PhD candidate in Machine Learning @ETH_en and @MPI_IS. Working on foundation models for biology 🧬, model merging 🤝, and structured pruning ✂️.

Joined May 2024
Alexander Theus retweeted
1/ New preprint: GRASS-MIL, a tool for discovering which tumor architectures matter. From spatial single-cell data it maps the tissue neighborhoods tied to a clinical outcome, gives each an exact, signed contribution, and groups them into recurring niches. 🧵
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Self-supervised transcriptomic FMs are pretrained on millions of gene-expression profiles, yet often fail to beat simple supervised baselines on clinical tasks. Why? Our new work suggests the pretraining objective may matter more than scale. 📄arxiv.org/abs/2610.08694 1/8
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We also extend GeneICL to right-censored survival prediction, without survival-specific pretraining, using a reduction based on Cox residuals. Overall, our results suggest that in transcriptomics, how we pretrain may matter more than how large the model is. 8/8
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Really enjoyed working on this with Michael Bohl, @val_boeva, and David Wissel!
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Alexander Theus retweeted
Our Workshop on Weight-Space Symmetries @icmlconf @weightsymmetry is starting now! You can reach Room 403 by going up from Hall A. Program: weightsymmetry.com/schedule
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👇 Check out our new preprint: FPRM (Fixed-Point Reasoning Model). • No ACT head: loop to a fixed point, with convergence as the halt signal. • No hierarchy: a single loop beats HRM/TRM variants! • SOTA among 7M models: Sudoku-Extreme 94.2%, Maze-Hard 87.0%, ARC-AGI-1 47.5%.
Looped models scale compute by iterating in depth, demonstrating great potential in reasoning. But when should the looping stop, and how to keep it trainable at tens of thousands of unrolled layers? FPRM solves both. (1/7)
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This TRM variant makes a transformer block a contractive map, so that looping becomes a fixed-point process. They leverage this by approximating gradients with Neumann series (Truncated BPTT). Very cool work! 🔗arxiv.org/abs/2606.18206
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Alexander Theus retweeted
#ICLR2026 Into mode connectivity, model merging, or permutation invariance? We show how optimization dynamics shape the loss landscape of merged weights. Come check it out! 📅 23/04 10:30AM – 13:00PM 📍 Pavilion 3 P3-1809 w/ @TheusResearch @DamienTeney @orvieto_antonio
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📢 Submissions are OPEN for the Weight Space Symmetry Workshop @icmlconf! ⏰ Deadline extended → April 30 (23:59 AOE) Consider submitting any work related to weight symmetries: optimization, model merging, weight space learning, and so on! #ICML2026 #weightsymmetry2026
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📢Excited to announce the Workshop on Weight-Space Symmetries @icmlconf! We welcome 4-page submissions analysing symmetries, their effects on training and model structure, and practical methods to utilize them. Submission Deadline: April 24 (23:59 AoE) #ICML2026
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Excited to announce that our paper has been accepted as an Oral at NeurIPS 2025! 🥳
1/ 🚨 New paper alert! 🚨 We explore a key question in deep learning: Can independently trained Transformers be linearly connected in weight space — without a loss barrier? Yes — if you uncover their rich symmetries. 📄 arXiv: arxiv.org/abs/2506.22712
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1/ 🚨 New paper alert! 🚨 We explore a key question in deep learning: Can independently trained Transformers be linearly connected in weight space — without a loss barrier? Yes — if you uncover their rich symmetries. 📄 arXiv: arxiv.org/abs/2506.22712
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9/ 🔑 Takeaway: Transformers can be linearly connected — but only if you exploit richer network symmetries. We show that general symmetry alignment (not just permutations) unlocks low-loss paths across ViTs and GPT-2.
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