Phones have a bit fewer, but I think you'll find at least about 10.
A simple cheap SD memory card has an embedded core, usually ARM7TDMI. Even most lithium batteries have an integrated microcontroller.
I'm also a programmer, I do bare metal embedded, kernel drivers and such. I often don't have anyone else to ask from, except occasionally hardware guys. They're also often stumped.
So in a high profile case, like the Tesla Autopilot fatality, if the behavior was traced back to a specific micro-controller, it might be just as hard to determine why the system behaved as it did, as with a complex neural network? Even with a company's reputation at stake, it's not possible to hire a consultant with a deep understanding of obscure micro controllers?
I only deal with the source code level, don't really have experience digging into the hardware level.
http://www.edn.com/design/automotive/4423428/Toyota-s-killer...
Components have always a set of intended behavior and some, often unknown or poorly understood, set of unintended behavior.
It's very important to understand that abstractions mask both intended and unintended behavior.
You deal with unintended side the best you can, with sanity checks and so on. But some of it inevitably leaks through.
Those outcomes that result from multiple systems being individually in good state but collectively causing undesired behavior are often very tricky to understand. On the flip side, when you do understand them, you tend to gain new surprising insights into the whole system.
Also timing makes understanding hard. When it comes to a complex network of systems, it's hard to concurrently reproduce the state where the effect occurs.
> So in a high profile case, like the Tesla Autopilot fatality, if the behavior was traced back to a specific micro-controller, it might be just as hard to determine why the system behaved as it did, as with a complex neural network?
If Tesla has good, exhaustive, event logging facilities, a "black box", I guess they'll be able to figure out what happened by analyzing all of the available data with the systems knowledge they have.
Anyways, if it's not systematic, why should Tesla autopilot mistake be handled so differently from a human being making a mistake?
You can't analyze why a human being caused an accident either. The best you can usually do is to develop scenarios "theories" based on the available evidence, but that's it.
Way, way back, I had an 8 bit computer that I built myself from chips and solder. The "permanent" memory was 16kB; I knew most of that code pretty well. Even then the CPU itself required quite a bit of study to comprehend.
There are pretty significant limits to our conscious, logical understanding of the world.
In both cases we can only fix a particular instance of an error and effectively have no way to show that similar errors don't exist, or even that we didn't introduce new bugs with the fix.
My point was not something about manipulating weights directly vs. augmenting the training set. The analogy is roughly, find a misclassification : add particular input to training set :: find a bug : add a patch/test case. I'm playing devil's advocate, of course, and there are obvious, important differences.
> The difference is that all human written systems was once understood by a human
But that's not one of them! In practice, we create software systems by getting some rough intuition about an interface, wiring together some components, then checking the results empirically. Basic components that everything else is built on, C compilers for instance, are based on ambiguous, even contradictory specifications.
Unfortunately, adding that particular input to the training set may mess up the ANN when given a different input (i.e. you fix one bug but create one or more new bugs, like a game of whackamole but where people die)
Can we actually do this, for complex ANNs?
Additionally, the weights are constant in production, which makes analyzing production issues just a matter of logging the inputs and the outputs. Of course, for most convolutional nets, the inputs can get quite large (for example, a camera feed).
I think the key problem right now is that there are not too many models for which tracing the execution lets us know much about what's happening. A single decision tree. A linear model. But add ensembles to trees or layers to linear models and the ability to understand what's happening through logging disappears.
In this sense I think we're essentially in the pre-assembly language state of machine learning. For most programming languages, we assume correctness as a given. If it produces the wrong result on correct inputs, that's really bad.
With machine learning, we don't have perfect correctness. Aka accuracy. We focus so much on improving accuracy that we rarely consider the trade-off in debuggability or interpretability.
I think this will have to change. Advances in NLP and image stuff from deep learning are very exciting. Ignoring the evil AI concerns, I think the best step will be trying to understand better why the models did what they did. I think it will be a while before we can just ask the model and get a reliable answer. In the meantime, I think we'll work on a kind of meta programming where we integrate models better with their broader context. An example might be sequence to sequence models that have a way to expose sentence fragments and documents in the training set that influenced a word choice. Or automatic labeling of clusters in image representation layers that have semantic meaning to a human. There's some interesting work already on debugging tools for image classification that I really liked. On the phone so I'll try to provide the link later.
The trouble is it all seems very domain specific. Figuring out how do it in a way that's not so domain specific is i think a very interesting thing to work on.
Obviously no one has a full mental model in their head of everything going on in their phone (for example) at a given moment in time. But when it really matters, and there is a specific question to answer, and a programmer with experience writing the kind of software in question has full access to all of the source code, its possible to get an answer to why a program behaved in a particular way.
I'm a programmer, and this is what I do every day.
And in those rare cases where knowledge of the specific hardware is required, there are experts who understand the hardware and can answer the relevant questions.
So for machine learning approaches, what is the equivalent of the "source code"? What resource is there to examine to determine how the system will respond to a given set of inputs, and why? Evidently, there are not clear answers, at least for some machine learning approaches.