Being nerd-sniped by the h-index - by DavidXYu - XY-Wise
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Being nerd-sniped by the h-index<br>Graph Theory and Knowing Something
DavidXYu<br>Jul 20, 2026
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A year ago, a friend asked the question “how many countries can you name, for which you can name the same number of cities in those countries?”<br>For example, 3 countries, with 3 cities:<br>USA - New York, LA, Chicago<br>Japan - Tokyo, Osaka, Kyoto<br>Russia - Moscow, St Petersburg, Vladivostok<br>It is weirdly, weirdly sticky. Even a year later, I still find myself looking at maps and going “better commit a few cities to memory for this game”. One of the few things of this type that successfully worms itself into my brain.<br>It’s a questionable way to spend my time, but I spent a whole day working on it and resulted in an 8x8, which I’m pretty proud of.<br>A couple months after being introduced to the game, I introduced it to some friends, and they also got nerd-sniped on it. As people came around and asked what was going on, one friend explained that it was “the h-index for countries and cities”.<br>Ohh this is a thing!1<br>Where h-index is for academia, indicating the number of papers published that also has the number of citations, is a nifty metric for intuiting a researcher’s productivity and proliferate-ness.<br>Generalized, however, the idea becomes a useful metric to many things and I subsequently got nerd-sniped by this instead. The concept, while a bit unwieldy in everyday speech, becomes really useful for exploring and evaluating many things that I previously had trouble with.<br>It, for instance, somewhat resolves a conundrum I’ve long had on the question of “How many languages do you know?”<br>Every so often, this subject comes up, and my way of explaining has weird, awkward caveats:<br>“Uh, depending on how you count it. 3.5 or 4, I suppose, but half fluent on 2 of the 4, maybe? Depending on your definition of fluency.”<br>It feels like such an unsatisfying representation of fluency. What does it mean to know a language? It’s like asking: “Do you Know math?” What does that even mean?! So much needs to be assumed, while so little can be assumed. n I’m obviously being a bit stubborn on precision here. The standard response for both questions is really just “I know 3 or 4 languages and no, I’m not very good at math.”<br>There can be a lot more objective pinning-down of how many languages we know here by using the h-index. As in, we qualify and agree on the constraint of what parts of the total graph (all languages we know any amount of) counts for the purpose of this question.<br>For example, how many languages, n, you know for which you also know n words in that language? Which, for me, might be around 9. n Sometimes, writing a post is about flexing random knowledge you have.<br>Alternatively, a more telling one for the purpose of “knowing a language”: how many languages, n, you know for which you can also have 10*n minutes of conversations with a native speaker of that language?<br>For this version, I can then, satisfyingly, say 4. I feel like I finally can answer a question that properly satisfy me in conveying how many languages I know without over or under-selling what I know. Sweet, sweet precision!<br>Each variation also then gives different usefulness and insights. For example, while the latter is satisfying for how I want to address the question of how many languages I know, the former of knowing n words in n languages is a rough measure of how many other other cultures a person is likely minimally familiar with.<br>This is so neat!!<br>“Answers” are always constrained by the “Question”. Gaining new forms of asking questions allow us to touch answers that are invisibly constrained by the past ways of asking questions.
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Here is now a random assortment of ideas that I thought are neat and would find interesting asking others:<br>First, in the “how much math do you know” question, perhaps something like how many concepts in math, n, can you talk to a random audience for n hours on. This really helpfully pins down someone’s relationship to it, especially if/when the other person is likely to wriggle out of answering questions like this out of a weird kind of humility. Think the math genius at school that says they did poorly on a test and get a 96 or the former math phd who almost-confidently say they are not good at math.
How many concepts in any subject, n, for which you can talk for n hours about. This generalizes the above point for many, but not all, subjects.
How many countries, n, have you visited for which you have also visited n cities in those countries? None of that “Uh, I’ve been to the airport, does that count?” 😤
how many locations where you have significant lived-in memory: You’ve lived in N buildings. Rate each on a 1-N meaningfulness scale. What is the largest k such that at least k buildings are rated ≥ k? Sorry, convoluted, but helps represent something meaningful for me as someone who’s moved around a lot.
Simpler, how many cities, n,...