Making an Accessible Open Logic Textbook (for Dyslexics)

In the design and layout of the Open Logic Project texts as well as the Calgary Remix of the intro text forall x, we’ve tried to follow the recommendations of the BC Open Textbook Accessibility Toolkit already. Content is organized into sections, important concepts are highlighted (e.g., colored boxes around definitions and theorems), chapters have summaries, etc. We picked an easily readable typeface and set line and page lengths to enhance readability according to best (text)book design practices and research. We’ve started experimenting specifically with a version of forall x that is better for dyslexic readers (see issue 22). Readability for dyslexics is affected by typeface, type size, letter and line spacing. Charles Bigelow gives a good overview of the literature here. Some typefaces are better for dyslexic readers than others. Generally, sans-serif fonts are preferable, but individual letter design is also relevant. The British Dyslexia Association has a page on it: the design of letters should make it easy to distinguish letters, not just when they are close in shape (e.g., numeral 1, uppercase I and lowercase l; numeral 0, uppercase O and lowercase o, lowercase a) but also when they are upside-down or mirror images (e.g., p and q, b and d; M and W). In one study of reading times and reported preference, sans-serif fonts Arial, Helvetica, and Verdana ranked better than other fonts such as Myriad, Courier, Times, and Garamond, and even the specially designed Open Dyslexic typeface. Although it would be possible to get LaTeX to output in any available typefaces, it’s perhaps easiest to stick to those that come in the standard LaTeX distributions. The typeface that strikes me as best from the readability perspective seems to me to be Go Sans. It was designed by Bigelow & Holmes with readability in mind and does distinguish nicely between p and q; b and d; I, l, and 1, etc. Other things that improve readability:
  • larger type size
  • shorter lines
  • increased line spacing
  • increased character spacing, i.e., “tracking” (although see Bigelow’s post for conflicting evidence)
  • avoid ALL CAPS and italics
  • avoid word hyphenation and right justified margins
  • avoid centered text
The accessible version of forall x does all these things: Type size is set to 12 pt (not optimal on paper, but since this PDF would mainly be read on a screen, it looks large enough). Lines are shorter (about 40 instead of 65 characters per line). Line spacing is set at 1.4 line heights. Tracking is increased slightly, and ligatures (ff, fi, ffi) are disabled. Emphasis and defined terms are set in boldface instead of italics and small caps. Lines are set flush left/ragged right and words not hyphenated. The centered part headings are now also set flush left. The changes did break some of the page layout, especially in the quick reference, which still has to be fixed. There is also some content review to do. In “Mhy Bib I Fail Logic? Dyslexia in the Teaching of Logic,” Xóchitl Martínez Nava suggests avoiding symbols that are easily confused (i.e., don’t use ∧ and ∨), avoid formulas that mix letters and symbols that are easily confused (e.g., A and ∀, E and ∃), and avoid letters in the same example that are easily confused (p, q). She also recommends to introduce Polish notation in addition to infix notation, which would not be a bad idea anyway. Polish notation, I’m told, would also be much better for blind students who rely on screen readers or Braille displays. (The entire article is worth reading; h/t to Shen-yi Liao.) Feedback and comments welcome, especially if you’re dyslexic! There’s a lot more to be done, of course, especially to make the PDFs accessible to the vision-impaired. LaTeX and PDF are very good at producing visually nice output, but not good at producing output that is suitable for screen readers, for instance. OLP issue 82 is there to remind me to get OLP output that verifies as PDF/A compliant, which means in particular that the output PDF will have ASCII alternatives to all formulas, so that a screen reader can read them aloud. Even better would be a good way to convert the whole thing to HTML/MathML (forall x issue 23). forallxyyc-accessible

Fall 2016 edition of Sets, Logic, Computation

The Fall 2016 edition of the OLP remix Sets, Logic, Computation is ready. As before, it includes the OLP part on sets, relations, and functions; the part on first-order logic (with natural deduction chosen as the proof system); and the part on Turing computability including the unsolvability of the halting and decision problems. The methods chapter on induction and biographies of Cantor, Church, Gentzen, Gödel, Noether, Russell, Tarski, Turing, and Zermelo appear as appendices. At students’ request, problems are now listed at the end of each chapter. Many typos and errors have been corrected, a number of examples and problems have been added, and several proofs rewritten for clarity. I’ve also added chapter summaries and a glossary. There are also a few added sections, notably introduction sections to Chapters 5 and 7, as well as discussion of Russell’s Paradox in both Chapter 1 and 6. You can order a printed copy on Lulu, or download the PDF from the builds page. SLC F16

More Photos of Logicians

As previously mentioned, the Open Logic Project now has a separate repository for photos of logicians to illustrate your OLP-derived materials.  They are automatically included in the biographies that live in content/history.  I’ve just uploaded a whole bunch of photos that don’t have associated biographies (yet).  Some of them are not well-known, even. For the technicalities, I’ll repeat myself from the previous post:
We have a separate repository for photos: We’ve separated them because (a) the licensing issues are more complicated: some of the photos are under copyright, and we wanted everything in the main repository to be available under a Creative Commons license; (b) the main repository would become very large if it included all these pictures. To use the pictures, clone the photos repository into the assets/ subdirectory of your local OLP clone. There’s a PDF with all the photos on the build site.
Tracking down these pictures and getting permissions was (and continues to be) a surprising amount of work.  Thanks to all the people and archives who provided them and granted permissions: the IAS archives, Princeton University Library, Berkeley’s Bancroft Library, the Russell Archives at McMaster, the Archives of the Universities of Warsaw and Wittenberg-Halle, the ILLC, the Austrian National Library, the NSUB at Göttingen, the National Portrait Gallery, the Oslo Museum, Neil Reid (Julia Robinson’s brother-in-law), Libby Marcus (Ruth Barcan Marcus’s daughter), Kim Heffernan (Haskell Curry’s granddaughter), Eckhardt Menzler-Trott, Craig Smorynski, and Peter van Emde Boas. Detailed photo credits are included with the photos.  Thanks also to the Alberta OER initiative for providing some funding to do this.  And last, but not least, thanks to Joel Fuller for doing an awesome job with PhotoShop restoring some of these photos (the original Curry photo, in particular, had a big tear right through the middle)! More to come!