5,303 karma · joined October 24, 2013
Web http://socsci.uci.edu/~rfutrell/ Twitter @rljfutrell
It looks convincing to me. It's exactly the same method used to decipher cuneiform, starting with proper names in certain inscriptions and then figuring out the content of other inscriptions somewhat like a crossword puzzle. The fact that one of the tablets turns out to record the syllabary in order is especially compelling.
Thanks for your feedback. I think our manipulations do establish that there are nontrivial inductive biases in Transformer language models and that these inductive biases are aligned with human language in important ways. There's no universal a priori sense in which Moro's linear counting languages are "simple" but our deterministically shuffled languages aren't. It seems that GPT language models do favor real language over the perturbed ones, and this shows that they have a simplicity bias which aligns with human language. This is remarkable, considering that the GPT architecture doesn't look like what one would expect based on existing linguistic theory.
Furthermore, this alignment is interesting even if it isn't perfect. I would be shocked in GPT language models happened to have inductive biases that perfectly match the structure of human language---why would they? But it is still worthwhile to probe what those inductive biases are and to compare them with what humans do. As a comparison, context-free grammars turned out to be an imperfect model of syntax, but the field of syntax benefited a lot from exploring them and their limits. Something similar is happening now with neural language models as models of language learning and processing, a very active research field. So I wouldn't say that neural language models can't shed any light on language simply because they're not a perfect match for a particular aspect of language.
As for using languages more directly based on the Moro experiments, we've discussed this extensively. There are nontrivial challenges in scaling those languages up to the point that you can have a realistic training set, where the control condition is a real language instead of a toy language, without introducing confounds of various kinds. We're open to suggestions. We've had very productive conversations with syntacticians about how to formulate new baselines in future work.
More generally our goal was to get formal linguists more interested in defining the impossible vs. possible language distinction more carefully, to the point that they can be used to test the inductive biases of neural models. It's not as simple as hierarchical vs. linear, since there are purely linear phenomena in syntax such as Closest Conjunct Agreement, and also morphophonological processes can act linearly across constituent boundaries, among other complications.
> The one language that you use that is most similar to the linear languages cited by Moro, "Hop", shows very little difference in performance, directly undermining your claimed refutation of Chomsky.
I wouldn't read much into the magnitude of the difference between NoHop and Hop, because the Hop transformation only affects a small number of sentences, and the perplexity metric is an average over sentences.
That's just the point we were making: if you mess with the structure of natural language, then language models don't learn it as well any more.
The transformations do preserve the entropy in the sense that the lowest achievable perplexity is the same for everything except the nondeterministic shuffle. Since applying a one-to-one function preserves the entropy of a discrete random variable, in this case the random variable over documents in the training and test sets. In principle, a universal approximator should be able to learn to invert any one-to-one transformation we apply, although of course in practice a GPT architecture doesn't achieve this.
The transformations do mess up the local entropy in strings. But I think that's part of the point. Human language seems to be structured in a way so that things are locally predictable. When you screw up that structure, then languages are harder to learn.
We are working on a followup with more transformations including syntactic ones, as you might imagine. It's surprisingly hard to come up with manipulations that target specific aspect of linguistic structure, while fitting the criteria that (1) they don't affect the lowest achievable perplexity, (2) they clearly change the language from "possible" to "impossible" in a way that all or most linguists would agree with, (3) they can actually be implemented using the data we have---for example a transformation that relies on detailed syntactic parses would require that we parse the whole dataset, which is not only time consuming but also introduces possible confounds from errors in the parser, etc. We're talking to a lot of people, if you have ideas we'd be happy to hear them!
As for tokenization, good point: it's worth retokenizing based on the altered datasets to see if that changes anything. I think it might not, because the tokenizers we use are based on the frequency distribution of "words" identified by whitespaces, but we'll have to check.
You can communicate and remember a lot orally. The Polynesian navigators encoded information about how to navigate from island to island in oral poems passed down generation to generation. A lot of these traditions seem to vanish once a culture gets writing, leaving it unclear how they used to pass on so much information before.
It did have cool skins.
The interesting thing is that in English this generally pushes you to put short phrases before long phrases, as described in the article, but in languages with other word orders you can get the opposite effect. For example in Japanese the verb is always the last thing in a sentence, and so the way to keep related words together is actually to put long phrases before short phrases. So you'll often get sentences with structures like [[very long object] [short subject] verb].
The real breakthrough was Kepler, who dropped the idea that planets moved in circles. It was indeed partly a mathematical breakthrough and the reason Kepler's work took a while to catch on is that people couldn't understand his math at first. But it was also empirical, as Kepler had access to new and much more precise observational data collected by his mentor Tycho Brahe.