Free courses at Kaggle

I recently found out that Kaggle has a set of free courses for learning AI skills.

Screenshot from Kaggle.com

The first course is an introduction to Python, and these are the course modules:

  1. Hello, Python: A quick introduction to Python syntax, variable assignment, and numbers
  2. Functions and Getting Help: Calling functions and defining our own, and using Python’s builtin documentation
  3. Booleans and Conditionals: Using booleans for branching logic
  4. Lists: Lists and the things you can do with them. Includes indexing, slicing and mutating
  5. Loops and List Comprehensions: For and while loops, and a much-loved Python feature: list comprehensions
  6. Strings and Dictionaries: Working with strings and dictionaries, two fundamental Python data types
  7. Working with External Libraries: Imports, operator overloading, and survival tips for venturing into the world of external libraries

Even though I’m an intermediate Python coder, I skimmed all the materials and completed the seven problem sets to see how they are teaching Python. The problems were challenging but reasonable, but the module on functions is not going to suffice for anyone who has little prior experience with programming languages. I see this in a lot of so-called introductory materials — functions are glossed over with some ready-made examples, and then learners have no clue how returns work, or arguments, etc.

At the end of the course, the learner is encouraged to join a Kaggle competition using the Titanic passengers dataset. However, the learner is hardly prepared to analyze the Titanic data at this point, so really this is just an introduction to how to use files provided in a competition, name your notebook, save your work, and submit multiple attempts. The tutorial gives you all the code to run a basic model with the data, so it’s really more a demo than a tutorial.

My main interest is in the machine learning course, which I’ll begin looking at today.

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Rules and ethics for use of AI by governments

The governments of British Columbia and Yukon, in Canada, have jointly issued a report (June 2021) about ethical use of AI in the public sector. It’s interesting to me as it covers issues of privacy and fairness, and in particular, the rights of people to question decisions derived from AI systems. The report notes that the public increasingly expects services provided by governments to be as fast and as personalized as services provided by online platforms such as Amazon — and this leads or will lead to increasing adoption of AI systems to aid in delivery of government services to members of the public.

The report’s concluding recommendations (pages 47–48) cover eight points (edited):

  1. Establish guiding principles for AI use: “Each public authority should make a public commitment to guiding principles for the use of AI that incorporate transparency, accountability, legality, procedural fairness and protection of privacy.”
  2. Inform the public: “If an ADS [automated decision system] is used to make a decision about an individual, public authorities must notify and describe how that system operates to the individual in a way that is understandable.”
  3. Provide human accountability: “Identify individuals within the public authority who are responsible for engineering, maintaining, and overseeing the design, operation, testing and updating of any ADS.”
  4. Ensure that auditing and transparency are possible: “All ADS should include robust and open auditing functionality with enhanced transparency measures for closed-source, proprietary datasets used to develop and update any ADS.”
  5. Protect privacy of individuals: “Wherever possible, public authorities should use synthetic or de-identified data in any ADS.” See synthetic data definition, below.
  6. Build capacity and increase education (for understanding of AI): This point covers “public education initiatives to improve general knowledge of the impact of AI and other emerging technologies on the public, on organizations that serve the public,” etc.; “subject-matter knowledge and expertise on AI across government ministries”; “knowledge sharing and expertise between government and AI developers and vendors”; development of “open-source, high-quality data sets for training and testing ADS”; “ongoing training of ADS administrators” within government agencies.
  7. Amend privacy legislation to include: “an Artificial Intelligence Fairness and Privacy Impact Assessment for all existing and future AI programs”; “the right to notification that ADS is used, an explanation of the reasons and criteria used, and the ability to object to the use of ADS”; “explicit inclusion of service providers to the same obligations as public authorities”; “stronger enforcement powers in both the public and private sector …”; “special rules or restrictions for the processing of highly sensitive information by ADS”; “shorter legislative review periods of 4 years.”
  8. Review legislation to make sure “oversight bodies are able to review AIFPIAs [see item 7 above] and conduct investigations regarding the use of ADS alone or in collaboration with other oversight bodies.”

Synthetic data is defined (on page 51) as: “A type of anonymized data used as a filter for information that would otherwise compromise the confidentiality of certain aspects of data. Personal information is removed by a process of synthesis, ensuring the data retains its statistical significance. To create synthetic data, techniques from both the fields of cryptography and statistics are used to render data safe against current re-identification attacks.”

The report uses the term automated decision systems (ADS) in view of the Government of Canada’s Directive on Automated Decision Making, which defines them as: “Any technology that either assists or replaces the judgement of human decision-makers.”

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Book notes: Hello World, by Hannah Fry

I finished reading this book back in April, and I’d like to revisit it before I read a couple of new books I just got. This was published in 2018, but that’s no detriment. The author, Hannah Fry, is a “mathematician, science presenter and all-round badass,” according to her website. She’s also a professor at University College London. Her bio at UCL says: “She was trained as a mathematician with a first degree in mathematics and theoretical physics, followed by a PhD in fluid dynamics.”

The complete title, Hello World: Being Human in the Age of Algorithms, doesn’t sound like this is a book about artificial intelligence. She refers to control, and “the boundary between controller and controlled,” from the very first pages, and this reflects the link between “just” talking about algorithms and talking about AI. Software is made of algorithms, and AI is made of software, so there we go.

In just over 200 pages and seven chapters simply titled Power, Data, Justice, Medicine, Cars, Crime, and Art, this author organizes primary areas of concern for the question of “Are we in control?” and provides examples in each area.

Power. I felt disappointed when I saw this chapter starts with Deep Blue beating world chess champion Garry Kasparov in 1997 — but my spirits soon lifted as I saw how she framed this example as the way we perceive a computer system affects how we interact with it (shades of Sherry Turkle and Reeves & Nass). She discusses machine learning and image recognition here, briefly. She talks about people trusting GPS map directions and search engines. She explains a 2012 ACLU lawsuit involving Medicaid assistance, bad code, and unwarranted trust in code. Intuition tells us when something seems “off,” and that’s a critical difference between us and the machines.

Algorithms “are what makes computer science an actual science.”

—Hannah Fry, p. 8

Data. Sensibly, this chapter begins with Facebook and the devil’s bargain most of us have made in giving away our personal information. Fry talks about the first customer loyalty cards at supermarkets. The pregnant teenager/Target story is told. In explaining how data brokers operate, Fry describes how companies buy access to you via your interests and your past behaviors (not only online). She summarizes a 2017 DEFCON presentation that showed how supposedly anonymous browsing data is easily converted into real names, and the dastardly Cambridge Analytica exploit. I especially liked how she explains how small the effects of newsfeed manipulation are likely to be (based on research) and then adds — a small margin might be enough to win an election. This chapter wraps up with China’s citizen rating system (Black Mirror in reality) and the toothlessness of GDPR.

Justice. First up is inequality in sentences for crimes, using two U.K. examples. Fry then surveys studies where multiple judges ruled on the same hypothetical cases and inconsistencies abounded. Then the issues with sentencing guidelines (why judges need to be able to exercise discretion). So we arrive at calculating the probability that a person will “re-offend”: the risk assessment. Fry includes a nice, simple decision-tree graphic here. She neatly explains the idea of combining multiple decision trees into an ensemble, used to average the results of all the trees (the random forest algorithm is one example). More examples from research; the COMPAS product and the 2016 ProPublica investigation. This leads to a really nice discussion of bias (pp. 65–71 in the U.S. paperback edition).

Medicine. Although image recognition was mentioned very briefly earlier, here Fry gets more deeply into the topic, starting off with the idea of pattern recognition — and what pattern, exactly, is being recognized? Classifying and detecting anomalies in biopsy slides doesn’t have perfect results when humans do it, so this is one of the promising frontiers for machine learning. Fry describes neural networks here. She gets into specifics about a system trained to detect breast cancer. But image recognition is not necessarily the killer app for medical diagnosis. Fry describes a study of 678 nuns (which previously I’d never heard about) in which it was learned that essays the nuns had written before taking vows could be used to predict which nuns would have dementia later in life. The idea is that an analysis of more data about women (not only their mammograms) could be a better predictor of malignancy.

“Even when our detailed medical histories are stored in a single place (which they often aren’t), the data itself can take so many forms that it’s virtually impossible to connect … in a way that’s useful to an algorithm.”

—Hannah Fry, p. 103

The Medicine chapter also mentions IBM Watson; challenges with labeling data; diabetic retinopathy; lack of coordination among hospitals, doctor’s offices, etc., that lead to missed clues; privacy of medical records. Fry zeroes in on DNA data in particular, noting that all those “find your ancestors” companies now have a goldmine of data to work with. Fry ends with a caution about profit — whatever medical systems might be developed in the future, there will always be people who stand to gain and others who will lose.

Cars. I’m a little burnt out of the topic of self-driving cars, having already read a lot about them. I liked that Fry starts with DARPA and the U.S. military’s longstanding interest in autonomous vehicles. I can’t agree with her that “the future of transportation is driverless” (p. 115). After discussing LiDAR and the flaws of GPS and conflicting signals from different systems in one car, Fry takes a moment to explain Bayes’ theorem, saying it “offers a systematic way to update your belief in a hypothesis on the basis of evidence,” and giving a nice real-world example of probabilistic inference. And of course, the trolley problem. She brings up something I don’t recall seeing before: Humans are going to prank autonomous vehicles. That opens a whole ‘nother box of trouble. Her anecdote under the heading “The company baby” leads to a warning: Always flying on autopilot can have unintended consequences when the time comes to fly manually.

Crime. This chapter begins with a compelling anecdote, followed by a neat historical case from France in the 1820s, and then turns to predictive policing and all its woes. I hadn’t read about the balance between the buffer zone and distance decay in tracking serial criminals, so that was interesting — it’s called the geoprofiling algorithm. I also didn’t know about Jack Maple, a New York City police officer, and his “Charts of the Future” depicting stations of the city’s subway system, which evolved into a data tool named CompStat. I enjoyed learning what burglaries and earthquakes have in common. And then — PredPol. There have been thousands of articles about this since its debut in 2011, as Fry points out. Her summary of the issues related to how police use predictive policing data is quite good, compact and clear. PredPol is one specific product, and not the only one. It is, Fry says, “a proprietary algorithm, so the code isn’t available to the public and no one knows exactly how it works” (p. 157).

“The [PredPol] algorithm can’t actually tell the future. … It can only predict the risk of future events, not the events themselves — and that’s a subtle but important difference.”

—Hannah Fry, p. 153

Face recognition is covered in the Crime chapter, which makes perfect sense. Fry offers a case where a white man was arrested based on incorrect identification of him from CCTV footage at a bank robbery. The consequences of being the person arrested by police can be injury or death, as we all know — not to mention the legal expenses as you try to clear your name after the erroneous arrest. Even though accuracy rates are rising, the chances that you will match a face that isn’t yours remains worrying.

“How do you decide on that trade-off between privacy and protection, fairness and safety?”

—Hannah Fry, p. 172

Art. Here we have “a famous experiment” I’d never heard of — Music Lab, where thousands of music fans logged into a music player app, listened to songs, rated them, and chose what to download (back when we downloaded music). The results showed that for all but the very best and very worst songs, the ratings by other people had a huge influence on what was downloaded in different segments of the app. A song that became a massive hit in one “world” was dead and buried in another. This leads us to recommendation engines such as those used by Netflix and Amazon. Predicting how well movies would do at the box office, turned out to be badly unreliable. The trouble is the lack of an objective measure of quality — it’s not “This is cancer/This is not cancer.” Beauty in the eye of the beholder and all that. A recommendation engine is different because it’s not using a quality score — it’s matching similarity. You liked these 10 movies; I like eight of those; chances are I might like the other two.

Fry goes on to discuss programs that create original (or seemingly original) works of art. A system may produce a new musical or visual composition, but it doesn’t come from any emotional basis. It doesn’t indicate a desire to communicate with others, to touch them in any way.

In her Conclusion, Fry returns to the questions about bias, fairness, mistaken identity, privacy — and the idea of the control we give up when we trust the algorithms. People aren’t perfect, and neither are algorithms. Taking the human consequences of machine errors into account at every stage is a step toward accountability. Building in the capability to backtrack and explain decisions, predictions, outputs, is a step toward transparency.

For details about categories of algorithms based on tasks they perform (prioritization, classification, association, filtering; rule-based vs. machine learning), see the Power chapter (pp. 8–13 in the U.S. paperback edition).

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Symbolic AI: Good old-fashioned AI

The distinction between symbolic (explicit, rule-based) artificial intelligence and subsymbolic (e.g. neural networks that learn) artificial intelligence was somewhat challenging to convey to non–computer science students. At first I wasn’t sure how much we needed to dwell on it, but as the semester went on and we got deeper into the differences among types of neural networks, it was very useful to keep reminding the students that many of the things neural nets are doing today would simply be impossible with symbolic AI.

The difficulty lies in the shallow math/science background of many communications students. They might have studied logic problems/puzzles, but their memory of how those problems work might be very dim. Most of my students have not learned anything about computer programming, so they don’t come to me with an understanding of how instructions are written in a program.

This post by Ben Dickson at his TechTalks blog offers a very nice summary of symbolic AI, which is sometimes referred to as good old-fashioned AI (or GOFAI, pronounced GO-fie). This is the AI from the early years of AI, and early attempts to explore subsymbolic AI were ridiculed by the stalwart champions of the old school.

The requirements of symbolic AI are that someone — or several someones — needs to be able to specify all the rules necessary to solve the problem. This isn’t always possible, and even when it is, the result might be too verbose to be practical. As many people have said, things that are easy for humans are hard for computers — like recognizing an oddly shaped chair as a chair, or distinguishing a large upholstered chair from a small couch. Things we do almost without thinking are very hard to encode into rules a computer can follow.

“Symbolic artificial intelligence is very convenient for settings where the rules are very clear cut, and you can easily obtain input and transform it into symbols.”

—Ben Dickson

Subsymbolic AI does not use symbols, or rules that need symbols. It stems from attempts to write software operations that mimic the human brain. Not copy the way the brain works — we still don’t know enough about how the brain works to do that. Mimic is the word usually used because a subsymbolic AI system is going to take in data and form connections on its own, and that’s what our brains do as we live and grow and have experiences.

Dickson uses an image-recognition example: How would you program specific rules to tell a symbolic system to recognize a cat in a photo? You can’t write rules like “Has four legs,” or “Has pointy ears,” because it’s a photo. Your rules would need to be about pixels and edges and clusters of contrasting shades. Your rules would also need to account for infinite variations in photos of cats.

“You can’t define rules for the messy data that exists in the real world.”

—Ben Dickson

Thus “messy” problems such as image recognition are ideally handled by neural networks — subsymbolic AI.

Problems that can be drawn as a flow chart, with every variable accounted for, are well suited to symbolic AI. But scale is always an issue. Dickson mentions expert systems, a classic application of symbolic AI, and notes that “they require a huge amount of effort by domain experts and software engineers and only work in very narrow use cases.” On top of that, the knowledge base is likely to require continual updating.

An early, much-praised expert system (called MYCIN) was designed to help doctors determine treatment for patients with blood diseases. In spite of years of investment, it remained a research project — an experimental system. It was not sold to hospitals or clinics. It was not used in day-to-day practice by any doctors diagnosing patients in a clinical setting.

“I have never done a calculation of the number of man-years of labor that went into the project, so I can’t tell you for sure how much time was involved … it is such a major chore to build up a real-world expert system.”

—Edward H. Shortliffe, principal developer of the MYCIN expert system (source)

Even though expert systems are impractical for the most part, there are other useful applications for symbolic AI. Dickson mentions “efforts to combine neural networks and symbolic AI” near the end of his post. He points out that symbolic systems are not “opaque” the way neural nets are — you can backtrack through a decision or prediction and see how it was made.

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The trouble with large language models

Yesterday I summarized the first two articles in a series about algorithms and AI by Hayden Field, a technology journalist at Morning Brew. Today I’ll finish out the series.

The third article, This Powerful AI Technique Led to Clashes at Google and Fierce Debate in Tech. Here’s Why, explores the basis of the volatile situation around the firing of Timnit Gebru and later Margaret Mitchell from Google’s Ethical AI unit earlier this year. Both women are highly respected and experienced AI researchers. Mitchell founded the team in 2017.

Central to the situation is a criticism of large language models and a March 2021 paper (On the Dangers of Stochastic Parrots: Can Language Models Be Too Big?) co-authored by Gebru, Mitchell, and two researchers at the University of Washington. The biggest current example is GPT-3, previously covered in several posts here.

“Models this big require an unthinkable amount of data; the entirety of English-language Wikipedia makes up just 0.6% of GPT-3’s training data.”

—”This Powerful AI Technique Led to Clashes at Google and Fierce Debate in Tech. Here’s Why”

The Morning Brew article sums up the very recent and very big improvements in large language models that have come about thanks to new algorithms and faster computer hardware (GPUs running in parallel). It highlights BERT, “the model that now underpins Google Search,” which came out of the research that resulted in the first Transformer. A good at-the-time article about GPT-3’s release was published in July 2020 in MIT’s Technology Review: “OpenAI first described GPT-3 in a research paper published in May [2020].”

One point being — Google fired Timnit Gebru very soon after news and discussion of large language models (GPT-3 especially, but remember Google’s investment in BERT too) ramped up — way up. Her criticism of a previously obscure AI technology (not obscure among NLP researchers, but in the wider world) might have been seen as increasingly inconvenient for Google. Morning Brew summarizes the criticism (not attributed to Gebru): “Because large language models often scrape data from most of the internet, racism, sexism, homophobia, and other toxic content inevitably filter in.”

“Once the barrier to create AI tools and generate text is lower, people could just use it to create misinformation at scale, and having that data coupled with certain other platforms can just be a very disastrous situation.”

—Sandhini Agarwal, AI policy researcher, OpenAi

The Morning Brew article goes well beyond Google’s dismissal of Gebru and Mitchell, bringing in a lot of clear, easy-to-understand explanation of what large language models require (for example, significant energy resources), what they’re being used for, and even the English-centric nature of such models — lacking a gigantic corpus of digitized text in a given human language, you can’t create a large model in that language.

The turmoil in Google’s Ethical AI unit is covered in more detail in this May 2021 article, also by Hayden Field.

It’s easy to find articles that discuss “scary things GPT-3 can do and does” and especially the bias issues; it’s much harder to find information about some of the other aspects covered here. It’s also not just about GPT-3. I appreciated insights from an interview with Emily M. Bender, first author on the “Stochastic Parrots” article. I also liked the explicit statement that many useful NLP tasks can be done well without a large language model. In smaller datasets, finding and accounting for toxic content can be more manageable.

“Do we need this at all? What’s the actual value proposition of the technology? … Who is paying the environmental price for us doing this, and is this fair?”

—Emily M. Bender, professor and director, Professional MS in Computational Linguistics, University of Washington

Finally, in a recap of Morning Brew’s “Demystifying Algorithms” event, editor Dan McCarthy summarized two AI researchers’ answers to one of my favorite questions: What can an algorithm actually know?

An AI system’s ability to generalize — to transfer learning from one domain to another — is still a wide-open frontier, according to Mark Riedl, a computer science professor at Georgia Tech. This is something I remind my students of over and over — what’s called “general intelligence” is still a long way off for artificial intelligence. Riedl works on aspects of storytelling to test whether an AI system is able to “make something new” out of what it has ingested.

Saška Mojsilović, head of Trusted AI Foundations at IBM Research, made a similar point — and also emphasized that “narrow AI” (which is all the AI we’ve ever had, up to now and for the foreseeable future) is not nothing.

She suggested: “We may want to take a pause from obsessing over artificial general intelligence and maybe think about how we create AI solutions for these kinds of problems” — for example, narrow domains such as drug discovery (e.g. new antibiotics) and creation of new molecules. These are extraordinary accomplishments within the capabilities of today’s AI.

This is a half-hour conversation with those two experts:

Thanks to the video, I learned about the Lovelace 2.0 Test, which Riedl developed in 2014. It’s an alternative to the Turing Test.

Mojsilović talked about the perceptions that arise when we use the word intelligence when talking about machines. “The reality is that many things that we call AI today are the same old models that we used to call data science maybe five or six years ago,” she said (at 21:55). She also talked about the need for collaboration between AI researchers and experts in entirely separate fields: “Because we can’t create solutions for the problems that we don’t understand” (at 29:24).

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Summary of the challenges facing algorithms, AI

Hayden Field, a technology journalist at Morning Brew, published a series of articles about algorithms and AI earlier this year, and they’ve been on my TBR list.

First up was Nine Experts on the Single Biggest Obstacle Facing AI and Algorithms in the Next Five Years. Experts: Drago Anguelov (Waymo); Kathy Baxter (Salesforce); David Cox (IBM Watson); Natasha Crampton (Microsoft); Mark Diaz (Ethical AI at Google); Charles Isbell (professor and dean, College of Computing, Georgia Institute of Technology); Peter Lofgren (Stripe); Andrew Ng (co-founder and former head, Google Brain); Cathy O’Neil (author, Weapons of Math Destruction).

Predictably, ethics was noted as a big challenge — O’Neil asked what we will do about unfairness in decisions made by algorithms. Diaz pointed to the need for involving “experts from a wide range of disciplines, including non-technical disciplines,” in the development process, long before an end product emerges. This intersects with ethics and fairness, as the absence of experts and stakeholders opens the door wide to omissions and errors. Baxter was explicit about systemic racism that is embedded in both training data and models. She listed “medical care decisions, hiring recommendations, access to housing and social programs, visa application approvals, school exam results, hate speech detection, dynamic pricing algorithms for ride hailing services, and even dating apps” — as well as face recognition and predictive policing.

“In essence, problems that are not purely technical require solutions that are not purely technical.”

—Mark Diaz, Ethical AI at Google

Isbell spoke of systematic solutions that can be widely applied. “We cannot treat minority groups as exceptions and edge cases,” he said. Cox highlighted transparency and explainability, as well as ethics and bias. He also alluded to adversarial attacks as well as the non-adversarial errors that surprise researchers (possibly due to overfitting). He grouped all this under trust. Crampton also focused on fairness and referred to diversity in teams, similar to Diaz’s and Isbell’s concerns.

Anguelov explained the need for reliable simulations so that systems can scale up to real-world use. He’s talking about the Long Tail problem: the real world throws up too many unexpected situations. Simulations allow testing in ways that don’t risk human lives (think self-driving cars). Lofgren also talked about scale, but in terms of personalization — his example is detecting credit card fraud in real-time based on Big Data that detects abusing IP addresses and then drills down to the individual cards being used. Ng talked about the difficulty in making dependable commercial AI products — basically off-the-shelf solutions.

“We will often need to make hard decisions based on competing priorities, including decisions to not build or deploy a system for certain purposes.”

—Natasha Crampton, Microsoft

Second in the series is titled Amex’s Fraud Detection AI Was Ready to Go Live. Then Covid Hit. This article starts with the idea that large AI models in the field will still need adjustments as unforeseen problems crop up. This echos the concerns about scale raised by Anguelov and Lofgren in the first article in the series.

The challenge thrown by COVID-19 was that all existing models had been developed and adjusted in a non-pandemic world. Then the world changed.

Amex’s fraud-detecting systems are a blend of old-school rule-based systems and newer machine learning techniques. A team of about 30 decision scientists monitors the system round-the-clock and updates it when necessary, at least once a year. The pandemic came at a bad time for Amex, just as they were rolling out a new model.

“Since each generation of a gradient-boosting ML model is typically developed on data from earlier that same year, many of the model’s assumptions no longer made sense” in 2020.

—”Amex’s Fraud Detection AI Was Ready to Go Live. Then Covid Hit”

This is a really interesting article — although I’d read others about issues caused for AI models by pandemic changes, most of those had to do with either healthcare or travel.

Because of increased online traffic in 2020 — more people online, every day, as the pandemic drove work-from-home and stay-at-home schooling — demands on Amazon Web Services (providing servers and processing power to millions of commercial clients such as Amex) grew enormously. This “dwindling cloud capacity” meant testing new solutions for Amex’s model took much longer than usual. The team had to run new simulations that took our new way of life into account, and those simulations required lots of processor juice.

In the end, Amex’s rollout was successful — but it came months later than originally planned. This was a really neat case study and could be discussed in a lot of different contexts.

I’m going to look at the other articles in the series in tomorrow’s post.

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Attention, in machine learning and NLP

Let’s begin at the beginning, with Attention Is All You Need (Vaswani et al., 2017). This is a conference paper with eight authors, six of whom then worked at Google. They contended that neither recurrent neural networks nor convolutional neural networks are necessary for machine translation of languages, and hence the Transformer, “a new simple network architecture,” was born. (Note: It relies on feed-forward neural networks.)

Transformers are the basis for machine translation and other tasks relying on language models. GPT-3 has recently become infamous; others include BERT (from Google) and ELMo.

Before the work by Vaswani and his co-equal co-authors, progress in NLP was limited (although it had advanced a lot since 2012) because of the ways in which RNN models depend on the sequence and position of words in a text. Transformers eliminate those limitations. With recurrent neural networks, there are impediments to parallel processing. Other researchers had previously cracked that nut using ConvNets, but then other limitations were inherent (exponential increase in the number of computational operations). Transformers also eliminate those limitations.

So the Transformer was a first in NLP, a breakthrough. For machine translation, the paper claimed “a new state of the art” (p. 10).

I had learned that an encoder and a decoder connected by an attention module is a standard architecture for machine language translation, e.g. Google Translate. This was true before 2017, so what is the difference effected by the Transformer? It eliminates RNNs and ConvNets from the architecture, yes (“our model contains no recurrence and no convolution”) — but what else?

Attention used in a new way

An attention function can be described as mapping a query and a set of key-value pairs to an output, where the query, keys, values, and output are all vectors. The output is computed as a weighted sum of the values, where the weight assigned to each value is computed by a compatibility function of the query with the corresponding key”(Vaswani et al., 2017, p. 3). I’m okay with that, although I doubt I would be able to explain it to my non–computer science students. (I do explain weights and features when I introduce neural nets to them, and I explain word vectors when we start NLP. The trouble is they don’t know how to write a program, and they certainly don’t understand what a function is.)

There are different attention functions that could be used. One is additive attention; another is dot-product attention, which is multiplicative rather than additive. Dot-product is “much faster and more space-efficient in practice.” Vaswani et al. used a scaled dot-product attention function (p. 4). They also used multi-head attention, meaning the model uses eight parallel attention layers, or heads. The explanation was a bit beyond me, but the gist is that the model can look at multiple things at the same time, like juggling more balls simultaneously.

Multi-head attention — plus the freedom of no-sequence, no-position — enables the Transformer to look at all the context for a word, and do it for multiple words at the same time.

With my rudimentary understanding of recurrent neural nets, I have a fuzzy idea of how this use of attention functions produces better results, mainly by being able to take in and compare more of the text, a little closer to the way human brains hold an entire conversation even though it’s not a literal “recording” of the exact conversation. The way we comprehend meaning when we read has to do with millions of associations built up over a lifetime, as well as many associations within that present text. We are not processing separate little slices of a sentence — our brains handle a text more holistically.

A Transformer does use word embeddings to convert the tokens (both inout and output) to vectors (Vaswani et al., 2017, p. 5). It uses softmax but no LSTMs (because, again, “no recurrence”).

Please help me, YouTube

I found a video (13:04) that helped me in my struggle to understand the Transformer architecture:

It was still a tough climb for me, but this video was particularly helpful with how multi-head attention improves the process. (Obviously the speed improvement is huge.)

Another helpful video (5:33) does a nice job summing up the sequence-based limitations of RNNs: “In general it’s easier for [RNNs] to capture relationships between points that are close to each other than it is to capture relationships between points that are very far from each other — say, several thousand points in the sequence.” In the paper, this is called “path length between long-range dependencies in the network” (Vaswani et al., 2017, p. 6) and identified as one of three motivations for developing the self-attention layers in Transformer.

In fact this second video is much better than the one above, but I liked that one when I watched it first, and maybe (haha!!) the order in which I watched them had an effect. The diagrams for self-attention in this shorter video are very good!

Back to Vaswani et al.

Speaking of self-attention — it was interesting that the authors thought it “could yield more interpretable models.” As in any hidden layer in any neural network, features are determined and weights set by the system itself, not by the human programmers. This is the “learning” in machine learning. The authors noted that the “individual attention heads clearly learn to perform different tasks,” and that many of them “appear to exhibit behavior related to the syntactic and semantic structure of the sentences” (p. 7; my italics).

Cool.

The results section of the paper describes performance using BLEU scores on two different NLP tasks (WMT 2014 English-to-German translation; WMT 2014 English-to-French translation) — reported as best-ever at that time — as well as record-breaking lower training costs, which means time to train the model factored by processor power used (number of GPUs, estimate of the number of floating-point operations).

The successor to the code on which this seminal paper was based is Trax, available on GitHub.

At the end of the paper (pages 13–15) there are math-free visualizations that illustrate what the attention mechanism does. These are well worth a look.

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How to educate the public about AI

Two new items related to educating the general public about artificial intelligence:

The A–Z guide comes from the Oxford Internet Institute and Google. It’s slick, pretty, and animated. It consists of exactly 26 short items, one for each letter of the alphabet: artificial intelligence, bias, climate, datasets, ethics, fakes, etc. The aim is to provide answers in a not-overwhelming way.

I love the idea, but I’m not in love with the execution. For example, the neural networks piece tells us that neural nets “attempt to mimic the structure of the brain,” but they “cannot ‘think’ like humans.” That’s great — clear and accurate. We could quibble about “attempt to mimic the structure,” but we can also let that slide. But then:

“AI design teams can assign each piece of a network to recognizing one of many characteristics. The sections of the network then work as one to build an understanding of the relationships and correlations between those elements — working out how they typically fit together and influence each other.”

To me, that seems misleading. It sounds as if the layers of the neural net are directed by specifically programmed instructions, but all my reading has indicated that the layers determine on their own which features they are detecting. (I’m thinking specifically about image recognition and supervised learning here.) This is important because it contributes to the “black box” problem of machine learning systems.

I also dislike phrases such as “build an understanding,” because that implies more intentionality than these networks actually have.

Giving people short, understandable explanations of specific aspects of AI is a wonderful idea, but the explanations need to be both straightforward and true.

The second education item I linked above comes from MIT’s news office. It describes a “new cross-disciplinary research initiative … to promote the understanding and use of AI across all segments of society.”

“People need to be AI-literate to understand the responsible use of AI and create things with it at individual, community, and societal levels.”

—Cynthia Breazeal, MIT professor, director of Responsible AI for Social Empowerment and Education (RAISE)

This sentiment is becoming more widely voiced as claims for the benefits of AI increase in the media. The idea behind RAISE is good and admirable — yes, people in all walks of life should have some understanding of AI, at least as much as they have an understanding of what makes airplanes fly and what makes computers able to store and retrieve our vacation photos.

Oh, wait.

In the United States, the average person’s understanding of any process involving physics or electronics might not be very good. Many students with stellar high-school grades don’t have a solid grasp of how their laptops or phones work at a basic level. I’m not talking about the students who attend MIT, but I am talking about those who can manage high SAT scores and gain admission to top public universities.

The RAISE initiative has identified four strategic areas for research, education, and outreach:

  • Diversity and inclusion in AI
  • AI literacy in pre-K–12 education
  • AI workforce training
  • AI-supported learning

But let’s go back to the A–Z guide and look at the segment about binary code, Zeros & Ones. It tells us that 0’s and 1’s are “the foundational language of computers.” It tells us that a particular long sequence of 0’s and 1’s means “Hello” to a computer. In one sense, that is true — but it really explains nothing to a layman. A computer system doesn’t know what “Hello” is (or means) any more than a rock does.

To accomplish AI literacy, we need to accomplish computer literacy. We need to teach and explain — clearly and accurately — to students at all levels what computers can and cannot do, how they are programmed, and how AI is different from, say, writing a game program that plays tic-tac-toe as well as any human can. I can write and run a winning tic-tac-toe program on an average laptop if I know which algorithms to use in my code — but there’s nothing remotely like intelligence in that program.

We need to add caveats every time we say something like “the computer learns,” or “the system understands.”

It will be fantastic if RAISE (and other outreach programs) can raise the level of computer literacy among Americans. It’s an important goal in this era of AI hype and euphoric claims, because it will be so much easier for people to be duped, exploited, mistreated, sidelined, marginalized, and/or denied jobs, loans, mortgages, healthcare, or admission to universities if they don’t understand what AI is and how it works.

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Multiple facets of ethics in AI

The Center for Responsible AI at New York University has published a free online course titled “AI Ethics: Global Perspectives.”

The course consists of a series of videos produced by many different people in countries around the world. The instructors include computer science and engineering professors as well as researchers in various fields, including government, health care, and the humanities. These are the lectures I intend to watch:

Lectures still to come:

  • Renee Cummings, a U.S. criminologist and consultant, will discuss “Bias in Data and AI: Myth, Mistrust, and Myopia.”
  • Susan Scott-Parker will discuss “AI Powered Disability Discrimination: How Do You Lip Read a Robot Recruiter?”

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AI in Media and Society by Mindy McAdams is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
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Figuring It Out: Transformers for NLP

It was a challenge for me to figure out how to teach non–computer science students about word vectors. I wanted them to have a clear idea of how words and their meanings are represented for use in an AI system — otherwise, I worried they would assume something like a written dictionary with text and definitions. I also wanted them to know that it wasn’t something simple like “each word has a numerical code assigned to it.” So we spent some time talking about what a vector is and what “n-dimensional space” means.

Slide above by Mindy McAdams (copyright © 2021)
Slide above by Mindy McAdams (copyright © 2021)

Now I need to work out how to teach them about transformers. I found a surprisingly clear article at Orange.com (formerly France Télécom), on their Hello Future website about research and innovation. I’m going to quote a large section from that article:

“Originally, in 2013, word embeddings (such as Word2Vec, Glove, or Fasttext) were able to capture representations of words in the form of vectors taking into account the context of neighboring words in large volumes of text. Two words appearing in similar contexts were ‘embedded’ into N-dimensional space, to neighboring points in this space. This approach has led to significant advances in the field of NLP, but also has its limitations. From 2018 a new way of generating these word vectors emerged. Rather than selecting the vector of a word in a previously learnt static ‘dictionary,‘ a model is responsible for dynamically generating the vector representation of a word. A word is thus projected to a vector not only according to its prior meaning, but also according to the context in which it appears. The models for effective realization of these contextual projections (BERT, ELMO and derivatives, GPT and its successors) are based on a simple yet powerful architecture called Transformer.” (Spelling and punctuation edited for American English.)

I know that paragraph might not make sense if you haven’t already learned about word vectors. The key is that transformers are able to build on and enhance the machine accuracy of what a word or sentence means by taking into account its context in the current data. So you do have a language model, previously trained on a large corpus, but the transformer analyzes the present text input in a more holistic way, transforming the vectors as it goes.

Again quoting from the Orange.com article: “While previous approaches … could model contextual dependencies, they were always constrained by referencing words by their positions [in the sentence]. Attention is about referencing by content. Instead of looking for relationships with other words in the context at given positions, attention allows you to search for relationships with all words in the context, and through a very effective implementation, it allows you to rely on the most similar words to improve prediction, whatever their position in context.”

The role of the attention module is explained in a 2017 paper that, according to Google Scholar, has been cited more than 20,000 times: Attention Is All You Need. See the PDF for diagrams of the Transformer network architecture.

Language models produced by transformers include BERT (developed by Google, and which powers Google searches), ELMo, and GPT-3. These so-called large language models have raised many concerns, particularly around ethics, as their interior processes are a black box, and their immense training data has included biased and toxic texts. The Orange.com article includes two charts that illustrate differences among BERT, ELMo, and three generations of GPT.

An important aspect of transformers is that they produce these large language models from unlabeled data, and when developing applications based on transformers and such models, good results can be obtained with only a small amount of additional training data (“few-shot learning”).

Orange — like many other companies — is using large language models for classification and information-extraction tasks such as: “sentiment analysis, personal data detection, detection and identification of named entities, syntactic dependency analysis, semantic parsing, co-reference resolution,” and question answering. These tasks involve customer-service applications as well as internal data analysis.

Much of this post is based on the article The GPT-3 language model, revolution or evolution? (February 2021).

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AI in Media and Society by Mindy McAdams is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
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