Thursday, February 26, 2009

Homework and Search Engines

It's safe to say that search engines have made the lives of most teachers and professors significantly harder. When I was in middle school, half of my homework consisted of answering dumb questions like "when was Isaac Newton born?" just to test whether we had done the reading. Granted, it was possible to scan the document without actually doing the reading but usually there were enough questions that it was easier to just read the thing.

On the positive side, I think such questions were a big waste of our time so the existence of search engines is (hopefully) making middle school teachers ask questions that require a little more thought.

On the negative side, search engines are adding more work to me! When I teach 15-251 (CMU's version of discrete math for computer science), most of the classic problems (and their solutions!) can be easily found on the Web. I'm always torn as to what strategy to follow to deal with this issue:

  • Ignore The Whole Thing and Do Nothing. Pros: It's easy. Cons: Kids don't learn how to actually solve the problems if they just Google for the answers.

  • Police State (my current approach). Make searching for answers on the Web be considered cheating in the class and punish them harshly if they cheat. Every year, we set up "Google Traps," in which we assign a problem with a unique name like "Giramacristo's Puzzle." We then publish a Web site that has a solution to "Giramacristo's Puzzle" and make sure it's the first result in Google for that query. Since we control the Web site, we can record all IP addresses that visit it and later correlate them with students in the class. We catch approximately 10% of the students in the class cheating. Pros: It's fun! (for me), and if you do it early in the semester they learn never to search for answers again. Cons: It requires effort. In addition, it's not clear that disallowing search engines is good preparation for life -- after all, they'll be able to use the Web when they're out of school.

  • Allow Searching on the Web but Change the Problems. Pros: In real life they will be able to use Google. Cons: It's hard to come up with good ways to change the problems, and inventing brand new problems every year is even harder, especially if you want them to be as good as the classics. My advisor Manuel Blum has recently been thinking deeply about this and he told me a good strategy: for most problems (at least in theoretical CS), you can change them significantly by thinking "how can I make this problem be closer to reality?"

Sunday, February 22, 2009

Bad Research Talks

I'll admit that I'm particularly bad at understanding presentations because I have no patience -- "This is boOOooring. Hmmm, what am I having for dinner tonight? Oh crap, what did they just say?" ... and then I'm lost for the rest of the talk. But people, please, at least try to make your talks accessible. Many conferences now have "best paper" awards; I think they should also have "best talk" awards so that everybody tries harder. Related to that: WHATEVER YOU DO, UNDER ANY CIRCUMSTANCES, DO NOT USE BULLETS IN POWERPOINT. ALSO, ALWAYS TURN OFF AUTO-RESIZING OF FONTS. Your fonts should be 28pts or higher, and the size should be uniform throughout the presentation.

If more than 75% of the audience thinks a talk really sucks, we should ban the speaker from that conference for the next three years. After three such infractions, the speaker should be voted off the research island.

Thursday, February 19, 2009

Crackpot Idea #237

MBA programs should charge a percentage of your future earnings instead of tuition.

Granted, there would have to be a "Dean of Collections" with a team of thugs in case you don't pay -- "This one's from CMU <wham!>" But look at it this way: (1) universities would then have a major incentive to make you rich, and (2) anybody could afford to get an MBA.

Monday, February 16, 2009

I'll Wear Your Clothes for Money

Times are tough for universities everywhere. Shrinking endowments have forced some schools to close departments, some to double tuition, and many others to freeze salaries and hiring. While the administration claims that CMU is doing better than its competition, I can't help but thinking of steps to guarantee that we can make ends meet.

I therefore have decided to start a limited-time offer: I'll wear clothes with your logo for money. Think about it, big software companies, what better way to recruit the top students than having their professor directly advertise to them? You'll see the results faster than you can say "Targeted Advertisement!"

I will wear your paraphernalia during every lecture. The prices quoted here are per semester.

Saturday, February 14, 2009

Valentine's Day

Instead of spending time with my lovely fiancee, I've been thinking about dating sites. Before you romantics start yelling at me, (A) I'm cooking for her soon, and (B) this is strictly for work purposes: I'm trying to figure out if we can get people to do useful work while they flirt online (ideas about this are welcome). Just imagine: below the picture of a hot girl the site could say "This person is looking for somebody who can speak both French and English. You must translate this Wikipedia article to French before you can go on a date with them."

Anyhoo, related to dating sites:

  • One thing I'm wondering is how the very first person signs up to a new dating site. If the site is completely empty, it makes little sense to spend time filling out a profile. I guess the same happens with new social networking sites, but the problem is more pronounced with dating sites, since there is (still) some stigma in writing a profile, and since you get no benefit out of a dating site unless it has people who are not your friends. My guess: new dating sites put fake profiles to seem more popular.

  • Has anybody done a good study comparing online versus real world dating? I've seen a few, but they are all pretty much bunk: either they have ~5 subjects (note to the HCI community: let's please stop writing papers with only 5 subjects), or they are done by the dating sites themselves (sorry, eHarmony, I just can't believe your propaganda). The study I'd like is a long term one: if you meet online versus in the real world, what is the probability that you are still happily together 10 years later? My personal guess is that unless the study is done carefully, online dating would win big because of a sample bias.

I don't think my fiancee reads my blog, so let's not tell her what I've been doing all day.

Thursday, February 12, 2009

You Can't Join My SECRET Site

"Refer a friend" button: okay. Bigger "refer a friend" button: I can take it. Forcing me to give my gmail password so that you can invite everybody I've ever emailed: NOT cool.

Over the last couple of years I've seen many sites use increasingly more aggressive tactics to get you to invite your friends to join the site. My favorite are the ones that innocently ask you for your gmail password (to save you time, of course), and don't quite tell you they're gonna email EVERYBODY you know saying "Luis is PERSONALLY inviting YOU to join!" I understand the desire to become viral, but at some point you have to wonder whether this actually works. From a psychological standpoint, I would assume it's not great to seem so...desperate?

So I'd like to try an experiment using the opposite tactic: making everybody want to join my highly exclusive, SECRET, site. If you join the site, the first rule is that you cannot tell ANYBODY about this site (like Fight Club). The only way to join is if somebody who is a member tells you the secret AND if all the current members vote you in once you know the secret. But that's the kicker: it's against the site rules for a member to tell anybody the secret, and if we find that a member told somebody the secret, we throw them out. So the only way for the site to grow is if the members secretively tell the secret and then lie about it. Let's see if we can make this grow faster than

Tuesday, February 10, 2009

Real Men of Genius: Mr. Domain Name Hoarder

Today I salute you, Mr. Cybersquatter. When nobody thought of buying or, you saw a business opportunity. I salute you for stifling my productivity and the progress of humankind by owning every name that could be interesting on the Web. For making me waste my time and money when I don't want to settle for a .biz domain. For crawling the Web to find strings that are mentioned often and buying the associated domain names. Thank you.

[Editor's Note: After spending hours yelling at his computer, Professor von Ahn would like to finally strike back against squatters by somehow making them think uninteresting strings are actually valuable names so that they buy them and lose money.]

Sunday, February 8, 2009

Some Tough Questions

  • Reporter: What's your ultimate goal? Luis: I'm trying to get computers to do everything humans can. (More honest answer that I didn't use: I want to watch more TV.)

  • Reporter: But, what will *we* do once computers can do everything humans can? Luis: Computers will be our slaves and we'll dedicate our lives to watching TV, playing sports, and philosophizing. Personally, I'll watch more TV.

  • Reporter: Aren't you scared that computers will take over the world when they become smarter than us? Luis: I'll tell you a great quote from Pedro Domingos: People fear computers becoming smarter and taking over the world, but currently computers are not very smart and they already have taken over the world!
  • Thursday, February 5, 2009

    Academic Publications 2.0

    Maybe I'm in the wrong line of work, but I hate writing academic papers.

    • Current conventions in computer science mandate that each time I write a paper, I should state my result four times: once in the abstract, once in the introduction, once in the body, and once in the conclusion.

    • The introduction section is, to a large extent, a waste of everybody's time. Nearly every paper about a given topic has the same introduction: "Topic X is important because A, B, C."

    • Here's a simple formula that seems to work for (and is overwhelmingly used in) computer science papers:

      Abstract: We solve problem Y.
      Introduction: Problem X is so important, that if we solve it, the world will be a much better place. Y is an approximation (or subproblem) to problem X. We solve Y.
      Body: Here's a convoluted explanation of how to solve Y.
      Conclusion: We did Y. Doing X would be awesome.

    • Once a paper is "published," it is set on stone and cannot really be changed, even if you find a much better way to convey the results or if you find that the data is better explained by a different hypothesis. The reason for this restriction is that, 30 years ago, papers were published using physical paper. Such a restriction makes no sense today.

    • As an academic community, it sometimes feels that the final goal of doing research is publishing papers. The goal of doing research should be, well, doing research. I understand that communicating the results of our work is important, but surely there is a better method than one that was invented before computers were around.

    • Given the number of people working in computer science and the fact that publishing papers is considered the goal of our work, there is an insane number of papers written every year, the vast majority of which contribute very little (or not at all) to our collective knowledge. This is basically spam. In fact, for many papers (including some of my own), the actual idea of the paper could be stated in one paragraph, but somehow people manage to write 10 pages of it.

    Can a combination of a wiki, karma, and a voting method like reddit or digg substitute the current system of academic publication?

    Tuesday, February 3, 2009

    Why Don't Students Tip Professors?

    I hate tipping. I do it, but (A) I usually don't carry cash on me (who does these days?), and (B) I don't understand the logic behind who should be tipped and who shouldn't. Why do we tip waiters but not flight attendants?

    But most importantly, why don't students tip professors? In this economic downturn, every cent matters. If we do an ok job, we should get 10% of the tuition for that lecture. For an excellent job, we should get 20%. Given that students pay ~$100/lecture, and that my class has 200 students, I'd be getting $2,000 every time I give a mediocre lecture and $4,000 every time I give a good one. This will surely increase the quality of education.

    Alternatively, I guess I could start singing about God and send the TAs with baskets around the class to collect money.