Path-Sensitive

It’s a sunny day in Santa Cruz, and Alice is showing Bob her new app:

Alice: This is Frosttly, my new on-demand delivery service for cupcakes. 

Bob: Cool! How does it work?

Alice: It’s based on the Uber and Google Maps APIs. Whenever, you press this button, it texts one of our Cupcake Delivery Specialists your current location and summons an Uber so they can bring you cupcakes. 

Bob: Wait; there’s got to be more to it than that. 

Alice: Naturally, this is just a prototype. The final version will integrate directly into the order system for a specialized cupcake kitchen, and will feature sophisticated order tracking and highly optimized routing of deliveries. It’s fully functioning though. Go ahead; try it. 

Bob presses the button, and hears Alice’s phone vibrate in the other room 

Bob: Wow, it works! I can’t wait to get my cupcakes.

If you’ve ever been to a hackathon, you might have seen plenty of conversations like this. Elsewhere, Billy is showing Alyssa his prototype of a new dessert: he poured confectioners sugar over an antique dinnerware set to create something light and fluffy with a rustic feel (the final version will also have chocolate and goji berries). Billy’s concoction is much closer to a final product than Alice’s cupcake service without cupcakes, and may have even taken more work than her handful of lines of code. Yet still I’d be surprised if I saw anyone calling a pile of sugar a prototype dessert. What makes one a prototype but not the other? The resolution is simple: there’s no such thing as a prototype app.

A few years ago, my working definition of a prototype was simple; you build enough of your plan to get a sense of what the final version looks like and show you could build the whole thing. The prototype of my app for playing arbitrary card games was a screen where you could drag-and-drop rectangles. The prototype of my game mod used hand-crafted assembly to make changes. This breaks down when you stop to think: what aspect exactly are you trying to figure out?

Some people walk into Jesse Schell’s Game Design class expecting an easy time, and are shocked to find themselves pulling multiple all-nighters for a class where getting a 100% on everything is only enough for a B. But those that persevere find themselves with new worldviews on everything from sleep to applied probability theory, and learn why there’s no such thing as a prototype app. As Schell states in his book “The Art of Game Design,” a prototype is defined not by the product it steps towards, but by the question it’s intended to answer. And depending on the question, the form of the prototype can be very surprising.

So, what’s a prototype for Tetris? You mean: something to figure out how the blocks mechanic works in practice? Get a friend to cut some shapes out of paper and start sliding them down a grid. It might not make for the best Tetris experience, but it takes about 15 minutes to get going, and it’s enough to start getting a feel for how the shapes work together.

The team for the game “Prince of Persia: Sands of Time” wanted to figure out how the acrobatics in the game would work. Their prototype was just a few animations of different moves, plus a bit of imagination.

Designing the gameplay for a new first-person shooter? Try flashlight tag. Designing the atmosphere? The prototype is also called “concept art.”

And for hardware? Nintendo showed us the difference between design and technological prototypes in 2005 when they unveiled the slick look of the Wii while having modified Gamecubes running behind their demo booths

It gets even more interesting once you leave the realm of games. Jeff Hawkins of Palm prototyped the user experience of the Palm Pilot by carrying around a block of wood in his shirt pocket. He would frequently take it out to “check his schedule” or “look up a contact.” Whenever someone suggested a new feature in a meeting, he would take it out and ask them where it would fit. Meanwhile, I told a friend at an assistive robotics startup, that, while their current project does serve the purpose of a technological prototype, he could build a prototype to test the value proposition much faster by simply going to his grandparents’ house and pretending to be a robot.

Prototypes and MVPs

Like everything else in Lean Startup, the idea of a “minimum viable product” has been passed around the Valley in a game of telephone until its meaning is perhaps less than that of the three words stuck together.

A minimum viable product is a very special kind of prototype, one that tests the two key factors behind a startup’s success, what Eric Ries calls the value hypothesis and the growth hypothesis. Typically, this constrains the MVP to more resemble the actual product, but not necessarily. In 2008, Dropbox hit a key milestone on the path to their MVP when they released a video demonstrating their product. Tens of thousands joined the waiting list. So actually, the minimum viable product was the video itself: they had already proven that lots of people (growth hypothesis) want what they’re building (value hypothesis).

Similarly, the MVP doesn’t need to work internally at all like the final product. Lean Startup contains a couple examples of this: the ingredient-delivery and meal-planning service “Food on the Table” started with the CEO making deliveries to one woman, and didn’t even try to add automation until forced to. Alice’s app may not be a technical prototype of anything other than the ability to send texts, but if she can do enough behind-the-curtain work to get real users and see how they respond, it’s enough for a perfectly fine MVP.

Unpacking the Confusion

Prototypes for design questions, engineering challenges, usability, market. Demos for users, investors, the press. Why do people seem to want to combine them all into one mythical “prototype?” To show they can build it? Surely they realize that, for a typical web app, the answer to “Can I make this?” is usually “Yes” if not “Yes, but why?” And why is it weird to prototype an RPG game’s combat system with pen and paper, when many of them are just digitized versions of physical predecessors?

I think it’s simply a case of a more general phenomenon. The best way to learn to play a song may first involve drills with nary a bar from the final piece. The charity that makes you feel great and does a lot of good may actually be two charities. When you learn to identify what things you want, it’s often best to get them separately. So let’s lay rest to the idea of a prototype app. Forget about about prototyping your product as a whole. Find the underlying questions, and answer them.

Thanks to Jonathan Paulson, Amy Quispe, Nancy Hua, Michael Poon, and Melody Guan for comments on earlier drafts of this post.

You’re in high school, trying to get into a good college. You know what you must do: do well in classes, score highly on the SAT, and be active in extracurriculars — and do it better than everyone else.

Actually, I have a different suggestion: train with a friend for the USA Biology Olympiad, score highly in the first two rounds of exams, and qualify for the national training camp and then the national team.

Only a handful of people can follow that strategy. But anyone who could play the standard high-school achievement game and have a good shot at getting into MIT or Stanford could instead play the Olympiad game and have a great one. The USABO is disproportionately high-utility compared to how competitive it is. It comes with a free trip to a national training camp where you receive intense training in biology and bond with a few dozen other top high-schoolers. There are vast swaths of America, including lots of high schoolers studying hard for the SAT, who have never heard of USABO. And yet there are communities where training for Olympiads is such a well-known option that it barely counts as a strategy.

My friend who did this and got into all her colleges didn’t do so by playing the standard high school game better than her competitors, but by stumbling into a different game entirely. In doing so, she could do things the others couldn’t. I think this a fairly common pattern: a lot of what’s involved in making it to the top of anything is not being better at things than other people, but outright being able to do things they can’t. In business, they call it a “competitive advantage.” Peter Thiel calls it a “secret”. For personal life, I like to call it a “source of power.”

The “other people can’t” is the big part. As a source of power percolates into society, it loses its power as an advantage, although whether you should stop doing it depends on whether its value is external or innate. As an example of the former, 200,000 people compete in the American math Olympiad qualifier rounds each year, so training for the math Olympiad is not such a good move for most people. It’s prestigious, but only in proportion to how competitive it is. In economic terms, the free lunch has been eaten. Meanwhile, when Benjamin Franklin was working in London, saving up to open his own print shop, he found it easier than most to be frugal due to his insight that strong beer does not grant physical strength. They nicknamed him the “water American.” Nowadays, his insight is common knowledge, but that doesn’t make it less effective. Instead, it becomes the new bar.

As a warning, I found when writing this that a lot of examples of sources of power I used or wanted to use would strike a lot of people as weird, but it would take a lot of space to justify them. This is inevitable in retrospect: if it’s considered normal, it’s no longer a source of power. I also noticed while writing this that a lot of my examples focus around high school or college. I think that’s largely because life tends to diverge afterwards, and the examples become much more niche.

Discovering Sources of Power

How can you learn about new opportunities before other people suck them dry? How can you find ways of being better before they become background knowledge? While CEOs often spend much of their time looking for a leg up on the competition, I think there’s enough sources of power and few enough people looking for them that simply trying is enough. In fact, sources of power are sufficiently exploitable that there are many algorithms for finding them with high success probability.

Often, they’re hidden in plain sight, waiting for anyone to read. For a basic example, right now a degree in computer science is a ticket to a decent life. Right now, the meta-skill of “study things that are valuable and will be in demand” is sufficiently uncommon that you can raise your expected earnings (or, dare I say, life outcome) significantly just by following it. Look at the distribution of college majors if you’re not sure. I think the same further applies to specializing in hot-but-difficult subfields like natural language processing or security. Right now, CMU’s Plaid Parliament of Pwning is winning tens of thousands of dollars from application security competitions every year, while only a handful of other American universities have a team at all. More broadly, this idea also applies to entering STEM in general.

This is basically staying ahead of the demand curve. When it comes to personal skills, demand is slow to propagate, and you can gain a lot simply by being faster. Since knowing that you can raise your earnings by becoming a programmer or moving to North Dakota doesn’t cause everyone to instantly become a programmer or move to North Dakota, it will remain exploitable for anyone who wants for quite some time.

It’s interesting to think about trying to be even more ahead of the demand curve by making a big bet and training in what will be hot. This involves predicting the future. But, in life as in stocks, the winner is often not someone who knows what will happen, but someone who figured out slightly more than everyone else. And, for predicting the future, not many are trying. Along these lines, I was surprised when I learned that several prominent companies in the mobile space — in particular AdMob, acquired by Google for $750 million, and Flurry, whose software runs in over 100,000 apps — were actually founded in 2005 or 2006, before the iPhone’s announcement ushered in the modern mobile era. I think a lot of people knew the mobile revolution was coming, although perhaps not that it would be so fast. The people bold enough to actually act on that prediction were in a very good spot when it happened. I’m hoping to do something similar for program analysis.

From Who You Know to What You Know

A lot of the above could perhaps be summarized to find ways to be effective. The interesting part is how people find sources of power. One way is to invent it yourself, whether by finding a loophole, noticing a trend, or doing science. While there are a few places where it’s clear that investigating it may result in disproportionately better capabilities, this can run out of steam pretty fast. It may be possible to gain vitality by eating better, but the reward curve of doing nutrition research probably more resembles climbing the corporate ladder. Most often, the way to find a source of power is to hear of it from other people.

I think it’s a pretty simple effect. People with similar interests like to cluster, but people who also really care about improving will cluster further. They might be able to invent one or two sources of power on their own, but then they share it with the people around them — who also have a secret or two. The effect compounds, with the benefits from sharing ideas dwarfing the loss of exclusivity. Just as IBM found their above-average testers becamedozens of times better when grouped together, what you get are communities that collectively have and share the best ways of doing things. So the way to get good at something is to simply find the right community and join it.

So, for example, you’ve probably heard weight-loss advice from everyone from talk show hosts to your neighbor. This suggests that you can do better by talking to bodybuilders, who can control exactly which day they’ll hit their goal.

But this strategy can be easier said than done. The problem is not the joining: these communities are rarely exclusionary. The problem is the finding: every community wants to seem like them. They get drowned out in the noise.

In 9th grade, I attended a local programming contest. I spent a morning running floppy disks to the judges, and left with a full belly and $500 — I had won by a sizable margin. I immediately went home and Googled for more high school programming contests. I found a pen-and-paper competition in which you answer multiple-choice questions about the BASIC programming language.

I often wonder how my life would have been different if I had instead discovered the USA Computing Olympiad.

For another example, it’s well-known that to get stronger you need to push your muscles to their limits — and specifically their strength limits, rather than their endurance limits. There are vast swaths of the Internet where everyone understands what implications this has for training, with plenty shouting it at the top of their lungs. But if you look around for advice on “how to get fit,” you’re perhaps more likely to find advice to do lots of crunches, or warnings that weights might make you look like a steroid junkie. One journalist described crossing this gap as “I somehow bumbled my way into a parallel universe of American fitness, one in which men know exactly how to get strong.”

Passing It On

As we’ve seen, while sources of power with intrinsic value may merely descend from insight to platitude over time, the externally-valued have a shelf life. Perhaps the big warning from this is for those wishing to help others be successful, especially parents. As Paul Graham wrote, parents are like generals always fighting the last war. I remember seeing a teenager on CollegeConfidential complaining that their parents wanted them to stay home all summer and study for the SAT. Perhaps that would be a rational choice in their home countries, where college admissions were and still are based on grueling exams. Yet here the most advanced standardized math test for college admissions is the Math SAT Subject Test, where it’s possible to miss 7/50 questions and still get a perfect score. Meanwhile, my own mother had occasional aspirations of being a “white tiger,” and would often cajole me during my hacking sessions to “stop playing Java” and go study for the SAT.

This realization — that all these secrets and sources of power I’ve spent so much effort finding might backfire when I try to pass them on — is what scares me. I imagine becoming a parent telling my children to train for Olympiads, not knowing that that’s become advice about as good as spending a summer studying for the SAT.

I think the defense is to recognize the phenomenon but go a meta-level up. Why are people at the top of one field often very good at another? Is it merely grit and intelligence? Just as there’s a meta-skill of finding sources of power, I think there’s a skill of finding and recognizing the people with the genuine secrets, versus the posers and people out to get your money. I believe there’s a way to recognize genuine competence that transcends fields (related concept). That’s a topic in and of its own.

So, find your sources of power, but pass on the meta-skill of finding them. To get your children into college, help them find the new secrets.

And, of course, that’s assuming college admissions are still worth obsessing over.

Thanks to Jonathan Paulson, Amy Quispe, Jessica Su, and Nancy Hua for comments on earlier drafts of this post.

I like doing things right.

When I wanted to make infographics for my paper, I spent hours picking out the best graphics program that I’d use for years to come (why waste time learning the wrong one?). When I was dieting, I didn’t want to buy new clothes until I hit my target weight. And so, when I decided to create a blog, I knew it would have to be the Best Blog. I would need to get a great design, put it on a great domain, and fill it with the sharpest posts consisting only of things I’ve thought about at least 3 years.

Oh and in case I started to get other ideas, my new blogging inspiration is Christopher Olah, who will often spend a month on a post complete with 3D animations of folding surfaces, and then get it on the front page of Hacker News.

In “The Lean Startup,” Eric Ries discusses the concepts of large-batch vs. small-batch thinking. A father and a daughter race trying to mail a hundred letters. The daughter, having recently learned about the assembly line in history class, first carefully first folds a hundred messages, then stuffs them in a hundred envelopes, and continues licking, stamping, and mailing each in batch. The father does everything one at a time: folding, stuffing, and sending each letter before beginning by next.

Who wins? The father, by the power of author fiat. But also by flexibility. No need to invest in table space. And what if the messages didn’t fit in the envelopes? The daughter would fold all 100 before finding out.

I admit it. I’m naturally a large-batch thinker. I live life as if every step I’m aiming myself like a rocket bound for Pluto. I study the long-term impact of software design decisions, decisions that, more often that most people realize, cannot be undone. And so it feels unnatural to remind myself that I can change my mind later.

Last year, I wrote an essay telling the story of my startup and my ensuing decision to go to grad school, and posted it privately on Facebook. People loved it. Friends I hadn’t spoken to in years E-mailed me to say how much it touched them.

It took two months to write, and was out of date by the time I finished.

I don’t want to go through life only saying things good enough to shout from the rooftops, or only doing things that I’d display on my resume. One of the most inspiring recent blog posts on research was written by Phillip Guo on an iPhone during a coffee break. That’s skill, and it didn’t come from spending two months on each post.

Words on the Internet may be written in ink, but that doesn’t mean that my persona is. I don’t need to pick the title I’ll be using for eternity. I don’t have to pick my life’s writing topics. I don’t need to pick the writing style I’ll forever be known for. I don’t even have to attach it to my domain name.

So, this is my first blog. It’s not the platonic blog, but it exists.