"Bounded-Confidence Models of Opinion Dynamics with Adaptive Confidence Bounds"

Another of my papers just came out in final form. Here are some details.

Title: Bounded-Confidence Models of Opinion Dynamics with Adaptive Confidence Bounds

Authors: Grace J. Li, Jiajie Luo, and Mason A. Porter

Abstract: People's opinions change with time as they interact with each other. In a bounded-confidence model (BCM) of opinion dynamics, individuals (which are represented by the nodes of a network) have continuous-valued opinions and are influenced by neighboring nodes whose opinions are sufficiently similar to theirs (i.e., are within a confidence bound). In this paper, we formulate and analyze discrete-time BCMs with heterogeneous and adaptive confidence bounds. We introduce two new models: (1) a BCM with synchronous opinion updates that generalizes the Hegselmann–Krause model; and (2) a BCM with asynchronous opinion updates that generalizes the Deffuant–Weisbuch model. We analytically and numerically explore our adaptive-confidence BCMs' limiting behaviors, including the confidence-bound dynamics, the formation of clusters of nodes with similar opinions, and the time evolution of ``effective graphs,"" which are time-dependent subgraphs of networks with edges only between nodes that are receptive to each other. For a variety of networks and a wide range of values of the parameters that control the increase and decrease of confidence bounds, we demonstrate numerically that our adaptive-confidence BCMs result in fewer major opinion clusters and longer convergence times than the baseline (i.e., nonadaptive) BCMs. In our numerical simulations, we also observe that our adaptive-confidence BCMs can have adjacent nodes that converge to the same opinion but are not receptive to each other. This qualitative behavior does not occur in the associated baseline BCMs.

What Happens at the Global Physics Summit Stays at the Global Physics Summit

Later this afternoon, I will be taking a train to Anaheim to go to the Global Physics Summit, where I will be participating in the March-Meeting wing of this summit. I'll only be around for about a day and a half or so, but nevertheless I will be making my triumphant return to the March Meeting (which I last attended in 2016).

Update: I ended up just taking a Lyft directly to my hotel and not bothering with the train.

What Happens in the Research Triangle Stays in the Research Triangle (2025 Edition)

I am flying over to the Research Triangle in North Carolina to give talks at NC State and UNC Chapel Hill and also to talk shop with some of my collaborators.

“An “Opinion Reproduction Number” for Infodemics in a Bounded-Confidence Content-Spreading Process on Networks”

One of our papers was published in final form today. Here are some details.

Title: An “Opinion Reproduction Number” for Infodemics in a Bounded-Confidence Content-Spreading Process on Networks

Authors: Heather Z. Brooks and Mason A. Porter

Abstract: We study the spreading dynamics of content on networks. To do this, we use a model in which content spreads through a bounded-confidence mechanism. In a bounded-confidence model (BCM) of opinion dynamics, the agents of a network have continuous-valued opinions, which they adjust when they interact with agents whose opinions are sufficiently close to theirs. Our content-spreading model, which one can also interpret as an independent-cascade model, introduces a twist into BCMs by using bounded confidence for the content spread itself. We define an analog of the basic reproduction number from disease dynamics that we call an opinion reproduction number. A critical value of the opinion reproduction number indicates whether or not there is an “infodemic” (i.e., a large content-spreading cascade) of content that reflects a particular opinion. By determining this critical value, one can determine whether or not an opinion dies off or propagates widely as a cascade in a population of agents. Using configuration-model networks, we quantify the size and shape of content dissemination by calculating a variety of summary statistics, and we illustrate how network structure and spreading-model parameters affect these statistics. We find that content spreads most widely when agents have a large expected mean degree or a large receptiveness to content. When the spreading process slightly exceeds the infodemic threshold, there can be longer dissemination trees than for larger expected mean degrees or receptiveness (which both promote content sharing and hence help push content spread past the infodemic threshold), even though the total number of content shares is smaller.

Ichiro Suzuki, CC Sabathia, and Billy Wagner Elected to the Hall of Fame

Ichiro Suzuki, CC Sabathia, and Billy Wagner have been elected to Major League Baseball's Hall of Fame. They join Dick Allen and Dave Parker, who were elected to the Hall by one of the era committees in December.

As one can see in the voting results, Suzuki was named on every ballot except for one. (Therefore, Mariano Rivera remains the only player who has ever been elected to the Hall unanimously by the baseball writers.) Suzuki and Sabathia are both in their first year of eligibility, and Billy Wagner is in his 10th and final year of eligibility. I initially thought that Sabathia would get about 50% of the vote in his first year, but I saw quickly from the vote tracker (which I follow religiously every year) that he was going to make it this year. For Suzuki, the only question is whether or not he'd be elected unanimously. Wagner missed election last year by a measly 5 votes, so it was clear that he'd make it this year.

The strong election of Sabathia, the stronger-than-I-expected debut of Féliz Hernández (who got 20.6% of the vote), and the big gains of Andy Pettite (who roughly doubled his vote percentage from last year to 27.9% after making essentially no progress for several years) illustrate that the writers are looking much more intelligently than they used to at what constitutes a Hall-of-Fame starting pitcher.

Carlos Beltrán made a lot of progress to reach 70.3% of the vote. The newcomers on the 2026 ballot constitute a weak field, so Beltrán will surely be elected in 2026 and the other holdovers should make strong progress. Andruw Jones improved a little bit to 66.2%, and he may well be elected next year. I think it's about 50/50 that Jones gets elected in 2026 — a selection of ESPN baseball writers are much more optimistic than I am — but I am confident that he'll make it in 2027 (his 10th and final year of eligibility) if he does not make it in 2026. Jones barely survived the 5% cut on the ballot in his first couple of years, so he's made a ton of progress since then. Chase Utley also made a lot of progress this year, going from 28.8% of the vote to 39.8% of it. I expect that he will surpass 50% next year, but I think that he's likely still a few years from election.

Update: Here is Jay Jaffe's post to summarize the voting results and his thoughts on them. The navigation bar at the top of that website gives hyperlinks to his other articles for the 2025 Hall of Fame voting cycle.

Update (1/23/25): Here is Jay Jaffe's extended rundown of the election results.

Update (1/27/25): Here is Jay Jaffe's 5-year forecast of upcoming Hall of Fame elections.

What Happens in Athens (Georgia) Stays in Athens (Georgia)

I am heading off to Athens for my niece's bat mitzvah. Maybe I will see some homage to the Athens music scene at some point?

RIP Bob Uecker (1934–2025)

Former player, Brewer broadcaster, and legendary baseball personality Bob Uecker has died.

One of the great things when Baseball started broadcasting games over the internet many years ago is that I got a chance to hear Uecker broadcast a bunch of games. He was damn funny, an amazing broadcaster and storyteller, and a lifetime .200 hitter (as he sometimes pointed out with his wonderful self-deprecating humor).

You can read more about Uecker at his Wikipedia page.

What Happens in San Juan Capistrano Stays in San Juan Capistrano (Wildfire Edition)

UCLA is officially still online on Monday, so I am heading over to visit friends in San Juan Capistrano for an unplanned visit. If we are teaching in person on Wednesday, I will return on Tuesday. Otherwise, I will return at some later time.

Additionally, as in games like Pandemic, the regions of 'evacuation warning' (in this case) are also getting closer to my home region, so it's good to get out of town when it's prudent.

Update (maybe 20 minutes after I wrote the text above, with a scheduled posting for tomorrow afternoon): Then again, it looks like the Pacific Palisades wildfire has taken a hard east (though somewhat north of me) with some regions going from nothing to warning to GTFO very quickly. My region doesn't yet have even a warning, but the prudect act is to GTFO tonight and go to my friends already.

What Happens in Denver Stays in Denver (2025 Edition)

I am flying to Denver for the US Dynamics Days 2025 conference. I really love this conference series! This year, the conference hotel is actually about half a mile from the 2025 Snowbird-conference hotel.

I am really looking forward to this year's Dynamics Daze conference!