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Yes exactly, I fear that shortening the training time would skew the results. In the very short term, smaller batch size is typically better just because you need a certain amount of gradient updates to move away from the original random, hence pretty terrible, weight distribution. Larger batch size gives a steadier, but slower, convergence, so it's hard to say for sure what is better for a given compute budget.

I'm definitely _not_ encouraging you on spending more money on a side topic just for the sake of optimizing this one parameter, there will always be another parameter after that that you'll feel an urge to optimize :-) I'd say it's already a pretty neat result to have come to a very close score to the original GPT2 training starting from scratch!

P.S. If you want to push it a bit further, rather than optimizing parameters for this model, last week at EurIPS I heard that a current "very good" modern repo to start from in order to train a good LLM is this: https://github.com/Niccolo-Ajroldi/plainLM. I haven't investigated this exactly (I'm not working on LLM), but it might be interesting to you for a sample run. The (N)EurIPS paper that was discussed at the conference claimed that the only important change to do was to modify the hyperparameters of the Adam optimizer, setting beta1=beta2=0.95 for example (the default values are beta1=0.9 and beta2=0.999 which are apparently outdated).

Sorry came a bit late to this reply. Interesting, well, nobody says it's a monotonic function :-) in the limit of _very_ large batches you of course are worse off, because you take a very large amount of computation before taking a single step, so if you stop after a fixed amount of time your model just didn't have the time to learn properly. So certainly there is a sweet spot somewhere.

I suppose, the real "function" is a bit more complicated because (1) If you put 2x more data through the same GPU with large enough memory, it will take less than 2x the time to compute (but certainly not 1x). (2) At some point, empirically, increasing batch size makes it _worse_ even if you ignore the additional runtime cost (i.e. stop after n gradient update steps, and not x seconds). To my knowledge, the accepted reason for that fact is that a bit of noise helps in regularizing learning, because overly smooth learning curves end up stagnating in local loss minima more easily. In truth, I think nobody exactly understand how deep learning models work :-)

And to your other question - sorry again for the late answer. Yes, `optimizer.zero_grad()` should always be called directly after `optimizer.step()`, therefore with gradient accumulation once every `n` steps (otherwise, you'd be zeroing out the gradients, so just throwing away all the compute you did in previous steps).

Sorry I just opened that file now, and browsed through it very quickly, but my eye fell on the excerpt: ``` However, we did not observe any speedup by increasing the batch size from 65536 to 131072 for the first stage, thus, we restrict the batch size to 65536 for this stage. ``` which I think is more or less my point: increasing batch size essentially always helps, but the speedup reduces the more you push the batch size. Provided that your dataset is large enough, more batch size will always make you run a bit faster without sacrificing accuracy, but the speedup will be less and less as you increase the batch size, until you are anyway maxing out the power of your GPU and you can't see any measurable speedup anymore.

Mmh not really. As OP shows, speed increases with larger batch size, but only initially, until the GPU has high enough utilization; then speed improvements flatten out (although you might get OOM before that and not "really" see the flat part). Using smaller batch size increases _noise_, so quite literally decreases stability. That might be good sometimes: in the limit case, if the batch is as large as your training set, you'll end up in local minima and not be able to get out of it. But this is true for toy datasets like MNIST, here it's an entirely different beast.

With such large corpora as the ones used here, and very noisy ones at that, gradient updates are very noisy and that can harm quality. Or anyway, common lore is that one needs pretty large batch size to have the language model improve steadily.

Thanks, very nice to see these results! Certainly using GPUs with more RAM makes things simpler to scale. Gradient accumulation is as easy as adding a counter for number of steps and an "if counter % gradient_accumulation_steps:` around `optimizer.step()`, so that can also be tried simply on a single GPU / cheaper GPUs. But if you can just use 8xA100 and your pipeline parallizes well, you also get results (almost) 8 times faster, which is certainly nicer to experiment of course!

A separate comment about conclusions about why they are worse than OpenAI GPT2 - which to me feel to be missing the point.

One main point is batch size - I'd agree with Gemini here. Batch size <= 5 with 1024 seq len is really tiny. Nowadays models are trained with effective batch size of millions of tokens in total. Of course, this won't fit into memory, one uses gradient accumulations to that purpose, again as mentioned by Gemini.

Training duration is definitely also a reason - models do get better over time, otherwise people wouldn't train so long wasting millions :-) just how long for optimality is unclear, but certainly < 2 days is not optimal even at this "small" scale.

The optimizer could also play a role. As the author mentions, a fixed learning rate is hardly optimal, it is typically both increased in the beginning ("warm up", but that's for stability, if training works without, that's not an issue) and scaled down at the end ("cool down" - that is, annealing, with cosine as mentioned in the article). This generally squeezes out a bit more performance. Also, while it's true that dropout was used back then (might be useful for many epochs, likely only harmful for < 1 epoch), using _both_ dropout _and_ weight_decay > 0, as the author does, is probably wrong and makes training too slow & careful to get good results. Also, even if used, a "good" implementation of weight decay should skip some layers like embeddings and biases (GPT2 did that, and it's relatively important to do so).

On the other hand, I'm pretty sure that using mixed precision and TF32 has absolutely no downsides. It's really standard nowadays to use either mixed precision (FP16 gradients + FP32 base weights) or directly BF16 ("brain" float 16, a bit like the TF32 described there, but with only 16 bits) and I have almost never seen either one fail... and when it does, it typically fails spectacularly, with NaN losses or the model degenerating to trivial performance.

This is a very nice, detailed post! I have a few minor comments though (maybe a few are discussed somewhere, it's a _long_ article and I can't claim 100% coverage :-) ):

Calling it "training LLM" is a bit misleading. This is a small GPT-2-sized model (~160M params), while the "L" in "LLM" stands for large...

The early discussion and worries about truncating strings look a bit weird. The author then realizes they're anyway not even going to use 30% of the total available data, so who cares if for each given string we're only using the first 1024 tokens? (And anyway, even if doing more epochs, he doesn't discuss the obvious solution to avoid throwing away data, i.e. not clipping always the tail but starting from a random point each epoch - maybe after a punctuation or something)

At this level of simplicity, setting up a validation loop might be an unneeded complication (for the autoregressive pretraining part, not the instruction-tuning of course). That's because anyway the model is training for < 1 epoch, so no data is seen twice (*). One might as well just track the training loss, it's slightly less "clean" because it's evaluated each time on different data, but the sheer size of it makes up for the issue. The final plot shows that the two curves are similar - train is noisier of course, but nothing a bit of rolling smoothing couldn't solve.

The choice to load all tokenized text into RAM feels odd... it works, and it's possibly slightly faster than loading on-the-fly, but only if you have enough RAM to "waste". PyTorch loads data on separate processes in a non-blocking way, so it feels like having it on disk and loaded on-the-fly would be safer and not make any hit on runtime. But well, if it fits, it's certainly easier that way (although, as the author remarks, it only works if you can store it as a numpy array or torch tensor of some internally supported dtypes like int or float; if they are any Python "object" types, they get replicated per dataloader worker, and OOM is guaranteed)

The choice to concatenate everything into a long string is a bit outdated nowadays. Because it trains with attention between different sentences that have nothing to do with each other, and could cause a bias or anyway suboptimal results. Nowadays people use masked attention ("document masking"), which is so popular it's even supported by FlashAttention: https://github.com/Dao-AILab/flash-attention/issues/654

(*) Of course, the data is dirty enough that there _will_ be some duplicated stuff here or there, but the same is true for a random train/validation split. Also such a small model would have very little risk to memorize, even if some data were replicated.*

Aside from the weirdness of calling "good old" something that was released 17 months ago :-D I mean, deep learning is evolving at crazy rhythm, but you just can't assume a good paper gets written in days.

That said, as others have pointed out, and as it's also written on the blog post, they are entirely different methods. QLoRA requires access to the full training data, while theoretically you can apply SpinQuant to any given model. For example, they also apply it to Mistral, not only to their LLaMA.

(QLoRA also takes some time and compute to apply, but since SpinQuant also implies learning some weights, I don't know if it's actually faster/cheaper, too)

I know nothing about what makes an industry succeed or fail, and also nothing about web tech, but working in the field I can comment on:

> tensorflow looks like currently loosing to pytorch - seems like google got bored and more development is for JAX, Keras wrapper

Well, TensorFlow doesn't "look like currently losing", it has already lost since a long time. I haven't seen a decent paper release code in TensorFlow in years, and all the references I see to TF online are job posts from "older" companies (to the point that, if you are looking for a job in data science, seeing TF mentioned in the job post is kind of a red flag of a place you don't want to be).

That said, I am quite certain that this has only a small impact on why Google is losing terrain, and even on why it is behind in AI (which is also debatable: narrative aside, Gemini is not that much lacking behind competitors). Certainly if TensorFlow + TPUs turned out to be better than PyTorch + GPUs they would have had a lead to start from, but if that was so important, Meta or NVIDIA would have created the first LLM, not OpenAI.

Simply, sometimes stuff happens, you can't predict it all.

I know this is HN and here it's not a popular opinion, but maximum security is _not_ always a good idea. Even setting aside the problem of many different actors having to access these details mentioned below, there's value in a simple login process. Specifically for airplane tickets, the most common ones I had to struggle with multiple times are retrieving reservations bought from a different computer, or by a travel agency. In all these situations, it was exactly the simple approach that saved me. If 2FA was mandatory, the best case scenario was that the travel agency would have to send you a separate e-mail with details about how to access their portal where this 2FA would somehow work. The number of systems multiplies, the number of credentials to remember does, as well. If you are not from your usual workplace (and chances are, if you are travelling, you are not) or from a shaky connection (same), you are in a real problem. In a time-critical scenario, which makes it really worse.

Implementing a "secure" connection here would be a sure road for pain ahead, at least it would need the airplane company to increase customer support a lot, and likely a lot of bad publicity every time something fails. Delays cost money, especially in this industry. And what would you get for that? The safety that, if you publish a picture of your reservation / boarding pass online, nobody can log in with your credentials and cancel your flight? That's a rather niche and very targeted risk, which is better handled by a single customer support agent who, simply, issues you a new ticket.

(by the way, by the time you have checked in and your boarding pass has been issued, a lot of companies just don't allow you to cancel anymore, so it's really a non-issue?)

Do you have sources for "The MFU can be above 40% and certainly well above the 35 % in the estimate"?

Looking at [1], the authors there claim that their improvements were needed to push BERT training beyond 30% MFU, and that the "default" training only reaches 10%. Certainly numbers don't translate exactly, it might well be that with a different stack, model, etc., it is easier to surpass, but 35% doesn't seem like a terribly off estimate to me. Especially so if you are training a whole suite of different models (with different parameters, sizes, etc.) so you can't realistically optimize all of them.

It might be that the real estimate is around 40% instead of the 35% used here (frankly it might be that it is 30% or less, for that matter), but I would doubt it's so high as to make the estimates in this blog post terribly off, and I would doubt even more that you can get that "also for small models with plain pytorch and trivial tuning".

[1] https://www.databricks.com/blog/mosaicbert

I'm into AI but not into sound, so I might be saying something stupid here, but I think using something like this for very high volume like concerts would be possibly outright impossible, but, even if not, certainly quite dangerous and therefore not commercializable.

My understanding is that to "mute" a sound, you need to inject another wave that is exactly the opposite, with the exact same volume and in perfect sync, so that the two waves interfere destructively. However, in general but especially in AI, you can never guarantee 100% accuracy. If you use this technology to "silence" a background fountain, and something goes wrong, at worst you get a lot of noise that make you grimace and remove them. If at a concert with 100+ dB of music you get an error and your headphones start producing a similarly loud, but not perfectly aligned noise right into your ears, you probably won't have the time to remove them before damaging your hearing system.

In general, I think that having a tool that drives 100+ dB straight into your head is probably not a wise idea :-)

Yep that also sounded weird to me. I had, IIRC, three of my wisdom teeth removed as a teenager, I was living in Italy back then. I think two of them in a single session. General anaesthesia wasn't even an option, the whole thing happened in a normal dentist cabinet with a local anaesthesia to the relevant half of the mouth. I distinctly recall the dentist complaining that for one of the teeth my roots were particularly strongly attached to the bone, and he had to push and lean on it, _hard_; it didn't really feel painful, except that my jaw was aching on the opposite side (the mostly-non-sedated one) due to the pressure he put on it.

In fact, I think people and doctors alike tend to sedate much less in Italy - maybe not completely unjustified from a few things I've read in this thread. Back then, the normal drilling & filling tooth cavities mostly happened without any anaesthesia at all, local or otherwise. Frankly, that was quite painful, whenever the drilling happened to touch a nerve, and I really don't feel like experiencing it again :-) and I think at least this changed since.

Variety matters a lot. If you pay 1000 trained labellers, you get 1000 POVs for a good amount of money, and likely can't even think of 1000 good questions to have them ask. If you let 1000000 people give you feedback on random topics for free, and then pay 100 trained people to go through all of that and only retain the most useful 1%, you get much ten times more variety for a tenth of the cost.

Of course numbers are pretty random, but it's just to give an idea of how these things scale. This is my experience from my company's own internal -deep learning but not LLM- models to train which we had to buy data instead of collecting it. If you can't tap into data "from the wild" -in our case, for legal reason- you can still get enough data (if measured in GB), but it's depressingly more repetitive, and that's not quite the same thing when you want to generalize.

If climate change were visible at that scale (tiny resolution between 0 and 40 degrees) we'd be all boiled since a while.

Still, you can see signs: the maximum temperature until 1990 or so seems to be around 35 degrees, since then there are several peaks above that value and in 2016 (?) it looks to be 38-39. It's certainly less visible on the peaks in the low, because maybe the absolute lowest scores appear to be in the 1990-2000 decade, but then again, all years in the 2010-2020 decade seem to be slightly higher than the minimum temperature in any other decade.

That said, there is massive downscaling involved in such scale, so I wouldn't be too surprised if some details were just skipped and not visible. I wouldn't trust this interpretation much - if a visualization it needs to be, I'd rather plot a moving average with a window of 6 months at least (or even 1 year to entirely rule seasonalities out), and see if that one has an upward trend or not (I bet it does).

[EDIT] I now see the post below with the year averages since 1979. It does indeed seem that 1995-1997 were abnormally cold years, and also that 2010-2020 is the warmest decade since then (and likely since quite a bit longer). So the outliers analysis here above seem to stand :-)

IIRC, GPT-4 would actually be a bit _smaller_ to visualize than GPT3. Details are not public, but from the leaks GPT-4 (at least, some by-now old version of it) was a mixture of expert, with every model having around 110B parameters [1]. So, while the total number of parameters is bigger than GPT-3 (1800B vs. 175B), it is "just" 16 copies of a smaller (110B) parameters model. So if you wanted to visualize it in any meaningful way, the plot wouldn't grow bigger - or it would, if you included all different experts, but they are just copies of the same architecture with different parameters, which is not all that useful for visualization purposes.

[1] https://medium.com/@daniellefranca96/gpt4-all-details-leaked...

Nothing to pardon, asking questions is always the right thing to do :-) I also didn't look into the paper in great details, although I'm quite sure I am not fooling myself, but still take this with a grain of salt.

My understanding is that this paper by MIT doesn't train any new model from scratch. I takes a pretrained model (e.g. StableDiffusion), which however is trained to do "a small step" only: you fix a number of steps (e.g. 1000 in the MIT paper), and ask the model to predict how to "enhance" an image by a certain step (e.g. of size 1/1000); the constants are adjusted so that, if the model is "perfect", you get from pure white noise to an image in the exact number of steps you set. If I remember correctly how diffusion works, in theory you could set this number to any value, including 1, but in practice you need several hundreds to get a good result, i.e. the original StableDiffusion model is only able to fit a small adjustment.

This new paper shows how to "distil" the original model (in this case, StableDiffusion) into another model. However, unlike typical distillation, which is used to compress a big model into a smaller one, in this case the distilled model is basically the same as the one you start with; but it has been trained with a different objective, namely to transform random noise to the prediction that the original model (StableDiffusion) would make in 1000 steps. To do so, it is trained on a very large amount of triples (text, noise, image). But I don't think you can incorporate into this training procedure other "real" images that are not generated by the model you start with, because you don't have a corresponding noise (abstractly, there is no such concept as "corresponding noise" to a given image, because the relation noise -> image depends on the specific model you start with, and this map is not anywhere near invertible, since not all images can be generated by StableDiffusion, or any other model).

Once the model is trained, you can of course give it a new prompt and, in theory, it should generate something rather similar to what StableDiffusion would generate with the same prompt (hopefully, the example displayed on their web page are not from the training set! Otherwise it would be totally useless). But you should never obtain something "totally different" from what StableDiffusion would give you, so in that sense it's not "general", it is "just" a model that imitates StableDiffusion very well while being much faster. Which is already great of course :-)

The weights are different, because the model is different.

As jzbontar below mentions, the crucial point is that the random noise mask is the same. The diffusion models are trained to turn random noise to an image, and they are deterministic at that - the same noise leads to the same image.

What the authors did here was to find a smart way of training a new model able to "simulate" in a single step what diffusion achieves in many; to do so, they took many triplets of (prompt, noise, image) generated starting from random noise and a (fixed) pretrained stable diffusion checkpoint. The model is trained to replicate the results.

So, it is surprising that this works at all at creating meaningful images, but it would be _really_ surprising (i.e. probably impossible) if it generated meaningful images which were seriously different from the ones it was pretrained with!

I suppose varying the neural net size wouldn't be the best way of doing that; very small nets can have very "unhuman-like" behaviour. I'm not an expert on reinforcement learning, but for other fields in deep learning that's typically the case.

I think that, to simulate worse human-like players, it would be better to just increase the temperature: don't always select the best move, at every step just select one of the top 10, randomly proportional to some function of the model-predicted probability of it being "the best" move (e.g. a power of the probability; very large powers give always the best move, i.e. the strongest player, and powers close to 0 tend to choose uniformly at random, i.e. the weakest player). The only thing I'm not certain about is, if you train the original network well enough, stupid blunders (that a very bad human player like me would make) are still scored so low that there's no way this algorithm will pick them up - the only way to know would be to try.

Sharing my experience here. My background is in math (Ph.D. and a couple of postdoc years) before switching to practitioner in deep learning. This year I taught a class at university (as invited prof) in deep learning for students doing a masters in math and statistics (but with some programming knowledge, too).

I tried to present concepts in an as reasonably accurate mathematical way as possible, and in the end I cut through a lot of math in part to avoid the heavy notation which seems to be present in this book (and in part to make sure students could spend what they learnt in the industry). My actual classes had way more code than formulas.

If you want to write everything very accurately, things get messy, quickly. Finding a good notation for new concepts in math is very hard, something that gets sometimes done by bright minds only, even though afterwards everybody recognizes it was “clear” (think about Einstein notation, Feynman diagrams, etc., or even just matrix notation, which Gauss was unaware of). If you just take domain A and write in notations from domain B, it’s hard to get something useful (translating quantum mechanics to math with C* algebras and co. was a big endeavour, still an open research field to some extent).

So I’ll disagree with some of the comments below and claim that the effort of writing down this book was huge but probably scarcely useful. Who can read comfortably these equations probably won’t need them (if you know what an affine transformation is, you hardly need to see all its ijkl indices written down explicitly for a 4-dimensional tensor), and the others will just be scared off. There might be a middle ground where it helps some, but at least I haven’t encountered such people…

I guess I should be wiser than contradicting LeCun on a public forum, but his math doesn't really work out. It only works if there is a unique correct answer to any question, in which case e=1/dict_size which is clearly false - even humans can just put "Let me think..." in front of anything else and get logically "the same" answer; after how many such filler words do you deem it "wrong"? Even taking colloquial speech aside, in Math, there is apparently a book that collects 367 different proofs of the Pythagorean Theorem; that tree of correct answers is certainly quite complicated. You can't approximate it with a fixed probability and take the exponential - the number of possibly correct next tokens varies very strongly depending on the previous string.

LLMs and autoregression are very good at avoiding the 99.999[...]% of the strings that are simple gibberish. If you were to generate a string made of 20 random tokens from GPT2 tokenizer, you would get something like:

"automakersGrand carries liberties Occupations ongoingOULDessing heartbeat Pillar intrigued Trotskymediatelyearable founding examinations lavAg redesign folds"

and of course any half decent language model does much better than that. If the "paths to truth" were as unlikely as LeCun puts it there would be no hope.

A non-autoregressive model would certainly be "better" because it would be faster, which is where language models started from (BERT & co.), it just doesn't seem to work as well... similarly to how a human sometimes needs to write something down and only realizes the correct answer to a complicated question on the go.

If anything, we'd need to allow LLMs to realize mistakes and correct themselves out of them, i.e. making the generation non-linear. If you ask GPT4 something complicated (like math) it's not rare at all that it logically contradicts itself in their answers. I would be surprised if, somewhere deep in the model, it doesn't "realize" this, but it can't fix it, so it falls back to what humans do at an exam or interview that started badly: try to bullshit their way out of the thing, sweeping the inconsistency under the carpet, unless you explicitly point it to them (and often even after that, both GPT4 and humans).

P.S. Mathematician rant: who on Earth calls a probability "e"??

(I'm also replying myself concerning the problem itself).

Unless I'm getting myself completely wrong, this also seems to be a very unusually simple problem for IMO's standards. I don't think I ever got myself solving one of them when I tried in the past, but if I'm not fooling myself the most natural approach for this one seems to bring to the solution:

1) Look at the two smallest divisors 1 < d_2 < d_3 of n. Then d_2 is necessarily a prime p, and d_3 is either p^2 or a different prime q. Let's first prove the latter can't be the case: if it where, looking at the biggest 3 divisors [n/q, n/p, n], we'd get that there's an integer a such that: n/q * a = n/p + n. Simplifying a bit, we get (1+p)q = ap, which is impossible because p divides neither p+1 nor q.

2) So, for n not to be a power of p, it must be 1 < d_2=p < d_3=p^2 < ... d_{k+1}=p^k < q. In particular, p^{k-1} must divide p^k+q. However this is also impossible, because p^{k-1} obviously divides p^k, but not q, so it can't divide the sum.

Gosh I feel like a grumpy old man saying "those youngsters, on my days we used to have harder problems than this" ;-)

Good to know it can do that, in the pasted chat above it didn't. To be honest, it surprised me it couldn't, this isn't exactly a very hard guess given the computation results. It doesn't convince me GPT4 is anywhere close to winning the IMO, though :-)

A decent start? It says absolutely nothing about how to solve it, except repeating the question. The part where it tries out the few first numbers is entirely wrong, given that 6 does _not_ satisfy the condition (2 does not divide 3+6=9) and 8 _does_ (2 does divide 4+8=12).

Amusingly, the list of the integers <= 100 satisfying the property is correct, and it contradicts itself from the previous paragraph. Maybe if GPT wasn't a one-directional autoregressive model but allowed itself to go back and edit the past, it would have caught up that discrepancy and fixed it - but no such architecture currently exists that would run in decent amount of time.

Given that GPT4 is not a model but a full product, behind the scenes it probably coded up and ran a small python code that translated the problem into code, executed it and got its solution for the first few integers. Which would be a good thing to do to start solving a problem like this, except you're not allowed to do that at the IMO, obviously.

Looking at the output of this program, it suggests that powers of primes could be a class of solution (or maybe even the only solutions? I guess that's all the problem was _really_ asking to prove, but having never qualified for the IMO myself, I can't be sure). In fact, for n = p^k, the divisors are [1, p, p^2, ..., p^{k-1}, p^k], and clearly always p^i divides p^{i+1} + p^{i+2} = p^i (p + p^2). I guess this small remark would have gained me a point at the IMO, only 41 to go ;-)

But the other side of the coin is that having those numbers written down in front of you and not even making a conjecture about powers of prime being the answer would really denote poor mathematical reasoning by GPT4. It's only really proving that it can understand what it's being asked, which, I admit, places it in a better position than maybe 90% of the human population, but unfortunately for GPT4 mathematics is the least democratic science of them all - it's always only the top-1 result that matters in the end.

P.S. Being a former mathematician currently working on deep learning, having (or building!) a model that can solve mathematical questions has always been my dream. I'm not even talking about something that can _prove_ things, even just that can understand and rephrase them in different settings (which in mathematics is very, very hard, even for a human). Or spot weaknesses in already stated down proofs. As a graduate student, having something I could chat about to ask silly question while studying a paper would have been a real game changer. Even for best-of-world professionals it would be useful: when the wrong proof about the ABC conjecture came out, it took months of work from the best minds of our world to read through it and disprove it. If Mochizuki had had some tool for automatically checking his proof (and a smaller ego, I guess) he could have caught that early on, saved everybody a lot of work and the whole world some useless drama.

And while we're closer than ever to reaching that, I think GPT4 is still quite a far way from it. But with the pace we've seen recently in AI evolution, who knows...

Well, nuclear power is literally the reason why in this map: https://app.electricitymaps.com/map France is almost constantly green, while Germany, Poland, and most of the US, are just different shades of brown...

Are you implying that if there was no Nuclear plant in Fukushima, the Tsunami would not have happened, or the people living there wouldn't have been needed to be evacuated?

I've worked in two companies in Germany and, unless I'm wrong, both of them had 6 months periods for Senior position. At least the second one has no problem retaining good staff.

As several others mention here, this is mostly on paper only. In both companies I've seen people leaving with any amount of notice, between 1 and 6 months. You just asked your manager and, if you have decent relationship, you'd get an okay. If you didn't, there's really no reason for them to keep you doing nothing (which, at that point, is almost a given). The only real risk is if you have a really bad manager who wants to "punish" you for leaving, even if this is at detriment of everybody involved.

At least if the company from the OP is a very large one, I wouldn't assume it to be a red flag, but rather bet on the company having an overdeveloped bureaucracy department, who created central contracts who-knows-why and won't change them even though the practice is always different.

Yes of course, sorry my write-up was confusing: I meant that "adding a ReLU between the two linear layers" (the second option) would result in more parameters than "directly removing the second linear layer" (the first option). And my message just meant "I don't know which of the two options achieves the best trade-off between speed and quality". I didn't consider the option "leave it as it is in the blog post" because it is essentially equivalent to the first option (removing the linear layer) but slower (as you say, with exactly the same number of parameters as the second option), so it definitely shouldn't be a "best" option.

Well it depends what you mean by “best” :-) removing the linear layer is the easiest solution (indeed you can’t remove the embedding one; in theory you could replace embedding + linear by one hot encoding + linear, adapting the input dimension or the linear layer to match your vocabulary size, but that would just be identical to embedding layer, just much slower and more memory hungry).

Alternatively, you could indeed put a ReLU or other non linearity between embedding and linear, you get a different model with more layers and more parameters, as the given dataset is pretty large I’m quite sure this would bring an improvement to accuracy, but without testing it’s rather impossible to know. Normalisation also acts as some kind of non linearity, but when the author adds it that barely helps accuracy at all, so who knows, sometimes (often) neural networks are counter intuitive…

Kudos for the work! Stupid comment (not really on the main topic of the blogpost, but might be useful anyway for future "toy example" models): in the initial SimpleBrokenModel class [EDIT: and also in SimpleModel), there is actually quite a bit of wasted computation (something like > 66% of all the model computations!). You are applying, in sequence, the following layers:

- embedding 65 -> 128

- linear 128 -> 128

- ReLU

- linear 128 -> 65

But since there's no non-linearity at all between the first two layers, and they both are linear... the second one is totally useless. This model is effectively a "classical" single hidden layer MLP. And in terms of FLOPS, it's wasting 128128=16k operations out of a total of 128128+65*128=24k operations.