Seymour Papert’s Mindstorms was published by Basic Books in 1980, and outlines his vision of children using computers as instruments for learning. A second edition, with new Forewords by John Sculley and Carol Sperry, was published in 1993. The book remains as relevant now as when first published almost forty years ago.
The Media Lab is grateful to Seymour Papert’s family for allowing us to post the text here. We invite you to add your comments and reflections.
If you are interested in purchasing the print edition of Mindstorms, please visit Basic Books.
This short introduction to category theory is for readers with relatively little mathematical background. At its heart is the concept of a universal property, important throughout mathematics. After a chapter introducing the basic definitions, separate chapters present three ways of expressing universal properties: via adjoint functors, representable functors, and limits. A final chapter ties the three together.
For each new categorical concept, a generous supply of examples is provided, taken from different parts of mathematics. At points where the leap in abstraction is particularly great (such as the Yoneda lemma), the reader will find careful and extensive explanations.
My friend Tom Leinster has written a great introduction to that wonderful branch of math called category theory! It’s free:
It starts with the basics and it leads up to a trio of related concepts, which are all ways of talking about universal properties.
Huh? What’s a ‘universal property’?
In category theory, we try to describe things by saying what they do, not what they’re made of. The reason is that you can often make things out of different ingredients that still do the same thing! And then, even though they will not be strictly the same, they will be isomorphic: the same in what they do.
A universal property amounts to a precise description of what an object does.
Universal properties show up in three closely connected ways in category theory, and Tom’s book explains these in detail:
through representable functors (which are how you actually hand someone a universal property),
through limits (which are ways of building a new object out of a bunch of old ones),
through adjoint functors (which give ways to ‘freely’ build an object in one category starting from an object in another).
If you want to see this vague wordy mush here transformed into precise, crystalline beauty, read Tom’s book! It’s not easy to learn this stuff – but it’s good for your brain. It literally rewires your neurons.
Here’s what he wrote, over on the category theory mailing list:
My introductory textbook “Basic Category Theory” was published by Cambridge University Press in 2014. By arrangement with them, it’s now also free online:
It’s also freely editable, under a Creative Commons licence. For instance, if you want to teach a class from it but some of the examples aren’t suitable, you can delete them or add your own. Or if you don’t like the notation (and when have two category theorists ever agreed on that?), you can easily change the Latex macros. Just go the arXiv, download, and edit to your heart’s content.
There are lots of good introductions to category theory out there. The particular features of this one are:
• It’s short.
• It doesn’t assume much.
• It sticks to the basics.
T. Leinster, Basic Category Theory, 1st ed. Cambridge University Press, 2014.
I just saw Emily Riehl‘s new book Category Theory in Context on the shelves for the first time. It’s a lovely little volume beautifully made and wonderfully typeset. While she does host a free downloadable copy on her website, the book and the typesetting is just so pretty, I don’t know how one wouldn’t purchase the physical version.
I’ll also point out that this is one of the very first in Dover’s new series Aurora: Dover Modern Math Originals. Dover has one of the greatest reprint collections of math texts out there, I wish them the best in publishing new works with the same quality and great prices as they always have! We need more publishers like this.
Peter Woit has just made the final draft (dated 10/25/16) of his new textbook Quantum Theory, Groups and Representations: An Introduction freely available for download from his website. It covers quantum theory with a heavy emphasis on groups and representation theory and “contains significant amounts of material not well-explained elsewhere.” He expects to finish up the diagrams and publish it next year some time, potentially through Springer.
Advanced Data Analysis from an Elementary Point of View
by Cosma Rohilla Shalizi
This is a draft textbook on data analysis methods, intended for a one-semester course for advance undergraduate students who have already taken classes in probability, mathematical statistics, and linear regression. It began as the lecture notes for 36-402 at Carnegie Mellon University.
By making this draft generally available, I am not promising to provide any assistance or even clarification whatsoever. Comments are, however, welcome.
The book is under contract to Cambridge University Press; it should be turned over to the press before the end of 2015. A copy of the next-to-final version will remain freely accessible here permanently.
Generalized Linear Models and Generalized Additive Models
Classification and Regression Trees
II. Distributions and Latent Structure
Relative Distributions and Smooth Tests of Goodness-of-Fit
Principal Components Analysis
Nonlinear Dimensionality Reduction
III. Dependent Data
Spatial and Network Data
IV. Causal Inference
Graphical Causal Models
Identifying Causal Effects
Causal Inference from Experiments
Estimating Causal Effects
Discovering Causal StructureAppendices
Data-Analysis Problem Sets
Reminders from Linear Algebra
Big O and Little o Notation
Algebra with Expectations and Variances
Propagation of Error, and Standard Errors for Derived Quantities
chi-squared and the Likelihood Ratio Test
Proof of the Gauss-Markov Theorem
Rudimentary Graph Theory
Writing R Functions
Random Variable Generation
Unified treatment of information-theoretic topics (relative entropy / Kullback-Leibler divergence, entropy, mutual information and independence, hypothesis-testing interpretations) in an appendix, with references from chapters on density estimation, on EM, and on independence testing
More detailed treatment of calibration and calibration-checking (part II)
Missing data and imputation (part II)
Move d-separation material from “causal models” chapter to graphical models chapter as no specifically causal content (parts II and IV)?
Expand treatment of partial identification for causal inference, including partial identification of effects by looking at all data-compatible DAGs (part IV)
Figure out how to cut at least 50 pages
Make sure notation is consistent throughout: insist that vectors are always matrices, or use more geometric notation?
Move simulation to an appendix
Move variance/weights chapter to right before logistic regression
Move some appendices online (i.e., after references)?
(Text last updated 30 March 2016; this page last updated 6 November 2015)
I ran across a link to this textbook by way of a standing Google alert, and was excited to check it out. I was immediately disappointed to think that I would have to wait another month and change for the physical textbook to be released, but made my pre-order directly. Then with a bit of digging around, I realized that individual chapters are available immediately to quench my thirst until the physical text is printed next month.
UNAM Mexico City has an available free download of Carlos Gershenson’s 2007 text.
Complex systems are usually difficult to design and control. There are several particular methods for coping with complexity, but there is no general approach to build complex systems. In this book I propose a methodology to aid engineers in the design and control of complex systems. This is based on the description of systems as self-organizing. Starting from the agent metaphor, the methodology proposes a conceptual framework and a series of steps to follow to find proper mechanisms that will promote elements to find solutions by actively interacting among themselves.
This is the draft version of a textbook, which aims to introduce the quantum information science viewpoints on condensed matter physics to graduate students in physics (or interested researchers). We keep the writing in a self-consistent way, requiring minimum background in quantum information science. Basic knowledge in undergraduate quantum physics and condensed matter physics is assumed. We start slowly from the basic ideas in quantum information theory, but wish to eventually bring the readers to the frontiers of research in condensed matter physics, including topological phases of matter, tensor networks, and symmetry-protected topological phases.
“The Mathematics Literature Project intends to survey the state of the freely accessible mathematics literature. In particular, it will index freely accessible URLs for mathematics articles. These are legitimately hosted copies of the article (i.e. at publishers, the arXiv, institutional repositories, or authors’ homepages), which are freely available in any browser, anywhere in the world.”
What's wrong with the economics of the textbook industry, and what students, parents, professors, and universities can do to mitigate the ever-rising price of textbooks.
t’s the beginning of yet another quarter/semester (or ovester, if you prefer) and a new crop of inquiries have come up around selling back used textbooks and purchasing new textbooks for upcoming classes. I’m not talking about the philosophical discussion about choosing your own textbooks that I’ve mentioned before. I’m considering, in the digital era,
What are the best options for purchasing, renting, or utilizing textbook products in what is a relatively quickly shifting market?
The popular press has a variety of evergreen stories that hit the wire at the beginning of each semester that scratch just the surface of the broader textbook issue or focus on one tiny upstart company that promises to drastically disrupt the market (yet somehow never does), but these articles never delve just a bit deeper into the market to give a broader array of ideas and, more importantly, solutions for the students/parents who are spending the bulk of the money to support the inequalities the market has built.
I aim to facilitate some of this digging and revealing based on years of personal book buying experience as well as having specified textbooks as an instructor in the past.
Most current students won’t have been born late enough that electronic files for books and texts will have been common enough to prefer them over physical texts, but with practice and time, many will prefer electronic texts in the long term, particularly as one can highlight, mark up, and more easily search, store, and even carry electronic texts.
Before taking a look at the pure economics of the market for the various forms of purchase, resale, or even renting, one should first figure out one’s preference for reading format. There are obviously many different means of learning (visual, auditory, experiential, etc.) which some will prefer over others, so try to tailor your “texts” to your preferred learning style as much as possible. For those who prefer auditory learning modes, be sure to check out alternatives like Audible or the wealth of online video/audio materials that have proliferated in the MOOC revolution. For those who are visual learners or who learn best by reading, do you prefer ebook formats over physical books? There are many studies showing the benefit of one over the other, but some of this comes down to personal preference and how comfortable one is with particular formats. Most current students won’t have been born late enough that electronic files for books and texts will have been common enough to prefer them over physical texts, but with practice and time, many will prefer electronic texts in the long term, particularly as one can highlight, mark up, and more easily search, store, and even carry electronic texts. It’s taken me (an avowed paper native) several years, but I now vastly prefer to have books in electronic format for some of the reasons indicated above in addition to the fact that I can carry a library of 2,500+ books with me almost anywhere I go. I also love being able to almost instantly download anything that I don’t currently own but may need/want.
The one caveat I’ll mention, particularly for visual learners (or those with pseudo-photographic or eidetic memory), is that they attempt to keep a two-page reading format on their e-reading devices as their long-term memory for reading will increase with the ability to place the knowledge on the part of the page(s) where they originally encountered it (that is, I remember seeing that particular item on the top left, or middle right portion of a particular page.) Sometimes this isn’t always possible due to an e-reader’s formatting capabilities or the readability of the size of the text (for example, a .pdf file on a Kindle DX would be preferable to the same file on a much smaller smartphone) , but for many it can be quite helpful. Personally, I can remember where particular words and grammatical constructs appeared in my 10th grade Latin text many years later while I would be very unlikely to be able to do this with the presentation of some modern-day e-readers or alternate technologies like rapid serial visual presentation (RSVP).
Purchasing to Keep
Personally, as a student and a bibliophile (read: bibliomaniac), I would typically purchase all of the physical texts for all of my classes. I know this isn’t a realizable reality for everyone, so, for the rest, I would recommend purchasing all of the texts (physical or electronic, depending on one’s preference for personal use) in one’s main area of study, which one could then keep for the long term and not sell back. This allows one to build a library that will serve as a long term reference for one’s primary area(s) of study.
Renting vs Short-term Ownership
In general, I’m opposed to renting books or purchasing them for a semester or year and then returning them for a partial refund. It’s rarely a great solution for the end consumer who ends up losing the greater value of the textbook. Even books returned and sold later as used, often go for many multiples of their turn in price the following term, so if it’s a newer or recent edition, it’s probably better to hold on to it for a few months and then sell it for a used price, slightly lower than the college bookstore’s going rate.
For tangential texts in classes I know I don’t want to keep for the long term, I’d usually find online versions or borrow (for free) from the local college or public library (many books are available electronically through the library or are borrow-able through the library reserve room.)
Often college students forget that they’re not just stuck with their local institutional library, so I’ll remind everyone to check out their local public library(s) as well as other nearby institutional libraries and inter-library loan options which may give them longer term loan terms.
General Economics in the Textbook Market
One of the most important changes in the textbook market that every buyer should be aware of: last year in Kirtsaeng v. John Wiley & Sons, Inc.the US Supreme Court upheld the ability for US-based students to buy copies of textbooks printed in foreign countries (often at huge cut-rate prices) [see also Ars Technica]. This means that searching online bookstores in India, Indonesia, Pakistan, etc. will often find the EXACT same textbooks (usually with slightly different ISBNs, and slightly cheaper paper) for HUGE discounts in the 60-95% range.
Example: I recently bought an international edition of Walter Rudin’s Principles of Mathematical Analysis (Amazon $121) for $5 (and it even happened to ship from within the US for $3). Not only was this 96% off of the cover price, but it was 78% off of Amazon’s rental price! How amazing is it to spend almost as much to purchase a book as it is to ship it to yourself!? I’ll also note here that the first edition of this book appeared in 1964 and this very popular third edition is from 1976, so it isn’t an example of “edition creep”, but it’s still got a tremendous mark up in relation to other common analysis texts which list on Amazon for $35-50.
For some of the most expensive math/science/engineering texts one can buy an edition one or two earlier than the current one. In these cases, the main text changes very little, if any, and the primary difference is usually additional problems in the homework sections (which causes small discrepancies in page number counts). If necessary, the problem sets can be easily obtained via the reserve room in the library or by briefly borrowing/photocopying problems from classmates who have the current edition. The constant “edition-churning” by publishers is mean to help prop up high textbook prices.
Definition: “Edition Churning” or “Edition Creep“: a common practice of textbook publishers of adding scant new material, if any, to textbooks on a yearly or every-other-yearly basis thereby making older editions seem prematurely obsolete and thereby propping up the prices of their textbooks. Professors who blithely utilize the newest edition of a texbook are often unknowingly complicit in propping up prices in these situations.
One may find some usefulness or convenience in traditional bookstores, particularly Barnes & Noble, the last of the freestanding big box retailers. If you’re a member of their affinity program and get an additional discount for ordering books directly through them, then it may not be a horrible idea to do so. Still, they’re paying for a relatively large overhead and it’s likely that you’ll find cheaper prices elsewhere.
These are becoming increasingly lean and many may begin disappearing over the next decade or so, much the way many traditional bookstores have disappeared in the last decade with the increasing competition online. Because many students aren’t the best at price comparison, however, and because of their position in the economic chain, many are managing to hang on quite well. Keep in mind that many campus bookstores have fine print deals in which they’ll match or beat pricing you find online, so be sure to take advantage of this fact, particularly when shipping from many services will make an equivalent online purchase a few dollars more expensive.
There are fewer and fewer of these around these days and even fewer textbook-specific stores that traditionally sprouted up next to major campuses. This last type may not be a horrible place to shop, but they’re likely to specialize in used texts of only official texts. Otherwise, general used bookstores are more likely to specialize in paperbacks and popular used fiction and have very lean textbook selection, if any.
Naturally when shopping for textbooks there are a veritable wealth of websites to shop around online including: Amazon, Alibris, Barnes & Noble, AbeBooks, Google Play, Half/EBay. Chegg, Valore, CampusBookRentals, TextBooks.com, and ECampus. But in the Web2.0 world, we can now uses websites with even larger volumes of data and meta-data as a clearing-house for our shopping. So instead of shopping and doing price comparison at the dozens of competing sites, why not use a meta-site to do the comparison for us algorithmically and much more quickly.
There are a variety of meta-retailer shopping methods including several browser plugins and comparison sites (Chrome, Firefox, InvisibleHand, PriceBlink, PriceGong, etc.) that one can install to provide pricing comparisons, so that, for example, while shopping on Amazon, one will see lower priced offerings from their competitors. However, possibly the best website I’ve come across for cross-site book comparisons is GetTextbooks.com. One can easily search for textbooks (by author, title, ISBN, etc.) and get back a list of retailers with copies that is sortable by price (including shipping) as well as by new/used and even by rental availability. They even highlight one entry algorithmicly to indicate their recommended “best value”.
Similar to GetTextbooks is the webservice SlugBooks, though it doesn’t appear to search as many sites or present as much data.
When searching for potential textbooks, don’t forget that one can “showroom” the book in one’s local bookstore or even at one’s local library(s). This is particularly useful if one is debating whether or not to take a particular class, or if one is kicking tires to see if it’s really the best book for them, or if they should be looking at other textbooks.
From an economic standpoint, keep in mind there is usually more availability and selection on editions bought a month or so before the start of classes, as often-used texts are used by thousands of students over the world, thus creating a spot market for used texts at semester and quarter starts. Professors often list their textbooks when class listings for future semesters are released, so students surfing for the best deals for used textbooks can very often find them in mid-semester (or mid-quarter) well before the purchasing rush begins for any/most titles.
And finally, there is also the black market (also known as outright theft), which is usually spoken of in back-channels either online or in person. Most mainstream articles which reference this portion of the market usually refer tangentially to a grey market in which one student passes along a .pdf or other pirated file to fellow students rather than individual students being enterprising enough to go out hunting for their own files.
Most will know of or have heard about websites like PirateBay, but there are a variety of lesser-known torrent sites which are typically hosted in foreign countries which extend beyond the reach of the United States Copyright law enforcement. Increasingly, mega-pirate websites in the vein of the now-defunct Library.nu (or previously Gigapedia) or the slowly dying empire of Library Genesis are hiding all over the web and become quick and easy clearing houses for pirated copies of ebooks, typically in .pdf or .djvu formats, though many are in .epub, .mobi, .azw, or alternate e-book formats. The typical set up for these sites is one or more illegal file repositories for allowing downloads with one (or more) primary hubs that don’t necessarily store the pirated materials, but instead serve as a searchable hub which points to the files.
Creative advanced searches for book authors, titles, ISBNs along with the words .pdf, .djvu, torrent, etc. can often reveal portions of this dark web. Naturally, caveat emptor applies heavily to these types of sites as often files can be corrupted or contain viruses to unwary or unwitting thieves. Many of these sites may attempt to extract a small token monthly fee as a subscription or will rely heavily on serving banner advertising to help to offset large web hosting and traffic fees associated with their maintenance, though it is posited that many of them make in the millions of dollars in profit annually due to advertising arrangements, though this is incredibly hard to validate given the nature of these types of markets and how they operate.
Rather than stoop as low as finding textbooks on the black market this way, students should place pressure on their professors, the faculty of their departments, and their colleges or universities to help assist in smoothing out some of the pricing inequities in the system (see below). In the long run, this will not only tend to help them, but many future generations of students who will be left adrift in the market otherwise.
Long Term Solution(s) to Improving the Textbook Market
The biggest primary issue facing the overpriced textbook market is that the end consumers of the textbooks aren’t really firmly in charge of the decision of which textbook to purchase. This is why I advocate that students research and decide by themselves which textbook they’re going to use and whether or not they really need to make that purchase. Instead, individual professors or the departments for which they work are dictating the textbooks that will be purchased. The game theory dynamics behind this small decision are the massive fulcrum which allows the publishing industry to dictate their own terms. Students (and parents) should, in a sense, unionize and make their voices heard not only to the professors, but to the departments and even the colleges/universities which they’re attending. If universities took a strong stance on how the markets worked, either for or against them and their students, they could create strong market-moving forces to drastically decrease the cost of textbooks.
The other larger issue is that market forces aren’t allowed to play out naturally in the college textbook market. Publishers lean on professors and departments to “adopt” overpriced textbooks. These departments in turn “require” these texts and students aren’t questioning enough to use other texts for fear of not succeeding in courses. If the system were questioned, they’d realize that instead of their $200-300 textbook, they could easily purchase alternate, equivalent, and often even better textbooks for $20-50. To put things into perspective, the time, effort, energy, and production cost for the typical book isn’t drastically different than the average textbook, yet we’re not paying $250 for a copy of the average new hardcover on the best seller list. I wouldn’t go so far as to say that universities, departments, and professors are colluding with publishers, but they’re certainly not helping to make the system better.
I’ve always taken the view that the ‘required’ textbook was really just a ‘suggestion’. (Have you ever known a professor to fail a student for not purchasing the ‘required’ textbook?!)
In past generations, one of the first jobs of a student was to select their own textbook. Reverting back to this paradigm may help to drastically change the economics of the situation. For the interested students, I’ve written a bit about the philosophy and mechanics here: On Choosing Your Own Textbooks.
Basic economics 101 theory of supply and demand would typically indicate to us that basic textbooks for subjects like calculus, intro physics, or chemistry that are used by very large numbers of students should be not only numerous, but also very cheap, while more specialized books like Lie Groups and Lie Algebras or Electromagnetic Theory should be less numerous and also more expensive. Unfortunately and remarkably, the most popular calculus textbooks are 2-5 times more expensive than their advanced abstract mathematical brethren and similarly for introductory physics texts versus EM theory books.
To drastically cut down on these market inequities, when possible, Colleges and Universities should:
Heavily discourage “edition creep” or “edition churning” when there really aren’t major changes to textbooks. In an online and connected society, it’s easy enough to add supplemental errata or small amounts of supplemental material by means of the web.
Quit making institution-specific readers and sub-editions of books for a specific department
If they’re going to make departmental level textbook choices, they should shoulder the burden of purchasing all the textbooks in quantity (and taking quantity discounts). I’ll note here, that students shouldn’t encourage institutions to bundle the price of textbooks into their tuition as then there is a “dark curtain,” which allows institutions to take the drastic mark-ups for themselves instead of allowing the publishers to take it or passing it along to their students. Cross-reference Benjamin Ginsberg’s article Administrators Ate My Tuition or his much longer text The Fall of the Faculty (Oxford University Press, 2013).
Discourage the use of unpopularly used textbooks written by their own faculty. Perhaps a market share of 5-10% or more should be required for a common textbook to be usable by a department, and, until that point, the professor should compete aggressively to build market share? This may help encourage professors to write new original texts instead of producing yet-another-introductory-calculus-textbook that no one needs.
Discourage packaged electronic supplemental materials, which
are rarely used by students,
could be supplied online for free as a supplement,
and often double or triple the price of a textbook package.
Strongly encourage professors to supply larger lists of relatively equivalent books and encourage their students to make their purchase choices individually.
Consider barring textbook sales on campus and relying on the larger competitive market to supply textbooks to students.
Calibre: E-book and Document Management Made Simple
As an added bonus, for those with rather large (or rapidly growing) e-book collections, I highly recommend downloading and using the free Calibre Library software. For my 2000+ e-books and documents, this is an indispensable program that is to books as iTunes is to music. I also use it to download dozens of magazines and newspapers on a daily basis for reading on my Kindle. I love that it’s under constant development with weekly updates for improved functionality. It works on all major OSes and is compatible with almost every e-reader on the planet. Additionally, plug-ins and a myriad of settings allow for additional extensibility for integration with other e-book software and web services (for example: integration with GoodReads or the ability to add additional data and meta-data to one’s books.)
Be sure to read through the commentary on some of these posts for some additional great information.
What other textbook purchasing services and advice can you offer the market?
I invite everyone to include their comments and advice below as I’m sure I haven’t covered the topic completely or there are bound to be new players in the space increasing competition as time goes by.