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Posts by Marlos C. Machado

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Wake up Samurai, RLVG IS BACK! ๐Ÿ˜Ž

We are happy to announce the awesome speakers of the second edition of the RLVG workshop: @alexkearney.com, @marloscmachado.bsky.social, Martin Singh-Bloom, Sam Devlin, Pete Wurman and @neuroai.bsky.social!

Join us August 15th at @rl-conference.bsky.social!

2 days ago 16 6 1 0
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From Pixels to Place Cells: Where Representation Learning Meets Neuroscience I have been itching to talk about a paper we put out on bioRxiv last year, and I finally found the time to write about it. This is aโ€ฆ

This work was led by Diego Gomez (tarod13.github.io), in collaboration with
@michaelhbowling.bsky.social and @jquinnlee.bsky.social. What an environment we have here at @ualberta.bsky.social and @amiithinks.bsky.social!

Preprint: biorxiv.org/content/10.1...

Blog post: medium.com/@marlos.chol...

4 weeks ago 1 0 0 0
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Are these results real? We then replicated experiments that measured cell activations in the hippocampus of mice during remapping experiments. We observed the NNs we trained performing quite similarly to the neural data from previous work! ๐Ÿคฏ๐Ÿคฏ๐Ÿคฏ

Ref: www.cell.com/neuron/fullt...

4 weeks ago 1 0 1 0

In other words, the successor representation shows up immediately before grid cells, similarly to how the hippocampus (where place cells are) comes after the entorhinal cortex (to understand the direction, think about what influences what when performing backprop in an ANN).

4 weeks ago 1 0 1 0
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Moreover, we see activations resembling place cells in the 3rd layer and border and corner cells in the 1st and 2nd layers (and many other cell types). These results showed the formation of a representational loop consistent with anatomical and functional circuits in the brain.

4 weeks ago 1 0 1 0
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First, we showed that when training a neural network to estimate, from high-dimensional observations, the eigenvectors of the successor representation (or graph Laplacian), we see activation patterns resembling those in the entorhinal cortex. In fact, we see many of those!

4 weeks ago 1 0 1 0
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From Pixels to Place Cells: Where Representation Learning Meets Neuroscience I have been itching to talk about a paper we put out on bioRxiv last year, and I finally found the time to write about it. This is aโ€ฆ

A couple of months ago, we released a preprint of one of my favourite papers Iโ€™ve ever written. It lies at the intersection of representation learning and neuroscience. I have now written a blog post about it.

Preprint: biorxiv.org/content/10.1...

Blog post: medium.com/@marlos.chol...

4 weeks ago 3 0 1 0
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Government of Canada launches new initiative to recruit world-leading researchers - Canada.ca Canada will invest $1.7 billion to attract top global talent

"Canada Impact+ Research Chairs programโ€”a new $1 billion investment that will provide Canadian institutions the opportunity to recruit top-tier international researchers with expertise in key areas ..."

www.canada.ca/en/innovatio...

4 months ago 2 0 0 0

Thrilled to start 2026 as faculty in Psych & CS
@ualberta.bsky.social + Amii.ca Fellow! ๐Ÿฅณ Recruiting students to develop theories of cognition in natural & artificial systems ๐Ÿค–๐Ÿ’ญ๐Ÿง . Find me at #NeurIPS2025 workshops (speaking coginterp.github.io/neurips2025 & organising @dataonbrainmind.bsky.social)

4 months ago 105 27 4 1
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The Computing Science Dept. at the University of Alberta has multiple faculty job openings. Please share this broadly. We have a great environment!

- CS Theory: tinyurl.com/zrh9mk69
- Network/Cyber Security: tinyurl.com/renxazzy
- Robotics/CV/Graphics: tinyurl.com/ypcsfbff

4 months ago 9 2 0 0

The Department of Computing Science at the University of Alberta at the University of Alberta has an opening for another tenure-track faculty in robotics. Please, spread the word.

I can attest to how awesome our department and @amiithinks.bsky.social are!

(Official job posting coming soon.)

5 months ago 3 0 0 0
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Ratatouille (2007)

6 months ago 6 0 0 0

This paper has now been accepted @neuripsconf.bsky.social !

Huge congratulations, Hon Tik (Rick) Tse and Siddarth Chandrasekar.

7 months ago 8 3 0 0

2/2: โ€œConquerors live in dread of the day when they are shown to be, not superior, but simply lucky.โ€

โ€• N.K. Jemisin, The Stone Sky

7 months ago 2 0 0 0

1/2: But there are none so frightened, or so strange in their fear, as conquerors. They conjure phantoms endlessly, terrified that their victims will someday do back what was done to themโ€”even if, in truth, their victims couldnโ€™t care less about such pettiness and have moved on.โ€

7 months ago 2 1 1 0
RLC 2025 - Outstanding Paper Awards

Excited to announce the RLC best paper awards! Like last year, we wanted to highlight the many excellent ways you can do research.
rl-conference.cc/RLC2025Award...

8 months ago 10 6 0 1

* RLC Journal to Conference Track:*
(Originally published at TMLR)

- Deep RL track (Thu): AGaLiTe: Approximate Gated Linear Transformers for Online Reinforcement Learning by S. Pramanik

8 months ago 1 0 0 0
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* RLC Full Papers:*
(These are great papers!)

- Deep RL track (Thu): Deep Reinforcement Learning with Gradient Eligibility Traces by E. Elelimy
- Foundations track (Fri): An Analysis of Action-Value Temporal-Difference Methods That Learn State Values by B. Daley and P. Nagarajan

8 months ago 1 0 1 0

* RLC Workshop Papers (2/2):*
Inductive Biases in RL
sites.google.com/view/ibrl-wo...

- A Study of Value-Aware Eigenoptions by H. Kotamreddy

8 months ago 0 0 1 0
Workshop on Reinforcement Learning Beyond Rewards: Ingredients for Developing Generalist Agents

* RLC Workshop Papers (1/2):*
RL Beyond Rewards
rlbrew2-workshop.github.io

- Tue 11:59 (spotlight talk): Towards An Option Basis To Optimize All Rewards by S. Chandrasekar
- The World Is Bigger: A Computationally-Embedded Perspective on the Big World Hypothesis by A. Lewandowsi

8 months ago 0 0 1 0

Here's what our group will be presenting at RLC'25.

* Invited Talks at Workshops:*
Tue 10:00: The Causal RL Workshop sites.google.com/uci.edu/crlw...
Tue 14:30: Inductive Biases in RL (IBRL) Workshop
sites.google.com/view/ibrl-wo...
Tue 15:00: Panel Discussion at IBRL Workshop

8 months ago 0 0 1 0
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RLC starts tomorrow here in Edmonton. I couldn't be more excited! It has a fantastic roll of speakers, great papers, and workshops. And this time, it is in Edmonton ๐Ÿ˜

@rl-conference.bsky.social is my favourite conference, and no, it is not because I am one of its organizers this year.

8 months ago 12 3 0 0

This was a great long-term effort from @martinklissarov.bsky.social, Akhil Bagaria, and @ray-luo.bsky.social, and it led to a great overview of the ideas behind leveraging temporal abstractions in AI.

If anything, I think this is very useful resource for anyone interested in this field!

9 months ago 7 1 0 0

To align better with workshop acceptance dates, ๐‘๐‹๐‚ ๐ข๐ฌ ๐ž๐ฑ๐ญ๐ž๐ง๐๐ข๐ง๐  ๐ข๐ญ๐ฌ ๐ž๐š๐ซ๐ฅ๐ฒ ๐ซ๐ž๐ ๐ข๐ฌ๐ญ๐ซ๐š๐ญ๐ข๐จ๐ง ๐๐ž๐š๐๐ฅ๐ข๐ง๐ž ๐ญ๐จ ๐‰๐ฎ๐ง๐ž ๐Ÿ๐Ÿ‘๐ซ๐!

10 months ago 8 3 0 1
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9/9: I genuinely think AgarCL might unlock new research avenues in CRL, including loss of plasticity, exploration, representation learning, and more. I do hope you consider using it.

Repo: github.com/machado-rese...
Website: agarcl.github.io
Preprint: arxiv.org/abs/2505.18347

10 months ago 6 0 0 0
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8/9: Well, if you are still interested, you should probably consider reading the paper, but it is interesting to see that most of the agents we considered were able to reach human-level performance only in the most benign settings. And we did use a lot of computing here!

10 months ago 4 1 1 0
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7/9: Through mini-games, we tried to quantify and isolate some of the challenges AgarCL poses, including partial observability, non-stationarity, exploration, hyperparameter tuning, and the non-episodic nature of the environment (so easy to forget!). Where do our agents "break"?

10 months ago 1 0 1 0
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6/9: Importantly, this is a challenge problem that forces us to deal with many problems we often avoid, such as hyperparameter sweeps and exploration in CRL.

It is perhaps no surprise that the classic algorithms we considered couldn't really make much progress in the full game.

10 months ago 2 0 1 0
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5/9: Over time, even the agent's observation will change, as the camera needs to zoom out to accommodate more agents; not to mention that there are other agents in the environment. I'm very excited about AgarCL because I think it allows us to ask questions we couldn't before.

10 months ago 2 0 1 0
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4/9: AgarCL is an adaptation of agar.io, a game with simple mechanics that lead to complex interactions. It's non-episodic, and a key aspect is that the agent dynamics change as it accumulates mass: It becomes slower, gains new affordances, sheds more mass, etc.

10 months ago 3 0 1 1