Clone this repo:

https://github.com/divilian/IPD-LLM

and run the program as follows (for instance):

$ python cli.py 150 \
    --agent-fracs TitForTat 0.3 Mean 0.3 Sucker 0.4 \
    --p-same 0.1 --p-diff 0.01 \
    --num-iter 100 --plot

You can run “python cli.py -h“, too, to see all the command line arguments and what they mean.

Bonus points to anyone who can vary the parameters such that (1) they maintain at least 5% of all three non-LLM agent types (Mean, Sucker, and TitForTat), and (2) the TitForTat agents, on average, come out the winners.

Quiz #5 has been posted to Canvas, and is due as the month of March expires. It’s timed at 60 minutes and otherwise has all the normal rules. Good luck!

You guys did a really good job of remembering each others’ names. Clearly this was the wrong bar to set for creating an edge in our class graph, because the thing is super dense (click to enlarge):

I’d like to get a more meaningful graph for analysis. So, since I’m giving away XP like candy, here’s another way to earn an additional +1XP: send me an email with subject line “DATA 420 class graph” that has the first name of every student in the class that you can remember having a conversation with. It might have been a one-on-one conversation, or a group conversation in which you and the other student were both present.

The conversation can be of any length. For instance, this counts as “a conversation”:

Them: Yo.
You: S’up.

(If you’ve never had a conversation with anyone else in the class, that’s fine; you can just say “nobody” in your email.)

I’m expecting that with this new, higher bar for edges, most students will have a degree of between 0 and 8, instead of this craziness:

If you’re interested in pursuing a masters degree at Virginia Tech, consider checking out this information session about the program.

I’ve now posted the reflection paper assignment I promised, and I hope many of you will consider completing it. It’s due in a month, so this should give you plenty of time to get your creative juices flowing and to digest many things that are in the book.

One word of warning: grading for this paper will be rigorous. I am not looking for two pages of crap, or for two pages of a stream of consciousness. If you turn in crap, expect to get 5 or 10 XP for your grade, depending on the level of crap. To get a score more towards the maximum, I’m looking for excellence. Take pride in your work, give yourself enough time to succeed, and bounce ideas off myself or others, and you should be well-positioned.

Homework #4 is posted, and is due next week. There will be no extensions to this one, so don’t expect one. Time to get started!

Click for a close-up!

What do people think Samuel is doing in the picture? Here are the results:

I’ve pushed the schelling.py program from today to the class github repo, as well as proof for Olivia that yes, Thomas Schelling’s name really does have a ‘c’ in it.

Quiz #4 contained multiple brain farts by yours truly, and so for a couple of the questions you may see your answer raised. In particular, my logical thinking failed me in numerous ways on the last problem, so I have given everyone the full 6 points for this question. I’ll explain in more detail in class today.

Be advised that at least one of the answers to quiz #4 is incorrect. I will fix that and make amends as soon as I can get to it. In the meantime, don’t freak out about it, and just wait patiently for a correction.

Since campus is closed tomorrow, homework #3 will be due Tuesday, March 17th at 5pm instead of tomorrow.

Due to the campus closure, office hours will be on Zoom tomorrow at the usual time. The Canvas announcements have the Zoom link, which is the same as it’s always been for this class.

Quiz #4 has been posted to Canvas. It is timed at 60 minutes, and is closed-all-the-usual-stuff. Although it is due on Wed, Mar 18th at midnight, it only covers class material up through this past week. So you can take it any time!

Good luck!

The code from today’s class has been pushed to the class github repo. (sirabm.py).

I’ve decided to postpone homework #3‘s due date from Friday to Monday, March 16th. That way I can expect excellent work!

I will be holding Office Hours virtually (over Zoom) today, at the usual time (12-2pm). See the Canvas page for the Zoom link (which is the same Zoom link as always).

I’ve posted my solutions to the reading check I meant to give on Thursday (but wasn’t ready in time) to the readings tab. Check out what you missed — all two pages!! :-O

I’ve posted a couple new entries on the Readings page (click “Readings” on the menu bar above) that you will want to have completed on time. There probably won’t be a reading check on these (though I’m mulling over writing one) but you absolutely need this background information by the dates specified.

So, a little light reading over spring break for you, or some stuff to dig into as soon as you get back.

Cheers!

The code from yesterday’s class has been pushed to the github repo:

• bol.py (using the mean-field assumption)
• bol_grid.py (the version with a 2d grid space)

Quiz #3 has been posted to Canvas. It contains nothing about the Agent-Based Modeling we began yesterday, and hence is completely safe for you to take now. I personally would recommend not waiting all the way to March 10th to take it, but I made that the due date in the spirit of flexibility.

Homework #3 has been posted, and is due at 5pm the Friday after spring break. It will be submitted physically (like, actual paper) not electronically.

Should you work on this over spring break? Yeah, duh! (Or you don’t have to, but DO NOT procrastinate once classes resume.)

If you’d like to cash in your XP cards mid-semester, there will be one opportunity to do so: Thursday’s class (2/26). To redeem these, your XP cash must be:

• Stapled together with a staple, using a stapler.
• Have your name clearly printed on the back of the bottom-most card in the stack.
• Have the sum total of the XP also written on the back of the bottom-most card (so I don’t have to count).

You may hand me your stapled (using a stapler) stack of cards on Thursday, and I will put your points up on the scoreboard over spring break. If you don’t do this on Thursday, there is no penalty; you can just hold on to your cards until the final exam, and turn them all in then.

I’m going to see a specialist tomorrow morning about my back pain, and so might be late to my office hours. I’ll get there as soon as I can!

It’s come to my attention that there’s a bug in the answers to the Wild West problem on quiz #2. I owe everybody +2XP as a result. So fear not if you get one of the answers wrong there — you will be compensated.

FYI, I’ve finally updated the notes (see “Notes” tab on menu above) to reflect our content through today.

For anyone interested in more details about Trump’s firing of Erika McEntarfer, the director of the Bureau of Labor Statistics (BLS), after the BLS produced their monthly job report that he didn’t like, here are some sources.

• https://apnews.com/article/trump-jobs-firing-f00e9bf96d0110519be9bf4f3ec89195
• https://www.govexec.com/management/2025/08/after-firing-bls-chief-lutnick-tells-federal-statisticians-independence-nonsense/407404/
• https://fortune.com/2025/11/13/october-2025-jobs-inflation-data-release-government-shutdown/

Today’s class will feature reading check #8 (on Silver chapter 6) as scheduled. However, the reading check #9 (on Silver chapter 7) will be postponed from the originally scheduled Thu Feb. 19th until Tue Feb. 24th.

This has been a public service announcement.

Quiz #2 has been posted to Canvas, and is due this Friday at midnight. It is open-book, open-notes, closed-other-humans, closed-AI, closed-Python, and timed at one hour. Good luck!

Homework #2 has been posted, and is due a week from Friday. Happy hunting!

I’ve pushed the code from class on Thursday to the git repo:

• lotka_volterra.py — the Lotka-Volterra (predator-prey) simulation
• furnace2.py — the parameter-sweep version of the furnace simulation

I’ve posted the temperature model we did in class today to the class github repo.

Unlike Tuesday’s reading check, quite a few people missed at least a question or two on yesterday’s, so you might want to take a look at the solution I just posted on the readings page. Also: next week’s checks will cover Silver chapters 4 and 5.