I had twice an opportunity to talk about responsibility and thigs related to it, and probably I should sum up not only my but also others’ thoughts on the topic.

The first, and foremost, requirement for responsibility is the possibility to consciously decide on an action. Not deciding is also a decision, but being unable to decide has nothing to do with responsibility. Hence, learning responsible beahvior cannot be done by passively observing other people, the actions of other people, or the results of actions of other people. This does not mean that you don’t have to observe; this means that you cannot be called a responsible person kust because you have visited a (generalized) museum, read some books, and know some more or less relevant facts.

It’s a little like math:  Responsibility is an ability. You are not a math graduate just because you can cite the Banach-Tarski result on cocktail parties. Instead, you are a math graduate because you know how to apply your knowledge to new problems. Applying the same reasoning to responsible behavior, we get that being responsible means having an idea what the results of your actions will be, making a choice that will benefit te people you care about, and not denying accountability.

One can see that in this reasoning, the group of beneficiaries is not clearly defined. Moral or economic imperatives may alter the definition of benefit. The core, however, stays the same: You have several options, you choose the Right Thing™, you accept the outcome.

To sum up, “let’s look at others’ experiences to learn responsible behavior” misses the point completely.

Philosophy ahead, brace yourself!

At some point in the past, I have discovered a wonderful, fully general argument against (some kinds of) biological research. The argument goes like this: “People should not be allowed to play God”. This sounds great, looks great and gives you an awesome +10 bonus to wisdom. But what does that mean?

This sentence implies that there are matters puny humans are not allowed to investigate, because meddling with them means a lot of responsibility nobody can be trusted with and is beyond the boundary of the socially acceptable. But that sounds patronizing and cold, right? And it opens the road to uneasy questions like “Where is the line?” that disrupt the generality of your shiny argument; note that in the “playing God” wording the decision is (implied to be) deferred to God. This sentence carries all the premises from Christianity: that the world has been purposefully created by a deity, that humans are no deities, and that humans are (unlike deities) not responsible.

I shall not discuss whether deities exist; in this context, this is mostly moot. The real problem here is that constructive arguments (like the lack of responsibility/control and what one can do about it) are replaced by irrational, faith-like constructs. Which is not okay since the discussion is about mundane, scientific things and has to be conducted via rational arguments and not via media campaigning and fast-food philosophy.

Optimization Heuristics, part III: The bitter pill

I have previously told you that the ways in which Nature works lead to surprising and wonderful results: Evolution produces human biochemistry, thermodynamics produces beautiful crystals etc.

I did not, however, tell you that it happens fast. Because it does not.

Homo sapiens took several million years to evolve. The thermodynamic processes are overly complex and happen on a vastly stretched time scale. And even then, the results are far from the optimum. Because, seriously, four blood types? The whole mammalian biochemistry? The blind spot? It is impossible to engineer that.

The main problem in the heuristics business is that even the most sophisticated nature-inspired process is just another clever strategy to randomly poke around in the search space. Because the problems (especially the complicated, we-have-no-idea-how-to-solve-it ones) have that rather bad habit of behaving not the way you want them to behave (because, otherwise, you’d just solve them in a traditional fashion). There is a famous result, called the No Free Lunch Theorem, which states that on average, all algorithms on all problems are equally bad. Bad means here exponentially bad, the kind of bad you do not want to mess with. One may argue that this result is a bit overrated, because we do not want to consider all problems; but even in the case when we restrict ourselves to “sane” problems with exactly one local maximum, it can still be shown that bad performance may occur, which makes “hard” guarantees on optimization time rather complicated. There are promising results for fluffy toy problems where the probabilistic machinery is not too awful. Still, for any real problem (like optimizing antenna designs) there are no theoretic bounds; but then again, any solution strategy that works for this kind of problems where there is little knowledge about the problem structure is better than none.

Optimization Heuristics, part II: Learning from Nature

Last time I have been talking about what happens when we have no idea how to solve a particular problem and I concluded that in that case, it might be useful to turn our attention to the nature’s way of solving problems. Today, I want to talk about the ideas we can extract from nature.

So, what does nature offer us? The most striking example is, of course, evolution. So it may seem like a good idea to simulate evolution. That usually means that you have a population of objects in your search space and impose some kind of selection pressure on those objects, making it hard for bad solutions to procreate. It is also usual to add some kind of mutation, since without mutation, you are not getting anywhere.

This sounds simple enough. But there is a catch: you might have noticed that, for current biological landscape to evolve, evolution was not particularly acting in hurry. The point of evolution is that it works at all, not that it is efficient. But nevertheless, evolutionary algorithms have been around for forty years and they do work really well in practice. There is also a notorious example of nozzle shape optimization, which is one of the main selling points for artificial evolution: no sane engineer could imagine such nozzle shapes, but search heuristics have no idea of “sane”, “intuitive” or similar, which makes them exploit all aspects of the problem, which is both good and bad: good since they can go ways no one would go and bad since they will explore a lot of places in the search space that are not necessarily interesting. Think about the configuration of the mammalian eye and especially the blind spot: No mutation can undo this now, the future humans (if they will not turn into cyborgs) are stuck with it, since the mutation distance between the current eye design and something more optimal is too huge.

Another great hit is simulated annealing which is not in the hot trends anymore, but the idea is still cool: The search process is modeled after thermodynamic processes in the lattice structure of cooling metals: with sinking temperature, the probability of changing the solution is sinking and the solution stabilizes like a metal slab is getting solid and reaches some thermodynamically optimal point in the process of cooling. This approach has been thoroughly analyzed and has several cool properties: for some rather hard problems, it is expected to deliver optimal solutions. The key word is “expected”: since the process is stochastic, no guarantees can be made. Actually, the property is rather weak. But it is nevertheless cool.

A lot of other heuristics have been developed: DNA computing, particle swarm optimization, ant colony optimization, and a whole lot of other techniques that borrow ideas from processes occurring in nature. But they all come with a price, because all of them have an ugly side about which I will talk in the next post.

PSA, For Science! (Optimization Heuristics, part one)

One of my next assignments is to write a (rather short, by my standards) essay on artificial immune systems. In the meanwhile, I will probably dump some of the background information (in a readable fashion) on you, my dear reader. Mostly for Science, but otherwise just to give my explanation skills a try. As I am not allowed to disclose my essay before the deadline, I will write something not quite about the topic, but about some interesting things from the general context.

Optimization Heuristics, part one, or How to stop worrying and start relying on Nature

What do I mean by “optimization heuristics”? Or, better, what do I mean when I talk about “optimization”? Optimization is a problem from the vast domain of mathematics, where it is often needed to find some value x which causes a function f achieve its maximal value. This boring stuff suddenly becomes very exciting when f is your income. Or the efficiency of your car’s engine. Or something else, completely unrelated.

As you might still remember from school, optimization was this task of finding the extrema of some awfully boring function. And you had to derive once, twice, thrice to be able to talk about the behavior or the function in question. So, what is the point of researching things about optimization, if any schoolchild with some knowledge about calculus can do it? Surely it cannot be so easy.

The sad part is, not only it is not easy, it is also very, very, very complicated. Your income does not behave like a nice polynomial function (or otherwise you’d figure out how to optimize it into the skies) and neither do flow properties of the air in turbines. In some cases, we cannot even write down the function in question in a fashion such that we can analyze it on paper.

This leaves us with a heap of unresolved questions. Surely, we know that there is some function which dictates the behavior of, say, a turbine. We can simulate the turbine. We can try various configurations and compare them. And that is it. The general kind of problems is called black-box optimization, for the details of the function to optimize are unknown to us, f is said to be a black box.

What we can do now is to try different strategies for searching the optimal input for f. The most trivial is to randomly poke into the set of allowed input values (called search space for intuitive reasons) and compare the results. This works with humans, why should it not work with machines? The main problem: this kind of search strategy can lead to long waiting times for optimization. Imagine yourself searching for a book in your friend’s bookshelf. You can jump randomly around, sure, but there almost surely is some system in which the books are arranged, right? Why not just search from the beginning? Well, this might work, but the bookshelf is large, and you’ll expect to go through the half of it before you find the right book.

We have to keep in mind that we just faced an inherent problem: Any of search strategies in a black-box scenario might lead to long optimization times, because what we are doing here is basically just poking into the search space with some more or less smart strategy. But this is the problem of the scenario and there is nothing you can do about it once you confine yourself to no knowledge about the behavior of f whatsoever.

So, what can we do, if we face a difficult problem? We might try to seek for already existing and working solutions. One of the first things that comes to mind is that somewhere, somehow, something similar happened in nature. The main problem with it is that nature has no optimizing goals. But some natural processes behave like optimization goals. So we could try to copy strategies from nature just because they seem to work and hope that it will work for our problems, too.

(To be continued)

Say NO to drugs and bad IDEs!

I guess I would be more productive if I spent the time writing this post actually coding for any of the two projects I have going on, but I have to vent or I’ll just go on swearing in real life.

So, one project involves writing generic neural network code and training it on robots. The first part is actually fun (if you can wait long enough and accept that your toy functions need a lot of time to get optimized). The second part is turning into a small nightmare. Why?

  • First, the idea is that the robots are tested in a virtual environment which is run by proprietary (and the bad kind of proprietary: the one developed by small companies with strict licensing policies) software that need to be connected to the license server all the time for no reason other than authenticating your license.
  • Second, the software provides a development environment. Which sounds better than it actually is—it is just an editor with code highlighting and keyword completion. Think Kate or Notepad++. While I have been coding somewhat non-trivial database applications in PHP, like, six years ago with nothing more than an advanced editor with code highlighting, I then was not bound by any kind of deadline or any other obligation—it was a “just for fun” project—and I moved later on to better-suited tools.
  • Third, the lack of any publicly available documentation makes me code by example, which is somewhat acceptable in a small context (as I will just need to plug in the sensors into the ANN and the ANN outputs into the robot driving system), but, generally, it is just impossible, since all the cool libraries (like Qt) are not available and I am left alone with STL and Boost.
  • Fourth, and the most important part: The run/test cycles are completely inadequate for a three-week project. Training an ANN for a robot means running the simulation in real-time and praying that the ANN topology is just right and the stars stand in the positions suited for such shamanic work.

This left me with one exit: I had to code and debug the ANN code separately. Which has its own fun parts since if you have no idea what to expect from a dynamic system, you cannot tell for sure if its behavior is the intended one. But the run/test cycles are here at least less than one minute.

(The current music running in my earphones—Kill Dash Nine by Monzy—reflects my feelings towards the Webots software package as whole and the buddies that come up with such problems)

Some words on software design

This post is rather technical, so skip it, if “overloading” primarily means severe working conditions and/or electrical circuit malfunction to you.

Two cool ideas that come from functional programming are

  • compile-time type safety
  • generic interfaces

They are very important when you try to design a library since you very often do not want incorrectly typed code to compile, which is somewhat hard to achieve since the OO world likes runtime dispatching, which may force you to impose too weak constraints on the types. Let me give an example of what I am talking about:

So what if we want to have a specialized Processor for some specialized Things? We probably will have to resort to runtime checks (in C++, you would use dynamic_cast, in Java, it would be instanceof) and throw an exception. Which is theoretically okay, but not really needed. The problem is that we mostly create the Dispatch class instance in compile-time and could control type safety without resorting to exceptions.

My idea was to replace the whole AbstractFactoryOfThings stuff with simpler specifications, like template-parameterized function objects that create Things because they are a subclass of some Factory. This way, the Dispatch class becomes Dispatch and we can safely mix and match the factory and the processor function objects without being endangered by runtime exceptions.

The whole thing comes with a price: You cannot mix the factory and the processor as a function of user input (theoretically, you can, but you have to construct all valid combinations first) anymore. Which can be annoying, but, if you design a library where Thing is something that should never be altered at runtime (like a fixed presentation), the described approach is perfectly sensible. Moreover, it generates less boilerplate code, since you do not have to come up with specific interfaces for Factory and Processor. They can be some sort of pre-defined Function<In, Out> classes.

So today I had my first lecture in Trondheim. It felt pretty much embarrassing as it turned out that the lecture language was Norwegian and my Norwegian skills were somewhat insufficient for attending a lecture (it got better during the 90 minutes, but not that much). Well, the lecture was not of my primary interest anyway. (That is the undisputed pro of universities in English-speaking countries) But then, I managed to get a Norwegian mobile number, so the day was not entirely unproductive.

Between lectures, I was reading more stuff from Less Wrong (yeah, I am advertising a bit 😉 ); mostly, the ideas depicted there are pretty much sensible and one of the most important ones can be compressed as follows: Any worthy (scientific) idea has to decrease entropy and narrows down explanations. Example: Saying “The system shows emergent behavior because of its great complexity” is not an explanation since it uses buzzwords without revealing any details. Another things that are worth reading are the articles on cognitive biases. They make me want to replace my rusty old brain with an inference engine (if possible, clocked at the same speed, thank you). And, if you want the same stuff, but wrapped into a story, just follow the link. You have been warned.

Oh, and pictures for attention attraction:

(This one is brought to you by my tripod)

And this is a nice view of the city center (yes, it is not that big) with the Nidaros cathedral on the right and the fjord in the background.

A few words on Science

As a (somewhat) frequent reader of the Sequences on, I was always wondering about the seemingly-abusive usage of the word “Bayesian”. Being curious as a proper wannabe-scientist has to be, I tried to investigate the issue. And oh dear, why did I even do this.

After half an hour worth of research, I have found out that there are two competing views in scientific methodology that can be traced back to two different views on inference models. Long story short, if you compute P( Data | Model ), you are a frequentist. If you compute P( Model | Data ), you may proudly label yourself as a Bayesian.

Okay, but seriously, can it be a serious scientific issue? Apparently, yes. (Google: 265K hits on “frequentist versus bayesian”) Most Google links lead to blog posts in which authors argue for their favorite toy model by giving examples in different kinds of weirdness. Frequentists give obvious toy examples, Bayesians reply with taking the examples and showing that with advanced probability-fu, one can get better results (if the example behaves well), then a debate on the philosophical implications of iteratees inference begins…

Don’t get me wrong: I somewhat like the Bayesian point of view, since computing the probability/likelihood of the model seems to be more straightforward in terms of scientific reasoning, which is about testing models, not data. But in the end, you still have to justify your statistical model used in inference (contrary to: “yo dawg, I heard you like probability distributions, so I took the Beta distribution: and put it into your model so you can compute more funny numbers!”). This is especially relevant since there are MANY inference models around (all of which are pretty much awful in terms of computational tractability, but that’s a different issue).