invalid pairs.
arxiv.org
FLARE: Verifying MILP Reformulations with LLM-Based Theorem Proving
Mixed-Integer Linear Programming (MILP) is a fundamental tool for combinatorial optimization with extensive real-world applications. A central challenge is designing computationally efficient MILP for...
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Ellen Vitercik @ellen-v.bsky.social · 01/09/2026
On 54 reformulation pairs of NP-hard problems, FLARE correctly classified all (best baseline: 83%) and provided a machine-checkable proof for every accepted reformulation. AI-generated optimization needs proofs; passing tests isn’t enough.
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Ellen Vitercik @ellen-v.bsky.social · 01/09/2026
LLMs can rewrite your optimization problem to improve solve time, pass every test, and still silently change the problem. Our new paper introduces FLARE, an LLM agent that uses Lean to prove that a MILP reformulation is valid across all possible problem instances, not just those used for testing.
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Ellen Vitercik @ellen-v.bsky.social · 26/08/2026
LLMs can make optimization more accessible, but they must not sacrifice the guarantees that make solvers trustworthy. This was the focus of my part of our @ijcai.org tutorial, Large Language Models for Optimization, w/ Fei Liu & @lawlessopt.bsky.social. Materials: feiliu36.github.io/llm_opt_tuto...
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Ellen Vitercik @ellen-v.bsky.social · 18/05/2026
Slides: vitercik.github.io/assets/pdf/U... MAGNOLIA: Matching Algorithms via GNNs for Online Value-to-go Approximation: arxiv.org/abs/2406.05959 Algorithms with Calibrated Machine Learning Predictions: arxiv.org/abs/2502.02861 (🧵 7/7)
arxiv.org
MAGNOLIA: Matching Algorithms via GNNs for Online Value-to-go Approximation
Online Bayesian bipartite matching is a central problem in digital marketplaces and exchanges, including advertising, crowdsourcing, ridesharing, and kidney exchange. We introduce a graph neural netwo...
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Ellen Vitercik @ellen-v.bsky.social · 18/05/2026
We investigate the value of calibration in online rent-or-buy and online job scheduling, with guarantees depending on accuracy, calibration error, sharpness, and inherent uncertainty. Joint work with @heyyjudes.bsky.social and Anders Wikum. ICML 2025 Spotlight. (🧵 6/7)
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Ellen Vitercik @ellen-v.bsky.social · 18/05/2026
2. Calibration for online decision-making Predictions can improve online algorithms, but errors can compound through sequential decisions. Calibration gives a statistical way to reason about when predictions should be trusted, and when an algorithm should behave more conservatively. (🧵 5/7)
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Ellen Vitercik @ellen-v.bsky.social · 18/05/2026
The theory question is: Why should local message-passing be appropriate for this task? For random geometric graphs, we show that value-to-go (VTG) is nearly local. This gives a structural justification for using GNNs. Joint with Alexandre Hayderi, Amin Saberi, and Anders Wikum. ICML 2024. (🧵 4/7)
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Ellen Vitercik @ellen-v.bsky.social · 18/05/2026
1. GNNs for online matching In Online Bayesian Bipartite Matching, decisions are irrevocable and future arrivals are uncertain. We use GNNs to approximate marginal value-to-go functions: the value of matching now relative to skipping and waiting for a higher reward later. (🧵 3/7)
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Ellen Vitercik @ellen-v.bsky.social · 18/05/2026
Discrete optimization problems are central across logistics, energy, marketplaces, healthcare, and other domains. Historical instances often contain useful structure, but properly exploiting that structure requires more than dropping in a generic ML model. My talk focused on 2 case studies. (🧵 2/7)
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Ellen Vitercik @ellen-v.bsky.social · 18/05/2026
Can machine learning improve discrete optimization algorithms without sacrificing theoretical guarantees? This was the central question of the talk I gave this spring at a few schools (UCSD, UIC, Yale, Penn): Machine Learning for Discrete Optimization: Theoretical Foundations. (🧵 1/7)
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Ellen Vitercik @ellen-v.bsky.social · 01/05/2026
More time to submit to LAMP 2026! The deadline for spotlight talks, posters, and open problems has been extended to May 14. Learn more and submit: dravy.ttic.edu/lamp26.html
dravy.ttic.edu
LAMP Workshop — ML-assisted theory
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Reposted by Ellen Vitercik
TTIC @tticconnect.bsky.social · 27/04/2026
Nina Balcan, Avrim Blum, Piotr Indyk & Ali Vakilian are organizing a #STOC2026 Workshop on Machine Learning for Algorithms, featuring tutorials, talks & a poster session. Learn more and submit your poster by June 1: buff.ly/JdQci1c
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Ellen Vitercik @ellen-v.bsky.social · 22/04/2026
Learn more and submit: dravy.ttic.edu/lamp26.html
dravy.ttic.edu
LAMP Workshop — ML-assisted theory
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Ellen Vitercik @ellen-v.bsky.social · 22/04/2026
We welcome spotlight talks, posters, and open problems at the intersection of machine learning and theoretical computer science. We have an exciting lineup of speakers from academia and industry, and we’re looking forward to bringing this emerging community together.
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Ellen Vitercik @ellen-v.bsky.social · 22/04/2026
We’re excited to announce the call for submissions for our workshop on Learning-driven Algorithms and Machine-aided Proofs (LAMP) at Toyota Technical Institute of Chicago (@tticconnect.bsky.social) on August 6–7. Huge thanks to my co-organizers Sandeep Silwal and Dravyansh Sharma.
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Ellen Vitercik @ellen-v.bsky.social · 27/01/2026
The main conceptual contribution is a way to sidestep the Ω(log n) barrier introduced by standard probabilistic metric embeddings. Instead, Yingxi & Mingwei found a clever way to bound our algorithm’s cost directly on a deterministic embedding & compare it to OPT, bounded via majorization arguments.
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Ellen Vitercik @ellen-v.bsky.social · 27/01/2026
We: • Move 𝗯𝗲𝘆𝗼𝗻𝗱 the standard 𝗶.𝗶.𝗱. model: each request comes from its own distribution with a mild smoothness condition. • Require 𝗻𝗼 𝗱𝗶𝘀𝘁𝗿𝗶𝗯𝘂𝘁𝗶𝗼𝗻𝗮𝗹 𝗸𝗻𝗼𝘄𝗹𝗲𝗱𝗴𝗲: we use only one sample from each request distribution. • Achieve an 𝗢(𝟭) competitive ratio for d-dimensional Euclidean metrics for d > 2.
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Ellen Vitercik @ellen-v.bsky.social · 27/01/2026
We study a classic online metric matching problem in which n servers (e.g., rideshare drivers) are available in advance and n requests (e.g., riders) arrive one by one. Each request must be immediately matched to an available server, paying the distance between the two in an underlying metric.
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Ellen Vitercik @ellen-v.bsky.social · 27/01/2026
arXiv: arxiv.org/abs/2510.20288
arxiv.org
Smoothed Analysis of Online Metric Matching with a Single Sample: Beyond Metric Distortion
In the online metric matching problem, $n$ servers and $n$ requests lie in a metric space. Servers are available upfront, and requests arrive sequentially. An arriving request must be matched immediat...
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Ellen Vitercik @ellen-v.bsky.social · 27/01/2026
This week at the Innovations in Theoretical Computer Science (ITCS) conference, Mingwei Yang is presenting our paper: 𝗦𝗺𝗼𝗼𝘁𝗵𝗲𝗱 𝗔𝗻𝗮𝗹𝘆𝘀𝗶𝘀 𝗼𝗳 𝗢𝗻𝗹𝗶𝗻𝗲 𝗠𝗲𝘁𝗿𝗶𝗰 𝗠𝗮𝘁𝗰𝗵𝗶𝗻𝗴 𝘄𝗶𝘁𝗵 𝗮 𝗦𝗶𝗻𝗴𝗹𝗲 𝗦𝗮𝗺𝗽𝗹𝗲: 𝗕𝗲𝘆𝗼𝗻𝗱 𝗠𝗲𝘁𝗿𝗶𝗰 𝗗𝗶𝘀𝘁𝗼𝗿𝘁𝗶𝗼𝗻 by Yingxi Li, myself, and Mingwei Yang See Mingwei's talk here: youtu.be/yEBPI9c7OE8?...
youtu.be
ITCS 2026 - Smoothed Analysis of Online Metric Matching with a Single Sample
YouTube video by Mingwei Yang
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Ellen Vitercik @ellen-v.bsky.social · 20/01/2026
Tutorial page (agenda + reading list): conlaw.github.io/llm_opt_tuto... Thanks to Léonard Boussioux and Madeleine Udell for helping put the proposal together.
conlaw.github.io
LLMs for Optimization Tutorial
Fair Clustering Tutorial
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Ellen Vitercik @ellen-v.bsky.social · 20/01/2026
Optimization is central to planning, scheduling, and decision-making, but deploying solvers requires deep expertise. Our tutorial covers how LLMs can support the end-to-end optimization pipeline (model formulation, solver configuration, and model validation) and highlights open research directions.
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Ellen Vitercik @ellen-v.bsky.social · 20/01/2026
@lawlessopt.bsky.social and I are excited to present our #AAAI2026 tutorial on “LLMs for Optimization: Modeling, Solving, and Validating with Generative AI.” When: Tuesday, Jan 20, 2026, 8:30am–12:30pm SGT Where: Garnet 216 (Singapore EXPO) (Connor’s intro slides are shown here.) CC @aaai.org
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Ellen Vitercik @ellen-v.bsky.social · 02/12/2025
Topic 4: Theoretical Guarantees - Optimizing Solution-Samplers for Combinatorial Problems: The Landscape of Policy-Gradient Methods (Caramanis et al., NeurIPS’23) - Approximation Algorithms for Combinatorial Optimization with Predictions (Antoniadis et al., ICLR’25)
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Ellen Vitercik @ellen-v.bsky.social · 02/12/2025
Topic 3: Math Optimization - OptiMUS-0.3: Using LLMs to Model and Solve Optimization Problems at Scale (AhmadiTeshnizi et al., arXiv’25) - Contrastive Predict-and-Search for Mixed Integer Linear Programs (Huang et al., ICML’24) - Differentiable Integer Linear Programming (Geng et al., ICLR’25)
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Ellen Vitercik @ellen-v.bsky.social · 02/12/2025
Topic 2: Graph Neural Networks - One Model, Any CSP: GNNs as Fast Global Search Heuristics for Constraint Satisfaction (Tönshoff et al., IJCAI’23) - Dual Algorithmic Reasoning (Numeroso et al., ICLR’23) - DIFUSCO: Graph-based Diffusion Solvers for Combinatorial Optimization (Sun & Yang, NeurIPS’23)
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Ellen Vitercik @ellen-v.bsky.social · 02/12/2025
Topic 1: Transformers & LLMs - What Learning Algorithm is In-Context Learning? (Akyürek et al., ICLR’23) - Transformers as Statisticians (Bai et al., NeurIPS’23) - We Need An Algorithmic Understanding of Generative AI (Eberle et al., ICML’25) - Evolution of Heuristics (Liu et al., ICML’24)
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Ellen Vitercik @ellen-v.bsky.social · 02/12/2025
I’m excited to share the materials from my Stanford seminar course, “AI for Algorithmic Reasoning and Optimization”: vitercik.github.io/ai4algs_25/. It covered formal algorithmic frameworks for analyzing LLM reasoning, GNNs for combinatorial/mathematical optimization, and theoretical guarantees.
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Ellen Vitercik @ellen-v.bsky.social · 16/11/2025
On top of his research, my PhD students and I can attest that he’s a thoughtful, generous collaborator and mentor. Please don’t hesitate to reach out if you’d like me to share my very strong recommendation letter. (Photo credit: @cpaior.bsky.social.)
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Ellen Vitercik @ellen-v.bsky.social · 16/11/2025
Connor has done exciting work on leveraging LLMs to model and solve large-scale optimization problems (arxiv.org/abs/2407.19633, arxiv.org/abs/2412.12038), developing mathematical optimization tools to make ML models more interpretable (arxiv.org/abs/2502.16380), among many other contributions.
arxiv.org
OptiMUS-0.3: Using Large Language Models to Model and Solve Optimization Problems at Scale
Optimization problems are pervasive in sectors from manufacturing and distribution to healthcare. However, most such problems are still solved heuristically by hand rather than optimally by state-of-t...
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Ellen Vitercik @ellen-v.bsky.social · 16/11/2025
Please keep an eye out for Connor Lawless (@lawlessopt.bsky.social) on the faculty job market! Connor is a Stanford Human-Centered AI Postdoc, co-hosted by myself and Madeleine Udell. His research combines ML, computational optimization, and HCI, with the goal of building human-centered AI systems.
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Connor Lawless @lawlessopt.bsky.social · 14/07/2025
Excited to be chatting about our new paper "Understanding Fixed Predictions via Confined Regions" (joint work with @berkustun.bsky.social, Lily Weng, and Madeleine Udell) at #ICML2025! 🕐 Wed 16 Jul 4:30 p.m. PDT — 7 p.m. PDT 📍East Exhibition Hall A-B #E-1104 🔗 arxiv.org/abs/2502.16380
arxiv.org
Understanding Fixed Predictions via Confined Regions
Machine learning models can assign fixed predictions that preclude individuals from changing their outcome. Existing approaches to audit fixed predictions do so on a pointwise basis, which requires ac...
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Reposted by Ellen Vitercik
Yu He @dransyhe.bsky.social · 13/07/2025
Our ✨spotlight paper✨ "Primal-Dual Neural Algorithmic Reasoning" is coming to #ICML2025! We bring Neural Algorithmic Reasoning (NAR) to the NP-hard frontier 💥 🗓 Poster session: Tuesday 11:00–13:30 📍 East Exhibition Hall A-B, # E-3003 🔗 openreview.net/pdf?id=iBpkz... 🧵
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Reposted by Ellen Vitercik
Divyarthi Mohan @divyarthi.bsky.social · 02/07/2025
Join us for a Wikipedia edit-a-thon at #ACMEC25! When: July 8th, 8PM-10PM Where: Stanford Econ Landau 139 Website: sites.google.com/view/econcs-... Come hangout, grab snacks, and edit/create Wikipedia pages for EC topics. Suggest topics/articles that need attention: docs.google.com/spreadsheets...
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Ellen Vitercik @ellen-v.bsky.social · 05/04/2025
Congrats Kira!!
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Reposted by Ellen Vitercik
Connor Lawless @lawlessopt.bsky.social · 16/03/2025
Super excited about this new work with Yingxi Li, Anders Wikun, @ellen-v.bsky.social, and Madeleine Udell forthcoming at CPAIOR2025: LLMs for Cold-Start Cutting Plane Separator Configuration 🔗: arxiv.org/abs/2412.12038
arxiv.org
LLMs for Cold-Start Cutting Plane Separator Configuration
Mixed integer linear programming (MILP) solvers ship with a staggering number of parameters that are challenging to select a priori for all but expert optimization users, but can have an outsized impa...
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Ellen Vitercik @ellen-v.bsky.social · 12/12/2024
Pulled a shoulder muscle trying to stay cool on the golf course in front of my PhD students and postdoc 😅 🏌‍♀️
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Reposted by Ellen Vitercik
Gautam Kamath @gautamkamath.com · 10/12/2024
📢 Join us at #NeurIPS2024 for an in-person Learning Theory Alliance mentorship event! 📅 When: Thurs, Dec 12 | 7:30-9:30 PM PST 🔥 What: Fireside chat w/ Misha Belkin (UCSD) on Learning Theory Research in the Era of LLMs, + mentoring tables w/ amazing mentors. Don’t miss it if you’re at NeurIPS!
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Ellen Vitercik @ellen-v.bsky.social · 19/11/2024
Hi Emily, could you please add me? Thanks for making it!
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Ellen Vitercik @ellen-v.bsky.social · 18/11/2024
Can you add me? 😀
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