YY Ahn
@yyahn.bsky.social
Prof @ School of Data Science, University of Virginia. Formerly at IU. Networks, data science, and machine learning. https://yyahn.com
🚲🚲🚲
🚲🚲🚲
I see the point of the commentary but am not so sure about these examples... Isn't the PCA doing what it's supposed to do in these examples? (I often use "finding the most informative perspective to look at a fish" as an intuitive way to understand PCA.)
www.pnas.org/doi/10.1073/...
www.pnas.org/doi/10.1073/...
November 16, 2025 at 12:35 AM
I see the point of the commentary but am not so sure about these examples... Isn't the PCA doing what it's supposed to do in these examples? (I often use "finding the most informative perspective to look at a fish" as an intuitive way to understand PCA.)
www.pnas.org/doi/10.1073/...
www.pnas.org/doi/10.1073/...
The system has just been turned on. This is so awesome to see! ☀️☀️☀️
October 24, 2025 at 2:50 PM
The system has just been turned on. This is so awesome to see! ☀️☀️☀️
I'm excited to give a talk tomorrow at the Organizational Behavior Seminar series at the Stanford Graduate School of Business about modeling interconnected human beliefs. See you soon!
www.gsb.stanford.edu/faculty-rese...
www.gsb.stanford.edu/faculty-rese...
October 14, 2025 at 10:30 PM
I'm excited to give a talk tomorrow at the Organizational Behavior Seminar series at the Stanford Graduate School of Business about modeling interconnected human beliefs. See you soon!
www.gsb.stanford.edu/faculty-rese...
www.gsb.stanford.edu/faculty-rese...
c-ville.com/car-light-fa... A nice article by @nathanalderman.com! It's awesome to see so many people biking in Charlottesville *despite of* pretty terrible infrastructure (@cvillecityhall.bsky.social 👀)
It reminds me of an old tweet that I can't agree more.
It reminds me of an old tweet that I can't agree more.
September 24, 2025 at 9:07 PM
c-ville.com/car-light-fa... A nice article by @nathanalderman.com! It's awesome to see so many people biking in Charlottesville *despite of* pretty terrible infrastructure (@cvillecityhall.bsky.social 👀)
It reminds me of an old tweet that I can't agree more.
It reminds me of an old tweet that I can't agree more.
I've moved!
❤️ → 🧡💙
"Hoosiers" - "sier"
B → C & town → ville
... And the “smaller and smaller cities” streak lives on. Grateful for IU colleagues ❤️ and excited for new adventures at UVA School of Data Science, aka the "school without walls"! 🧡💙
❤️ → 🧡💙
"Hoosiers" - "sier"
B → C & town → ville
... And the “smaller and smaller cities” streak lives on. Grateful for IU colleagues ❤️ and excited for new adventures at UVA School of Data Science, aka the "school without walls"! 🧡💙
August 15, 2025 at 8:50 PM
I've moved!
❤️ → 🧡💙
"Hoosiers" - "sier"
B → C & town → ville
... And the “smaller and smaller cities” streak lives on. Grateful for IU colleagues ❤️ and excited for new adventures at UVA School of Data Science, aka the "school without walls"! 🧡💙
❤️ → 🧡💙
"Hoosiers" - "sier"
B → C & town → ville
... And the “smaller and smaller cities” streak lives on. Grateful for IU colleagues ❤️ and excited for new adventures at UVA School of Data Science, aka the "school without walls"! 🧡💙
At Sunrise school (Charlottesville), but it's nothing special about this school, the parking lot and drop-off zone sprawl across as much space as the school itself. Yet, bike racks are in short supply and all the cars make it feel unsafe. If we want kids to walk/bike, we need to make it possible.
August 15, 2025 at 7:26 PM
At Sunrise school (Charlottesville), but it's nothing special about this school, the parking lot and drop-off zone sprawl across as much space as the school itself. Yet, bike racks are in short supply and all the cars make it feel unsafe. If we want kids to walk/bike, we need to make it possible.
🧪👋 I'm excited to join the standing committee on advancing science communication at the National Academies.
Question for the hive mind: What concrete actions or “infrastructure” would most strengthen science communication right now? Where should our committee focus its efforts?
Question for the hive mind: What concrete actions or “infrastructure” would most strengthen science communication right now? Where should our committee focus its efforts?
July 22, 2025 at 8:41 PM
🧪👋 I'm excited to join the standing committee on advancing science communication at the National Academies.
Question for the hive mind: What concrete actions or “infrastructure” would most strengthen science communication right now? Where should our committee focus its efforts?
Question for the hive mind: What concrete actions or “infrastructure” would most strengthen science communication right now? Where should our committee focus its efforts?
The emergence of eukaryotes as an evolutionary algorithmic phase transition
www.pnas.org/doi/10.1073/...
"... was due to an algorithmic phase transition equivalent to that of certain search algorithms triggered by the constraints in finding increasingly larger proteins."
A cool data collapse.
www.pnas.org/doi/10.1073/...
"... was due to an algorithmic phase transition equivalent to that of certain search algorithms triggered by the constraints in finding increasingly larger proteins."
A cool data collapse.
April 28, 2025 at 12:49 PM
The emergence of eukaryotes as an evolutionary algorithmic phase transition
www.pnas.org/doi/10.1073/...
"... was due to an algorithmic phase transition equivalent to that of certain search algorithms triggered by the constraints in finding increasingly larger proteins."
A cool data collapse.
www.pnas.org/doi/10.1073/...
"... was due to an algorithmic phase transition equivalent to that of certain search algorithms triggered by the constraints in finding increasingly larger proteins."
A cool data collapse.
A simple Keyboard Maestro script to change arxiv.org/pdf/xxxx to arxiv.org/abs/xxxx
I should have set this up years ago... 🥲
I should have set this up years ago... 🥲
April 24, 2025 at 5:51 PM
A simple Keyboard Maestro script to change arxiv.org/pdf/xxxx to arxiv.org/abs/xxxx
I should have set this up years ago... 🥲
I should have set this up years ago... 🥲
The *current* reinforcement learning methods may not be improving reasoning capacity of the LLMs. Instead, they may be training the models to find the shortcuts more efficiently.
limit-of-rlvr.github.io
limit-of-rlvr.github.io
April 23, 2025 at 1:40 PM
The *current* reinforcement learning methods may not be improving reasoning capacity of the LLMs. Instead, they may be training the models to find the shortcuts more efficiently.
limit-of-rlvr.github.io
limit-of-rlvr.github.io
arxiv.org/abs/2412.10924 - Tokens, the oft-overlooked appetizer: Large language models, the distributional hypothesis, and meaning. by Julia Witte Zimmerman et al. from 1Computational Story Lab at UVM
Super fun figures!
Super fun figures!
December 28, 2024 at 8:28 PM
arxiv.org/abs/2412.10924 - Tokens, the oft-overlooked appetizer: Large language models, the distributional hypothesis, and meaning. by Julia Witte Zimmerman et al. from 1Computational Story Lab at UVM
Super fun figures!
Super fun figures!
I think mass protests in Korea that draw millions always have strong festive elements. The song in the video: Han Chul Lee's "superstar": www.youtube.com/watch?v=N7gs...
"괜찮아 잘될 거야
너에겐 눈부신 미래가 있어"
“It’s okay, everything will work out.
You have a brilliant future ahead of you.”
"괜찮아 잘될 거야
너에겐 눈부신 미래가 있어"
“It’s okay, everything will work out.
You have a brilliant future ahead of you.”
December 14, 2024 at 11:13 AM
I think mass protests in Korea that draw millions always have strong festive elements. The song in the video: Han Chul Lee's "superstar": www.youtube.com/watch?v=N7gs...
"괜찮아 잘될 거야
너에겐 눈부신 미래가 있어"
“It’s okay, everything will work out.
You have a brilliant future ahead of you.”
"괜찮아 잘될 거야
너에겐 눈부신 미래가 있어"
“It’s okay, everything will work out.
You have a brilliant future ahead of you.”
"시위도 밥먹고" (Even protesters need to eat) crowd-sourced map for protest in Korea. Many volunteered to "pre-buy" thousands of drinks and other food items around the protest site so that protesters can eat/drink for free & the shops are supported during the protest. (+ restroom info)
www.torchmap.kr
www.torchmap.kr
December 14, 2024 at 10:35 AM
"시위도 밥먹고" (Even protesters need to eat) crowd-sourced map for protest in Korea. Many volunteered to "pre-buy" thousands of drinks and other food items around the protest site so that protesters can eat/drink for free & the shops are supported during the protest. (+ restroom info)
www.torchmap.kr
www.torchmap.kr
For most of winter, handlebar mitts (pogies) and a skullcap (beanie) inside your helmet is all you need to bike around. #wintercycling is not a rocket science and you can bike outside if you can walk outside.
December 7, 2024 at 12:23 AM
For most of winter, handlebar mitts (pogies) and a skullcap (beanie) inside your helmet is all you need to bike around. #wintercycling is not a rocket science and you can bike outside if you can walk outside.
It seems like the "strawberry" model is here.
openai.com/index/introd...
It has been a pleasure everyone 🥲
openai.com/index/introd...
It has been a pleasure everyone 🥲
September 12, 2024 at 8:24 PM
It seems like the "strawberry" model is here.
openai.com/index/introd...
It has been a pleasure everyone 🥲
openai.com/index/introd...
It has been a pleasure everyone 🥲
Hey I made a visualization of
the proposed Elon Musk pay package.
yyahn.com/elon_paypack...
Let me know what you think! 🙈 You can also suggest improvements: github.com/yy/elon_payp...
the proposed Elon Musk pay package.
yyahn.com/elon_paypack...
Let me know what you think! 🙈 You can also suggest improvements: github.com/yy/elon_payp...
June 9, 2024 at 10:29 PM
Hey I made a visualization of
the proposed Elon Musk pay package.
yyahn.com/elon_paypack...
Let me know what you think! 🙈 You can also suggest improvements: github.com/yy/elon_payp...
the proposed Elon Musk pay package.
yyahn.com/elon_paypack...
Let me know what you think! 🙈 You can also suggest improvements: github.com/yy/elon_payp...
The model gives us an intuitive way to think about simple v. complex contagion as well as vulnerability to mis/disinfo.
When the existing belief system is "primed" to accept a certain belief, it can spread virally; when it conflicts with existing beliefs, social reinforcement is critical.
🧵8/
When the existing belief system is "primed" to accept a certain belief, it can spread virally; when it conflicts with existing beliefs, social reinforcement is critical.
🧵8/
April 15, 2024 at 3:36 PM
The model gives us an intuitive way to think about simple v. complex contagion as well as vulnerability to mis/disinfo.
When the existing belief system is "primed" to accept a certain belief, it can spread virally; when it conflicts with existing beliefs, social reinforcement is critical.
🧵8/
When the existing belief system is "primed" to accept a certain belief, it can spread virally; when it conflicts with existing beliefs, social reinforcement is critical.
🧵8/
This model can also reproduce the optimal modularity phenomenon. When the new belief is going against the existing belief system, the clustering matters more and there is an optimal amount of clustering that can spread the information best.
🧵8/
🧵8/
April 15, 2024 at 3:32 PM
This model can also reproduce the optimal modularity phenomenon. When the new belief is going against the existing belief system, the clustering matters more and there is an optimal amount of clustering that can spread the information best.
🧵8/
🧵8/
It is also possible to reproduce the famous experiment by Damon Centola.
When we have the "simple" configuration, it spreads better in a random network than a clustered "large world"; when we have the "complex" setting, it spreads better in the clustered large-world than a small-world!
🧵8/
When we have the "simple" configuration, it spreads better in a random network than a clustered "large world"; when we have the "complex" setting, it spreads better in the clustered large-world than a small-world!
🧵8/
April 15, 2024 at 3:30 PM
It is also possible to reproduce the famous experiment by Damon Centola.
When we have the "simple" configuration, it spreads better in a random network than a clustered "large world"; when we have the "complex" setting, it spreads better in the clustered large-world than a small-world!
🧵8/
When we have the "simple" configuration, it spreads better in a random network than a clustered "large world"; when we have the "complex" setting, it spreads better in the clustered large-world than a small-world!
🧵8/
But, if new belief would disrupt a stable belief network, it will be difficult to be adopted.
So, with belief weights, depending on the relationship between the new belief and the existing beliefs, the model exhibits two distinct dynamics: simple & complex contagion!
🧵7/
So, with belief weights, depending on the relationship between the new belief and the existing beliefs, the model exhibits two distinct dynamics: simple & complex contagion!
🧵7/
April 15, 2024 at 3:27 PM
But, if new belief would disrupt a stable belief network, it will be difficult to be adopted.
So, with belief weights, depending on the relationship between the new belief and the existing beliefs, the model exhibits two distinct dynamics: simple & complex contagion!
🧵7/
So, with belief weights, depending on the relationship between the new belief and the existing beliefs, the model exhibits two distinct dynamics: simple & complex contagion!
🧵7/
We (w Nathaniel Rodriguez & Johan Bollen) introduced a simple model of belief interaction network in 2016: journals.plos.org/plosone/arti...
In this model, beliefs are signed edges connecting concepts, which lead to the belief interaction via social balance condition. Another point was that ..
🧵3/
In this model, beliefs are signed edges connecting concepts, which lead to the belief interaction via social balance condition. Another point was that ..
🧵3/
April 15, 2024 at 3:14 PM
We (w Nathaniel Rodriguez & Johan Bollen) introduced a simple model of belief interaction network in 2016: journals.plos.org/plosone/arti...
In this model, beliefs are signed edges connecting concepts, which lead to the belief interaction via social balance condition. Another point was that ..
🧵3/
In this model, beliefs are signed edges connecting concepts, which lead to the belief interaction via social balance condition. Another point was that ..
🧵3/
Check out our new paper about belief & contagion dynamics led by Rachith Aiyappa!
We show that both simple and complex contagion dynamics can emerge from a model of belief interaction network.
In other words, simple/complex contagions may be just two sides of the underlying belief dynamics. 🧵1/
We show that both simple and complex contagion dynamics can emerge from a model of belief interaction network.
In other words, simple/complex contagions may be just two sides of the underlying belief dynamics. 🧵1/
April 15, 2024 at 3:05 PM
Check out our new paper about belief & contagion dynamics led by Rachith Aiyappa!
We show that both simple and complex contagion dynamics can emerge from a model of belief interaction network.
In other words, simple/complex contagions may be just two sides of the underlying belief dynamics. 🧵1/
We show that both simple and complex contagion dynamics can emerge from a model of belief interaction network.
In other words, simple/complex contagions may be just two sides of the underlying belief dynamics. 🧵1/
This study estimated AI-usage in AI conference reviews not by trying to "detect" AI-written documents but by estimating the usage at the level of the whole corpus, with a convincing validation.
Not a surprise: AI researchers are using GPT for reviews.
arxiv.org/abs/2403.07183
("commendable" 😂)
Not a surprise: AI researchers are using GPT for reviews.
arxiv.org/abs/2403.07183
("commendable" 😂)
March 19, 2024 at 2:58 PM
This study estimated AI-usage in AI conference reviews not by trying to "detect" AI-written documents but by estimating the usage at the level of the whole corpus, with a convincing validation.
Not a surprise: AI researchers are using GPT for reviews.
arxiv.org/abs/2403.07183
("commendable" 😂)
Not a surprise: AI researchers are using GPT for reviews.
arxiv.org/abs/2403.07183
("commendable" 😂)
A paper led by @dakotamurray.bsky.social Jisung Yoon, Sadamori Kojaku (and with Rodrigo Costas @wsjung.bsky.social, and Staša Milojević) in PNAS!
📖+🤖 → 🌌
✈️🚊🚲🚶+🤖→🌌
Paper: www.pnas.org/doi/10.1073/...
1/
📖+🤖 → 🌌
✈️🚊🚲🚶+🤖→🌌
Paper: www.pnas.org/doi/10.1073/...
1/
December 27, 2023 at 12:23 AM
A paper led by @dakotamurray.bsky.social Jisung Yoon, Sadamori Kojaku (and with Rodrigo Costas @wsjung.bsky.social, and Staša Milojević) in PNAS!
📖+🤖 → 🌌
✈️🚊🚲🚶+🤖→🌌
Paper: www.pnas.org/doi/10.1073/...
1/
📖+🤖 → 🌌
✈️🚊🚲🚶+🤖→🌌
Paper: www.pnas.org/doi/10.1073/...
1/