The more I dive into the task of high quality machine translation the more I get annoyed about the standards by which the machine translation are measured. For those who don't know, the quality of machine translation is solely measured on how well the system can recreate a translation made by human translators. Fair enough, if the machine comes up with the same translation as professional translator we can say it has done a marvelous job indeed. Except if maybe translator made a mistake. But that's not all, a job of translator, a professional one who makes high quality translations at the very least, is to translate content to target audience so they can read it. This can often mean adding new data to fill in the audience of facts that perhaps the audience of source language text know better, a machine coming up with that will be a smart machine indeed, but I don't see that happening. Human translators can also drop a lot of words when it's too wordy, e.g. certain ways of saying stuff in English will almost sound like you're explaining things to a child in Finnish if you take too exact translations, but again, a machine smart enough to realise that is not what I foresee in the near future. And then there's a lot of rewording, humans will kind of know when you want to translate verbs into nouns and reword whole sentence cause the way of expressing things is kind of weird for this language, well the machine that realises this may be plausible, in fact, if we just throw enough data to a statistical system it will realise that the sentence is odd, and may have seen the rewording.
The reason why I'm writing this is, I finally for the first time took a serious look at the data that is used to measure the quality of machine translation, that is the europarl stuff. The vast majority of it is horrifying, to the extent that I as human cannot even begin to explain how, if you are given this English sentence can you come up with anything distantly resembling that Finnish sentence, or even matching up with say half of the words in it. If I cannot explain the translation it is at least obvious that we cannot build a rule-based system to map between these two, but even with statistics to be able to learn that, say, if you are talking of tv channels shown in the hotels of members of European parliament and specifically a tv channel named FOO, and English text doesn't give any details of the channel, you are expected to translate FOO as FOO, this is a dutch tv channel broadcasting mainly news, what kind of statistics would really give you good evidence of doing that is rather weird, but not getting that right will probably reduce your score for that translation to 0! While that specific example is not in europarl hopefully, there is a session that is about tv channels and there are a lot of cases like that all over, and indeed machine translation is tasked on finding a way to create algorithms that would faithfully reproduce that kind of rewordings and additions, it's whole lot of nonsense how the systems are evaluated really.
So, machine translation IMO is never particularly suited for much of paraphrasing, rewording, adding information or that sorts of task, moreover we should really concentrate on making systems that a) faithfully carry the information across to the reader as it is and only then b) make it sound like it is grammatically correct and colloquial in target language. Trying to optimise systems to make all these high quality rephrasings and stuff is really a foolish goal to have, rather than to just make sure that the systems are good at not losing any information nor inverting any meanings, which is the biggest problem as I see with current system mainly caused by the fact that they are trying to solve this all at once. Like, who cares if English is more likely to say "don't forget to frobble" where Finnish speakers would go "remember to frobble", but with the current scoring system we do get penalised hugely for not getting that right, and perhaps, getting the common statistical machine mistranslation "don't remember to frobble", oh, it gives us more points of course! So that's what we're optimising our system for. Sweet.
By the way did I mention that if we'd score professional translators by the same measures we use for machine translation they would usually get scores that we deem so low that they're not worth of publishing. Yeah, ain't that a good measure.
Yeah yeah, so this is not specific to machine translation but all computational linguistics in its glory, this madness follows us anywhere we go it does. It is a good thing that we want to systematically measure how well we're doing, instead of just throwing random things at random ad hoc implementations of stuff and writing 5 page essays for conferences describing why things got better with stuff, but it is indeed an exercise in futility when things go towards the trying to recreate bugs or mistakes just because. This is the case of most things like so-called morphological analysis, there are no good standards or metrics on it, so whoever writes the first "gold standard", which in morphology will either mean just a dump of some systems output with systematic errors and all, or another choice is to actually have human annotators do the standard, which may be slightly better. Unfortunately the big mistake here is that people doing linguistics don't really understand how things work, e.g., how to really really prove that analysis is correct and there's some measurable evidence that proves it, but the way human annotators work is just by intuition, And so we end often enough with the enjoyable task of reproducing either bugs of another system or linguistic intuition.
In conclusion, all the millions of money that is spent on computational linguistics, most of it goes in engineering aimed at reproducing bugs and mistakes faithfully, your money at work, isn't it.
This blog is a private web log of Flammie, it is mostly work-related however. Computational linguistics is the topic. Some conference musings as well as notes about working in uni as developer for our field / researcher.
Näytetään tekstit, joissa on tunniste machine translation. Näytä kaikki tekstit
Näytetään tekstit, joissa on tunniste machine translation. Näytä kaikki tekstit
perjantai 31. lokakuuta 2014
keskiviikko 17. syyskuuta 2014
Translation machines
In machine translation there's usually ongoing some sort of a competition or disagreement between statistical and knowledge-based approaches. Statistics is based on a logic that if you have a lot of good quality material and you push it through the machine it creates even better quality material from the best bits and makes it more usable. Like a meat grinder. However that rarely happens so that the source material is actually as good quality as anyone would assume. The primary source of machine translations is europarl, a corpus of European parliament sessions transcribed and translated, and the that is trained on that can merely recall what it's seen there, statistical machine translation, you see, cannot make very good creative decisions, it can in fact only remake same decisions it has seen in translations fed to it. So giving such machine translation text that is not European parliament session it usually fails to make good connections. Much like this McDonalds' meat substitute here:
In knowledge-based, linguistic or rule-based machine translation there's an opposite problem. The people working on knowledge are interested mainly in looking at very small amount of data, the gold or the crown jewels of the language are what is interesting, neglecting the uninteresting words and stuff that makes up 95 % of good machine translation. Further problem is that their jewels aren't truly precious but fakes, that is, the interestingness is based on old misclassifications that they hold on to, to make problems more interesting, such as fake ambiguity made by wrong classifications. So they end up working like these guys from South Park.
maanantai 23. kesäkuuta 2014
To end the science festival season: EAMT 2014
With absolutely ovewhelmingly too many conferences and too little to blog about, EAMT was my first MT conference now. We were in Dubrovnik, nice touristy city, too much sea food, quite a bit of rain. Anyways, I would've thinked something like EAMT would be relatively large, given things like EACL are too, but it was single track event, with manageable amount of people. Our PR team already wrote about official side of things in CNGL blog post of EAMT 2014 (how weird is that to have someone to work on that kind of stuff in academia, eh?). There's the thing that I said there that I think is indeed one of the main goals for my research, the end user applications we know are quite doable and have seemed like science fiction since 50's but we still aren't there and the reason isn't quite clear. We have our machine translation chains, with or without analysers, OCR, speech recognition, TTS, there's no reason we shouldn't have mobiles that can read your foreign food menus and translate them, listen to server and you interpret between you the whole interaction–we have all this and in reasonable quality as well, it's not sci-fi anymore. I know I travel a lot and while I make an effort to learn basics of languages* as I go, I would much enjoy such app. So we'll try to have one. Now the problem with this is, all machine translation systems are built to understand and translate only documents of European parliament, so they fail when they see non-prose texts like food menus. Even though translating menus and ingredients would be easier. And interaction with waiters too. No sentence structures, just words and some phrases you know. Should think about building for that, hmm.
Tunnisteet:
conference,
eamt,
machine translation,
pizzur,
smt
Tilaa:
Blogitekstit (Atom)