Can someone here please explain whether the use of Mechanical Turk here is a cop-out from building a better computational model, or just an ordinary use of supervised learning in place of unsupervised?
The talk they gave, "Deep learning for NLP (without magic)" was pretty good: http://techtalks.tv/events/312/573/
- certain combinations of words within phrases score all over the place
- hand those to mechanical turk for human classification
- understand where the results differ from the model
- patch the model where necessary when it breaks down.
The example they gave with the "but..." at the apex of the sentence is difficult primarily because it's ambiguous to what proceeds it. It could be positive or could be negative, especially from a programmatic standpoint.
Really fascinating stuff. Can't wait to see the code.
If the model is telling us that it is uncertain about specific examples, and would like more information on examples like those, that's active learning.
That sounds different from what you describe in your post, depending on what you mean by 'sometimes the model is wrong, so we hand the data off to a human being'.
It depends on how we know the model is wrong.
If we know its wrong on a test datum, which is part of a big set of test data humans labelled without any input from the model, then its standard 'supervised learning'.
If, instead, the model is 'wrong' because it expresses uncertainty for particular test data, then, if we go and have a human classify that data it was uncertain about, and retrain the model, then we are probably doing Active Learning. In this case, the model/system is (at least partly) guiding the learning process.
Reinforcement learning is neither of these things exactly - it describes a more general framework, where the system is getting rewarded based on how well its performing.
Lets say you want to choose 1 of 5 labels for each datum. In supervised learning, the system gets given the right label for each training example. In a RL setup, it might be shown an example, have to guess a label, and maybe be told if it got the right guess, but if it guessed wrong, just told it was wrong - but not necessarily told what the right answer was.
There's a little fuzziness to how all these terms are used in practice.
[0] http://en.wikipedia.org/wiki/Active_learning_(machine_learni...
So far I think they're accurate. Homework 1's due in a few days, but the lowest 2 homeworks are dropped.