Help proofread free textbooks for South African children August 25, 2010
Posted by David Speyer in blog triumphalism, good journals.3 comments
I don’t know much about this cause, having just learned about it from Tom Leinster today, but it sounds like a good one and it’s important to get the word out fast.
The Free High School Science Texts project aims to compile free (both in the sense of without cost and the sense of unrestricted by copyright) High School science texts. They have a good chance to get their books used in South African schools, providing a major test ground — if they can do a ton of proofreading this week.
If you are the sort of person who always spots typos in the papers you read, and are happy with LaTeX, read this post and this one and, if you have the time, volunteer to do some proofreading.
After all, it’s one week before classes start. I’m sure we’re all looking for ways to procrastinate
Apologies to any babies who were thrown out with the bathwater August 11, 2010
Posted by David Speyer in Uncategorized.7 comments
I just deleted more than 1000 spam messages from our filter, at last half of them on Noah’s recent post about bad editing. My apologies if any real comments got caught in the mix.
The Brauer Groupoid August 11, 2010
Posted by Noah Snyder in fusion categories, groupoids, Number theory, quantum algebra.3 comments
Recall that the Brauer group of a field k consists of central simple algebras over k up to Morita equivalence with the group operation given by tensor product. For example, the Brauer group of the real numbers is Z/2 because the only central simple algebras are matrix algebras over 
What I’d like to explain in this post is a follow-your-nose proof of this isomorphism which comes from thinking about fusion categories. Namely, attached to any fusion category there is a very natural object called Brauer-Picard groupoid (introduced by Etingof-Nikshych-Ostrik). For the special case of the fusion category of vector spaces over k the Brauer-Picard groupoid has a point for every seperable extension of k and the group of automorphisms of the point k gives exactly the Brauer group. However, one can also look at the group of automorphisms of other points, in particular the point 
This example came up in work in progress with Pinhas Grossman where we compute the Brauer-Picard groupoid of the fusion categories which come from the Haagerup subfactor. As we’ll see the automorphism group of a point in the Brauer-Picard groupoid has a subgroup consisting of certain “outer automorphisms.” I wanted to have a good example in hand where the outer automorphism group of different points were different in order to test certain lemmas. The example in this post is as extreme as things can get, for
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Value removed by journals August 10, 2010
Posted by Noah Snyder in evil journals.42 comments
It is a truth universally acknowledged that journals fail to add significant value in a way that justifies their high prices (we write, typeset, referee, edit, and they do basically nothing except charge an arm and a leg for it). However, I think it is underappreciated the ways in which some journals actually take away value. Typically by wasting our time with bad interfaces or imposing unreasonable typesetting/file format requirements. I’m in the middle of a particularly hellacious experience with the Journal of Functional Analysis (whose support staff have been unhelpful on top of incompetent) but I’ve also run into similar inconveniences with IMRN (where at least the support staff was helpful in getting around the problems).
Suppose we lived in a world where journals did the following
- Took submissions of papers by receiving their arXiv ID number.
- Refereed them and had the authors make necessary changes.
- Slapped the journal’s logo on the paper and called it accepted.
That to me is the baseline of how things should work (and is roughly how things do work at many journals: ANT/G&T/AGT obviously, but also CMP/JAMS/Acta were more or less similar). Anything else the journals do beyond that should add value rather than remove it. Here are ways that journals often remove value:
- Requiring additional typsetting work prior to submission. I’m happy to do a little bit of grunt work on an accepted paper, but it’s very frustrating to struggle to just submit a paper. ArXiv or PDF should be good enough for submission.
- Having difficult to use and poorly engineered submission systems. (E.g. JFA has no way of allowing you to delete multiple files you’ve uploaded. So if you upload 200 images and then need to change them because their system failed to compile you need to remove each file manually.)
- Having unnecessarily strict file format requirements (e.g. JFA doesn’t want .png, and IMRN wasn’t able to deal with TikZ).
- Having strange limitations on how files can be uploaded, in particular not allowing subfolders (JFA and IMRN) or only allowing particular sorts of zip formats (IMRN).
- Inserting the evil “et al.” into citations.
- Update: Introducing mathematical errors during copy-editing
Any other important ways that journals remove value that I’m missing?
UPDATE This post has been attracting an extraordinary amount of spam. (See post above.) I (DES) have changed the title to see if that helps.
Creative grading schemes August 6, 2010
Posted by Noah Snyder in Uncategorized.19 comments
This fall I’ll be teaching my first regular college class (I’d only taught sections at Berkeley, though I suppose the summer sophomore tutorial I taught at Harvard might count). It’s on group representation theory, which is my favorite subject, so I’m excited about it. I was just thinking about some possible homework problems, and I got to thinking about creative and unusual grading schemes I’ve seen in previous classes I’d taken, and figured that might make a fun blog discussion topic. (Since this is my first time teaching I won’t be experimenting with any unusual grading this time around, though I think it might be interesting to try one of these in the future.)
Redos:
At the Ross summer math program if you don’t answer a problem satisfactorily then you get a REDO. This means you’re expected to go back and redo the problem and get it right. I’ve never seen this tried in a regular class, but I think it could be a good idea for an “intro to proof writing” class. The point being that in such a class the material itself isn’t super important, and so if you do fewer homework problems total but learn how to do them right that’s a good tradeoff.
Grading out of many points:
When I took group representation theory from Richard Taylor, the exams were graded out of a ridiculous number of points. A 5 question midterm would be out of 600 or so points. At first glance this seems silly (and it certainly would be a bad idea for a class with multiple graders where you want consistency between graders), but it actually works very well. Here’s the point: if someone does something you don’t like no matter how small it is you can take off points! Unclear sentence? Minus 1. Used the wrong terminology? Minus 3 points. This way the grader can effectively communicate relatively small shortcomings in your write-ups, which wouldn’t be possible if you were grading out of a smaller number of points.
Perfection bonus
This idea comes from a class that I didn’t take our first year of grad school with Givental, so perhaps someone who took the class can correct me on the details. The basic idea that was for the final in addition to points for each problem you got, there was a pool of extra points which you got if you never wrote anything false on the exam. But as soon as you wrote something that was wrong you lost those points. This is good training for graduate students who soon won’t have graders telling them when they made a mistake, and it’s a good way to keep people from spewing nonsense in an attempt to get partial credit. If I remember correctly the perfection bonus was quite substantial (I want to say it was worth as much as a full question on an exam where you need a little more than 2 correct solutions.)
What do people think of these ideas? Any other interesting grading schemes you’ve heard of?
