Abel Jansma's Avatar

Abel Jansma

@abelaer

Emergence and compositionality in complex and living systems || Fellow @emergenceDIEP, University of Amsterdam || prev at MPI Leipzig & Un. of Edinburgh abeljansma.nl

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08.10.2023
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Latest posts by Abel Jansma @abelaer

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Every year, our apricot is the first to blossom, which is easy to remember because “apricot” shares a linguistic root with “precocious”.

10.03.2026 06:17 👍 2 🔁 0 💬 0 📌 0

I hope that when I'm 88 I'm also still able to embrace new technologies with such joy and curiosity:

www-cs-faculty.stanford.edu/~knuth/paper...

04.03.2026 09:22 👍 1 🔁 0 💬 0 📌 0

I think people just disagree on what representing something with a graph means. You seem to mean something very specific, along the lines of eq. 4. But if I want to represent the interactions of an up-to n-th order Ising model, a hypergraph can do that, and a pairwise graph can't--you need 2^n dof.

23.02.2026 14:16 👍 1 🔁 0 💬 2 📌 0

ok let's make a list of all ℵ₀ genders then. Now construct a new flag where the color of the first band differs from that of the 1st gender's flag, the color of the second band differs from that of the 2nd gender, etc. This defines a new gender that was not in your list of ℵ₀ genders. □

16.12.2025 13:44 👍 3 🔁 0 💬 1 📌 0
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I found this surprising and somewhat worrying: openAI is using an AI model to align their model spec. #NeurIPS2025

02.12.2025 18:32 👍 1 🔁 0 💬 0 📌 0
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I Figured Out How to Engineer Emergence What's come of my return to science

🔗 Erik’s post: theintrinsicperspective.com/p/i-figured-...

🔗 The paper: arxiv.org/abs/2510.02649

22.10.2025 17:25 👍 1 🔁 0 💬 0 📌 0
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A few months ago I started discussing causal emergence with Erik Hoel.
This led to a really fun collaboration, and a new approach to “engineer emergence”.

Erik just published an overview of the ideas, goals, and dreams:

22.10.2025 17:24 👍 2 🔁 0 💬 1 📌 0
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I know you like showing pictures of lenses but this seems a little excessive

14.10.2025 19:54 👍 1 🔁 0 💬 0 📌 0
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Many sea stars begin life as young fairy-like creature (called a brachiolaria) that float through the open ocean. Eventually, a small star forms within them (here in yellow). The fairy-like brachiolaria sinks under the star’s weight, and the star pops out!
🎥@the_story_of_a_biologist (on Insta)

09.10.2025 04:24 👍 511 🔁 181 💬 7 📌 15

There's so much more in the paper, largely thanks to Patrick who really pushed this to the next level. We're already working on applications: SVs are often used for XAI, but now we can do this for vector-valued functions--the kind implemented by transformers... Stay tuned!

08.10.2025 14:49 👍 1 🔁 0 💬 1 📌 0

To summarise:
⬆️Möbius inversions construct higher-order structure.
⬇️Shapley values project this down again, in the 'right' way.

We derive generalisations of both, to directed acyclic multigraphs, and group-valued functions.

08.10.2025 14:49 👍 2 🔁 0 💬 1 📌 0
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This shows how intimately related Shapley values and Möbius inversions are: we derive an expression that expresses Shapley values *purely in terms of the incidence algebra*!

08.10.2025 14:49 👍 2 🔁 0 💬 1 📌 0
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Doing so required also generalising the Möbius inversion theorem to this setting (prev. only defined for ring-valued functions). We show that it's a natural theorem in the *path algebra* of the graph:

08.10.2025 14:49 👍 1 🔁 0 💬 1 📌 0
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But we go further.
Classical Shapley values only work for real-valued functions on power sets of players (or lattices).

We generalise them even beyond posets to
✅vector/group-valued fns
✅weighted directed acyclic multigraphs
, and prove uniqueness!

08.10.2025 14:49 👍 1 🔁 0 💬 1 📌 0
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That’s exactly what we do.
We reinterpret Shapley values as projection operators: a recursive re-attribution of higher-order synergy to lower-order parts.

This turns Shapley values into a general projection framework for hierarchical structure, valid far beyond game theory.

08.10.2025 14:49 👍 3 🔁 0 💬 1 📌 0
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Möbius inversions are a way to derive higher-order interactions ion a system's mereology. I wrote a blog post about this here 👉https://abeljansma.nl/2025/01/28/mereoPhysics.html

If Shapley values are truly general, we should be able to express them for any Möbius inversion/higher-order structure.

08.10.2025 14:49 👍 2 🔁 0 💬 1 📌 0

But Shapley values (SVs) aren’t just about fairness.
They're really a projection operator: the right way to push higher-order structure back down to lower levels.
So… can we do this more generally? 🤔

Enter Möbius inversions...

08.10.2025 14:49 👍 1 🔁 0 💬 1 📌 0

If a group of people earn a payoff together, how should it be fairly distributed?
Shapley values are weighted sums of sub-coalition "synergies", and provably the fairest possible distribution.
It earned Shapley the Nobel Prize. 🧮

08.10.2025 14:49 👍 1 🔁 0 💬 1 📌 0
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Möbius transforms and Shapley values for vector-valued functions on weighted directed acyclic multigraphs We generalize the concept of Möbius inversion and Shapley values to directed acyclic multigraphs and weighted versions thereof. We further allow value functions (games) and thus their Möbius transform...

🚨New paper: arxiv.org/abs/2510.05786

*Shapley values beyond game theory*
We show that Shapley values aren’t just about dividing payoffs--they are the right way to project down any higher-order structure.

We generalise them, and Möbius inversions, in important ways: 🧵

08.10.2025 14:49 👍 10 🔁 3 💬 1 📌 0
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This is how Rota originally introduced the incidence algebra. Everyone since has (correctly) required the ring to be commutative. Did people in the '60s just refer to commutative rings as associative rings?

23.09.2025 19:11 👍 0 🔁 0 💬 0 📌 0

Just to balance out the discourse: the #NeurIPS2025 review process for this paper went great. Fair reviews, mostly responsive reviewers, and a thoughtful AC that caught a possible conflict of interest. Definitely improved the paper.

23.09.2025 11:46 👍 1 🔁 0 💬 0 📌 0

The #NeurIPS2025 version is now online: arxiv.org/pdf/2501.11447

It includes a new analysis to show that LLM semantics can be decomposed: the negativity of "horribly bad" is redundantly encoded in the two words, whereas "not bad" has synergistic semantics (i.e. negation):

22.09.2025 07:58 👍 3 🔁 0 💬 0 📌 1

The "partial causality decomposition" was just accepted for a spotlight at #NeurIPS2025!

The final version includes a decomposition of LLM semantics---the Arxiv version should be updated soon. Stay tuned!

19.09.2025 11:01 👍 1 🔁 0 💬 0 📌 0
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Dutch Institute for Emergent Phenomena

Hi! sorry I'm not on often on this site. They're now online: www.youtube.com/@dutchinstit...

12.08.2025 12:00 👍 0 🔁 0 💬 1 📌 0
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While I'm flattered, it's a bit weird that google's AI defers to me when you search for this:

05.08.2025 11:57 👍 0 🔁 0 💬 0 📌 0

Yes!

14.05.2025 18:03 👍 0 🔁 0 💬 1 📌 0
WORKSHOPANALOGIES | DIEP

Next week we're organising a workshop on the role of analogies in (artificial) intelligence, with:

Melanie Mitchell (@melaniemitchell.bsky.social), Martha Lewis, Jules Hedges (‪@julesh.mathstodon.xyz.ap.brid.gy‬), and Han van der Maas.

Register here: www.d-iep.org/workshopanal...

06.05.2025 07:07 👍 5 🔁 1 💬 2 📌 2

Don't take my word for it--take Reviewer 2's: "I found the paper extremely interesting and deep"

A gentle introduction is available at abeljansma.nl/2025/01/28/m...

08.04.2025 13:08 👍 1 🔁 0 💬 0 📌 0
Mereological approach to higher-order structure in complex systems: From macro to micro with M\"obius Relating macroscopic observables to microscopic interactions is a central challenge in the study of complex systems. While current approaches often focus on pairwise interactions, a complete understan...

My new approach to higher-order interactions in complex systems is now published in Physical Review Research:
journals.aps.org/prresearch/a...

08.04.2025 13:07 👍 2 🔁 1 💬 1 📌 1

The link doesn’t seem to work for me

07.02.2025 21:52 👍 0 🔁 0 💬 1 📌 0