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
🚲🚲🚲
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"Confessions of a recovering engineer" by Chuck Marohn (@strongtowns.org) viscerally captures the chasm between the "metrics" that drive engineering projects and what most people consider critical and important.
www.amazon.com/Confessions-...
www.amazon.com/Confessions-...
January 1, 2026 at 9:37 PM
"Confessions of a recovering engineer" by Chuck Marohn (@strongtowns.org) viscerally captures the chasm between the "metrics" that drive engineering projects and what most people consider critical and important.
www.amazon.com/Confessions-...
www.amazon.com/Confessions-...
Python environment setup: yyahn.com/wiki/Python/...
1. I'm trying to use uv as much as possible.
2. use direnv!
3. Set ruff once and then never worry about code formatting.
1. I'm trying to use uv as much as possible.
2. use direnv!
3. Set ruff once and then never worry about code formatting.
Python environment setup
Modern Python environment setup using uv. The problem Python's dependency management has historically been messy. Projects need: 1. Isolation — different...
yyahn.com
January 1, 2026 at 7:13 PM
Python environment setup: yyahn.com/wiki/Python/...
1. I'm trying to use uv as much as possible.
2. use direnv!
3. Set ruff once and then never worry about code formatting.
1. I'm trying to use uv as much as possible.
2. use direnv!
3. Set ruff once and then never worry about code formatting.
I've updated my project template repo: github.com/yy/project-t...
It's a public template that you can use to initialize a new research project repo.
It's a public template that you can use to initialize a new research project repo.
GitHub - yy/project-template: A template for research repositories
A template for research repositories. Contribute to yy/project-template development by creating an account on GitHub.
github.com
January 1, 2026 at 7:08 PM
I've updated my project template repo: github.com/yy/project-t...
It's a public template that you can use to initialize a new research project repo.
It's a public template that you can use to initialize a new research project repo.
Some basic tips about Claude code: yyahn.com/wiki/Claude%...
Claude Code (CC)
Anthropic's AI coding agent. Settings The preferences and settings are stored in (at project root or in ) and for each project. The former contains natural...
yyahn.com
January 1, 2026 at 6:29 PM
Some basic tips about Claude code: yyahn.com/wiki/Claude%...
Reposted by YY Ahn
Incredibly, not one of these milestones scores as a “win” using the traffic engineering metrics that quietly dictate city planning.
Urban planning prof Jonathan Levine and I have one paper detailing why and another explaining why it has to change for any vision of abundance to succeed. Links below.
Urban planning prof Jonathan Levine and I have one paper detailing why and another explaining why it has to change for any vision of abundance to succeed. Links below.
Year 1 data on congestion pricing in Manhattan…
* Vehicle traffic: -11%
* Foot traffic: +3.4%
* Storefront vacancy: -0.9%
* Pollution: -22%
* Revenue for mass transit: $548M
So YES this has been a huge success.
* Vehicle traffic: -11%
* Foot traffic: +3.4%
* Storefront vacancy: -0.9%
* Pollution: -22%
* Revenue for mass transit: $548M
So YES this has been a huge success.
December 30, 2025 at 4:54 PM
Incredibly, not one of these milestones scores as a “win” using the traffic engineering metrics that quietly dictate city planning.
Urban planning prof Jonathan Levine and I have one paper detailing why and another explaining why it has to change for any vision of abundance to succeed. Links below.
Urban planning prof Jonathan Levine and I have one paper detailing why and another explaining why it has to change for any vision of abundance to succeed. Links below.
Reposted by YY Ahn
In America, where irony is dead, a hotel chain uses a policy denying shelter to local people, for fear of accidentally housing homeless persons…
To deny a reservation to the author of a much-lauded book on how American economic unfairness forces working people into homelessness.
To deny a reservation to the author of a much-lauded book on how American economic unfairness forces working people into homelessness.
A Hampton Inn in Asheville just canceled my family's reservation because our address (incorrectly) showed Asheville—and the hotel bars locals within 50 miles.
When I asked why, they said, "because of our homeless population," adding that most hotels here have similar policies.
This is outrageous.
When I asked why, they said, "because of our homeless population," adding that most hotels here have similar policies.
This is outrageous.
December 29, 2025 at 2:46 AM
In America, where irony is dead, a hotel chain uses a policy denying shelter to local people, for fear of accidentally housing homeless persons…
To deny a reservation to the author of a much-lauded book on how American economic unfairness forces working people into homelessness.
To deny a reservation to the author of a much-lauded book on how American economic unfairness forces working people into homelessness.
"LLMs broadly align with human category boundaries, yet fall short on fine-grained semantic distinctions. Unlike humans, ... LLMs aggressively compress, achieving more optimal information-theoretic compression at the cost of semantic richness." arxiv.org/abs/2505.17117
From Tokens to Thoughts: How LLMs and Humans Trade Compression for Meaning
Humans organize knowledge into compact conceptual categories that balance compression with semantic richness. Large Language Models (LLMs) exhibit impressive linguistic abilities, but whether they nav...
arxiv.org
December 22, 2025 at 3:16 PM
"LLMs broadly align with human category boundaries, yet fall short on fine-grained semantic distinctions. Unlike humans, ... LLMs aggressively compress, achieving more optimal information-theoretic compression at the cost of semantic richness." arxiv.org/abs/2505.17117
Reposted by YY Ahn
We're hiring interns in the Computational Social Science group at Microsoft Research NYC!
If you're interested in designing AI‑based systems and understanding their impact at both individual and societal scales, apply here by Jan 9, 2026: apply.careers.microsoft.com/careers/job/...
If you're interested in designing AI‑based systems and understanding their impact at both individual and societal scales, apply here by Jan 9, 2026: apply.careers.microsoft.com/careers/job/...
Research Intern - Computational Social Science | Microsoft Careers
Research Interns put inquiry and theory into practice. Alongside fellow doctoral candidates and some of the world's best researchers, Research Interns learn, collaborate, and network for life. Researc...
apply.careers.microsoft.com
December 15, 2025 at 4:33 PM
We're hiring interns in the Computational Social Science group at Microsoft Research NYC!
If you're interested in designing AI‑based systems and understanding their impact at both individual and societal scales, apply here by Jan 9, 2026: apply.careers.microsoft.com/careers/job/...
If you're interested in designing AI‑based systems and understanding their impact at both individual and societal scales, apply here by Jan 9, 2026: apply.careers.microsoft.com/careers/job/...
Reposted by YY Ahn
You can’t “fix” X, The Everything App by going back and posting there because the owner has this thumb on the scale of the algorithm to promote the worst ideas and people. It’s not a viable solution, you have to let it go.
Dear Bluesky liberals. Come back to Twitter. Please. PLEASE.
December 14, 2025 at 11:59 PM
You can’t “fix” X, The Everything App by going back and posting there because the owner has this thumb on the scale of the algorithm to promote the worst ideas and people. It’s not a viable solution, you have to let it go.
I always thought that the language mixing during reasoning is fascinating and whether it's actually a way that LLMs optimize its reasoning. Just came across a study on this: arxiv.org/abs/2507.15849
The Impact of Language Mixing on Bilingual LLM Reasoning
Proficient multilingual speakers often intentionally switch languages in the middle of a conversation. Similarly, recent reasoning-focused bilingual large language models (LLMs) with strong capabiliti...
arxiv.org
December 14, 2025 at 4:52 PM
I always thought that the language mixing during reasoning is fascinating and whether it's actually a way that LLMs optimize its reasoning. Just came across a study on this: arxiv.org/abs/2507.15849
This experiment can produce interesting data...
Announcing the ICML 2026 policy for LLMs in reviewing! Reviewers and authors both pick either conservative or permissive LLM use, and will be matched accordingly. Importantly: authors on papers who choose conservative must obey the conservative policy as reviewers.
December 12, 2025 at 3:00 PM
This experiment can produce interesting data...
Reposted by YY Ahn
Announcing the ICML 2026 policy for LLMs in reviewing! Reviewers and authors both pick either conservative or permissive LLM use, and will be matched accordingly. Importantly: authors on papers who choose conservative must obey the conservative policy as reviewers.
December 11, 2025 at 3:59 PM
Announcing the ICML 2026 policy for LLMs in reviewing! Reviewers and authors both pick either conservative or permissive LLM use, and will be matched accordingly. Importantly: authors on papers who choose conservative must obey the conservative policy as reviewers.
Reposted by YY Ahn
New paper out in @science.org! We unveil the online manipulation market with the Cambridge Online Trust & Safety Index (COTSI). We show in real time the cost of purchasing fake accounts across every social platform around the world - so they can be held accountable
www.science.org/doi/10.1126/...
www.science.org/doi/10.1126/...
Mapping the online manipulation economy
A market perspective on digital manipulation may help improve online trust and safety
www.science.org
December 11, 2025 at 7:05 PM
New paper out in @science.org! We unveil the online manipulation market with the Cambridge Online Trust & Safety Index (COTSI). We show in real time the cost of purchasing fake accounts across every social platform around the world - so they can be held accountable
www.science.org/doi/10.1126/...
www.science.org/doi/10.1126/...
"it is possible for machines to discover a state-of-the-art RL rule that outperforms manually designed rules. This was achieved by meta-learning from the cumulative experiences of a population of agents across a large number of complex environments."
www.nature.com/articles/s41...
www.nature.com/articles/s41...
Discovering state-of-the-art reinforcement learning algorithms - Nature
An autonomous method discovers reinforcement learning rules from the cumulative experiences of a population of agents across a large number of complex environments, and the discovered rule achieves st...
www.nature.com
December 11, 2025 at 8:47 PM
"it is possible for machines to discover a state-of-the-art RL rule that outperforms manually designed rules. This was achieved by meta-learning from the cumulative experiences of a population of agents across a large number of complex environments."
www.nature.com/articles/s41...
www.nature.com/articles/s41...
Reposted by YY Ahn
A wonderful opportunity to come join the @uvadatascience.bsky.social community!!
🚨 A research staff position at my group at @uvadatascience.bsky.social!
I’m recruiting a research Scientist (or postdoc scholar). You can apply here! bit.ly/ylab-researc...
For more information: www.linkedin.com/feed/update/...
Inquiries: yyahn@virginia.edu with [job] in the subject line.
I’m recruiting a research Scientist (or postdoc scholar). You can apply here! bit.ly/ylab-researc...
For more information: www.linkedin.com/feed/update/...
Inquiries: yyahn@virginia.edu with [job] in the subject line.
Research Scientist or Postdoctoral Research Associate - School of Data Science
The School of Data Science at the University of Virginia and Professor Yong-Yeol (“YY”) Ahn, Quantitative Foundation Distinguished Professor, are excited to announce two professional research staff po...
bit.ly
December 10, 2025 at 9:39 PM
A wonderful opportunity to come join the @uvadatascience.bsky.social community!!
🚨 A research staff position at my group at @uvadatascience.bsky.social!
I’m recruiting a research Scientist (or postdoc scholar). You can apply here! bit.ly/ylab-researc...
For more information: www.linkedin.com/feed/update/...
Inquiries: yyahn@virginia.edu with [job] in the subject line.
I’m recruiting a research Scientist (or postdoc scholar). You can apply here! bit.ly/ylab-researc...
For more information: www.linkedin.com/feed/update/...
Inquiries: yyahn@virginia.edu with [job] in the subject line.
Research Scientist or Postdoctoral Research Associate - School of Data Science
The School of Data Science at the University of Virginia and Professor Yong-Yeol (“YY”) Ahn, Quantitative Foundation Distinguished Professor, are excited to announce two professional research staff po...
bit.ly
December 10, 2025 at 6:26 PM
🚨 A research staff position at my group at @uvadatascience.bsky.social!
I’m recruiting a research Scientist (or postdoc scholar). You can apply here! bit.ly/ylab-researc...
For more information: www.linkedin.com/feed/update/...
Inquiries: yyahn@virginia.edu with [job] in the subject line.
I’m recruiting a research Scientist (or postdoc scholar). You can apply here! bit.ly/ylab-researc...
For more information: www.linkedin.com/feed/update/...
Inquiries: yyahn@virginia.edu with [job] in the subject line.
Reposted by YY Ahn
The incredible @yyahn.bsky.social is building something special at UVA.
🚨 If you're a fit for this job, I highly recommend applying!
Find more details via the link below.
www.linkedin.com/posts/yyahn_...
🚨 If you're a fit for this job, I highly recommend applying!
Find more details via the link below.
www.linkedin.com/posts/yyahn_...
December 10, 2025 at 6:01 PM
The incredible @yyahn.bsky.social is building something special at UVA.
🚨 If you're a fit for this job, I highly recommend applying!
Find more details via the link below.
www.linkedin.com/posts/yyahn_...
🚨 If you're a fit for this job, I highly recommend applying!
Find more details via the link below.
www.linkedin.com/posts/yyahn_...
"What?" was my first reaction, but maybe this is *roughly* the right direction in a world where 'generation' becomes ever cheaper while 'evaluation' remains difficult.
But financial incentives may also attract more AI review slops. Will they be able to reliably root out AI review slops?
But financial incentives may also attract more AI review slops. Will they be able to reliably root out AI review slops?
IJCAI 2026 will charge $100 USD per submission. Funds will be used to compensate reviewers.
2026.ijcai.org/ijcai-ecai-2...
2026.ijcai.org/ijcai-ecai-2...
December 9, 2025 at 7:22 PM
"What?" was my first reaction, but maybe this is *roughly* the right direction in a world where 'generation' becomes ever cheaper while 'evaluation' remains difficult.
But financial incentives may also attract more AI review slops. Will they be able to reliably root out AI review slops?
But financial incentives may also attract more AI review slops. Will they be able to reliably root out AI review slops?
@cvillecityhall.bsky.social is on track to miss its own comprehensive plan & climate goals while budgeting so little for bike infra due to failure to identify projects.
I wrote a letter urging Council to fund a connected, protected network—not another decade of failure
yyahn.com/wiki/article...
I wrote a letter urging Council to fund a connected, protected network—not another decade of failure
yyahn.com/wiki/article...
A letter to city council: Inability to execute is not a justification for inaction - YY Ahn
yyahn.com
December 9, 2025 at 3:07 PM
@cvillecityhall.bsky.social is on track to miss its own comprehensive plan & climate goals while budgeting so little for bike infra due to failure to identify projects.
I wrote a letter urging Council to fund a connected, protected network—not another decade of failure
yyahn.com/wiki/article...
I wrote a letter urging Council to fund a connected, protected network—not another decade of failure
yyahn.com/wiki/article...
Reposted by YY Ahn
Support Techdirt’s Uncompromising Coverage, Get Our First Commemorative Coin
If you've been following along, you know why independent voices matter right now. The administration has been attacking institutions left and right. News orgs, law firms, philanthropic funders, universities, you name it.…
If you've been following along, you know why independent voices matter right now. The administration has been attacking institutions left and right. News orgs, law firms, philanthropic funders, universities, you name it.…
Support Techdirt’s Uncompromising Coverage, Get Our First Commemorative Coin
If you've been following along, you know why independent voices matter right now. The administration has been attacking institutions left and right. News orgs, law firms, philanthropic funders, universities, you name it. Many are capitulating. But not us. Someone needs to step up and keep doing this work without flinching and without compromising. That's where you come in.
www.techdirt.com
December 3, 2025 at 5:31 PM
Support Techdirt’s Uncompromising Coverage, Get Our First Commemorative Coin
If you've been following along, you know why independent voices matter right now. The administration has been attacking institutions left and right. News orgs, law firms, philanthropic funders, universities, you name it.…
If you've been following along, you know why independent voices matter right now. The administration has been attacking institutions left and right. News orgs, law firms, philanthropic funders, universities, you name it.…
Reposted by YY Ahn
Reposted by YY Ahn
⏰ 𝗗𝗲𝗮𝗱𝗹𝗶𝗻𝗲: 𝗗𝗲𝗰𝗲𝗺𝗯𝗲𝗿 𝟭𝟵!
NetSci 2026 abstract submissions close Dec 19 — just around the corner.
If you’re doing exciting work in network science (theory, computation, or applications), this is your chance to share it with a global community.
📅 Submit by Dec 19
🔗 www.netsci2026.com/call-for-abs...
NetSci 2026 abstract submissions close Dec 19 — just around the corner.
If you’re doing exciting work in network science (theory, computation, or applications), this is your chance to share it with a global community.
📅 Submit by Dec 19
🔗 www.netsci2026.com/call-for-abs...
December 1, 2025 at 3:59 PM
⏰ 𝗗𝗲𝗮𝗱𝗹𝗶𝗻𝗲: 𝗗𝗲𝗰𝗲𝗺𝗯𝗲𝗿 𝟭𝟵!
NetSci 2026 abstract submissions close Dec 19 — just around the corner.
If you’re doing exciting work in network science (theory, computation, or applications), this is your chance to share it with a global community.
📅 Submit by Dec 19
🔗 www.netsci2026.com/call-for-abs...
NetSci 2026 abstract submissions close Dec 19 — just around the corner.
If you’re doing exciting work in network science (theory, computation, or applications), this is your chance to share it with a global community.
📅 Submit by Dec 19
🔗 www.netsci2026.com/call-for-abs...
Reposted by YY Ahn
If anyone is curious about the current list of search terms being used by right wing activist organizations to harass university professors, here's a public records request I received today from Mike Howell of the Heritage Foundation. Not intimidating or meant to curtail by my speech at all, right?
August 6, 2025 at 10:03 PM
If anyone is curious about the current list of search terms being used by right wing activist organizations to harass university professors, here's a public records request I received today from Mike Howell of the Heritage Foundation. Not intimidating or meant to curtail by my speech at all, right?
I’m excited to speak at the 20th edition of @netsciconf.bsky.social! Honored to join speakers whose work I studied with fascination 20 years ago when I was just beginning. I’ll look forward to learning how the field has evolved, discovering new directions in network science, and meeting everyone!
✨ Excited to announce 𝗬𝗼𝗻𝗴-𝗬𝗲𝗼𝗹 (𝗬𝗬) 𝗔𝗵𝗻 as a NetSci 2026 Plenary Speaker! A leading network and data scientist, YY explores how complex systems shape behavior, cognition, and discovery. Stay tuned for more speaker updates as we build toward an inspiring NetSci 2026! ✨
www.netsci2026.com/speakers
www.netsci2026.com/speakers
December 1, 2025 at 4:59 PM
I’m excited to speak at the 20th edition of @netsciconf.bsky.social! Honored to join speakers whose work I studied with fascination 20 years ago when I was just beginning. I’ll look forward to learning how the field has evolved, discovering new directions in network science, and meeting everyone!
Reposted by YY Ahn
✨ Excited to announce 𝗬𝗼𝗻𝗴-𝗬𝗲𝗼𝗹 (𝗬𝗬) 𝗔𝗵𝗻 as a NetSci 2026 Plenary Speaker! A leading network and data scientist, YY explores how complex systems shape behavior, cognition, and discovery. Stay tuned for more speaker updates as we build toward an inspiring NetSci 2026! ✨
www.netsci2026.com/speakers
www.netsci2026.com/speakers
November 26, 2025 at 5:04 PM
✨ Excited to announce 𝗬𝗼𝗻𝗴-𝗬𝗲𝗼𝗹 (𝗬𝗬) 𝗔𝗵𝗻 as a NetSci 2026 Plenary Speaker! A leading network and data scientist, YY explores how complex systems shape behavior, cognition, and discovery. Stay tuned for more speaker updates as we build toward an inspiring NetSci 2026! ✨
www.netsci2026.com/speakers
www.netsci2026.com/speakers