Geek stuff

Setting tableaux using prooftrees.sty

[Updated] The first edition of IFL was typeset using FrameMaker (long since defunct on a Mac), so I’m having to LaTeX the second edition from scratch. I’m using Clea Rees’s fairly new package prooftrees.sty for downward-branching tableaux, a.k.a. truth-trees, since this seems to give the right level of control over trees, allows line numbering and line comments, and beats other options by some way.

I have therefore added a link on the LaTeX for Logicians page on tree proofs to a document on setting tableaux using this package [New version 12 Feb] This contains some initial notes on using the package and also gives a few examples.

I’d be very happy to hear about any tips and tricks for this package from other users that could also be shared at LaTeX for Logicians. (And of course, all other suggestions and  corrections for L4L are always welcome!)

Generating truth-tables in LaTeX

I have just added to the “Logicians’ miscellany” page of LaTeX for Logicians a new heading “Help for generating truth-tables”. There is now a link there to a Truth Table Generator webpage by Michael Rieppel. This page contains a JavaScript program which will generate a truth table given one or more well formed formulas of sentential logic, and provide you with LaTeX source for the table.

Thanks to Sara Uckelman for the pointer to this. Any other recommendations for similar or even better resources?

Duet Display again


I posted about this six months ago. But let me repeat myself, by way of a public service announcement!

If you have e.g. a MacBook of some description (or indeed a Windows machine), and an iPad, you can use the iPad as an additional display. Duet Display works over a USB cable, so it is very much smoother and vastly less flakey in operation than old implementations of the general idea using e.g. local wifi. OK, it won’t magically increase your “productivity” but it assuredly reduces the irritations of window-juggling when working. Above, there’s my current source code for a LaTeX chapter in a TeXShop window on the left of the 15″ MBP screen, the PDF of the book on the right — and off-loaded to a standard-sized iPad, the TexShop console and a BibDesk window. Of course you could put something more distracting on the secondary screen!

Once you’ve told Duet Display how you have placed your iPad and laptop relatively to each other, the cursor magically goes from screen to screen (and the current menubar moves with it), just as with a more standard multi-monitor set-up. It really does work a treat and is extremely stable. And by the way, you can hit the home button on the iPad to navigate to other open apps in the usual way, and then return to Duet Display to pick up where you left off.

You can get Duet Display for the iPad from the app store, and then download the free OSX or Windows companions from their site. If you don’t know it, a very warmly recommended bargain.

[Added: Updating to MacOS Sierra hasn’t actually broken Duet Display, but leads to some unwanted effects – apparently Apple’s fault. Still useable, but not as seamlessly smooth.]

Reaching peak Apple: the Macbook 2016

I have not wanted to post about the really pretty miserable political news even though it has been much occupying my thoughts (for I have nothing new or insightful to add about Brexit,  about the incompetent narcissist supposedly leading the Labour Party, or about the new UK government, let alone about the disasters in the wider world). And I’m afraid that spending a lot of time tinkering with little presentational issues in the early chapters of my introductory text book as I slowly work towards a second edition doesn’t exactly provide inspiration for exciting logical posts here either.

So let me tell you about my new MacBook instead.

Headline news: if you are thinking of splurging out on new Apple kit, the revised 12″ Macbook is just terrific. Go for it.

Slow news: I’d been using as my portable (for libraries, cafés, sofa-surfing on my lap) a Macbook Air, now approaching five years old. Still a great bit of kit. But, and it’s quite a big ‘but’ for someone spending a lot of time writing, the on-screen text on the MBA now does seem decidedly blurry. Compared with modern retina screens on my iPhone, iPads, and a big and not-very-portable MacBook Pro used as my main home machine — yes, I really am reaching peak Apple here  — the elderly MBA screen is just not so great. Hence, initially pretty much for that reason alone, when a larger-than-expected royalty cheque arrived, I splashed out on the recently revised 12″ MacBook. Space gray, since you asked.

Six weeks in, I’m more than delighted. Some have commented adversely on the keyboard. But unless you are a very heavy-handed typist, you should find it excellent. Despite its different feel, going from this keyboard to the MacBook Pro and back really presented zero problem after just a day or two ‘s use. The screen is simply amazing. The lack of ports is also no problem at all for me, since all my work files live in DropBox, and everything else lives in various clouds too. And — now this was a very big surprise — the added portability (and added ease of use on a lap!) seems completely out of proportion to the actual change in size and weight compared to the MBA. Finally, the MacBook is even more gorgeous than the MBA, and I think aesthetics matter if you are spending so much time up close and personal with something!

Whether it would suit you as a sole machine, I can’t say: read the usual forums for advice on that. But for anyone looking for a very portable second machine to take out and about, this works a treat in every way. You’d have to be very hard to please not to be delighted!

Nerdy note: I initially got the entry-level model, but then returned it for the upgrade to the fastest m7 chip which does make a noticeable difference working with LaTeX: I’d recommend the small extra outlay for that reason. More on this, with some timings, here.

New package for setting proof tableaux

Suppose you want to typeset (using LaTeX of course) a proof tree that looks something like this: Screengrab copy

Maybe that’s an answer to some exercise for students, which is why you want a tree fully annotated with line numbers, justifications on the right, and justifications too for closing off branches. Previously, getting in all that detail using available LaTeX resources would have been tricky. Now help is at hand. There is a very nice new package prooftrees.sty which will enable you to generate that output easily. And, of course, generate simpler results too, without line numbers and/or justifications, if that’s what you want. The package seems very flexible and to provide, at last, the kind of purpose-built-for-logicians tool that we have needed for a long time. So all credit to Clea Rees for her work on this.

Apple nerd note: Duet Display

If you have e.g. a MacBook of some description (or indeed a Windows machine), and an iPad, you can use the iPad as an additional display. Duet Display works over a USB cable, so is much much smoother and less flakey in operation than old implementations of the general idea using Bluetooth. Works a treat. OK, it won’t magically increase your “productivity” but it assuredly reduces the irritations of window-juggling when working. You can get Duet Display on the app store or from their site. If you don’t know it, a warmly recommended bargain.

LaTeX for Logicians refresh

As a bit of distraction from all the other logic-related things I really ought to be doing, I’ve just been tidying the LaTeX for Logicians pages for the first time for a good while. After a bit of re-arrangement here, some renewing of broken links there, then working a few suggestions in comments (thanks!) into the main pages, and doing some searching on e.g. tex.stackechange, here we are.

Whatever one’s issues and reservations about LaTeX for more general use, it is still surely quite invaluable for logicians. So do please let me know, then, how these pages can be improved, what new LaTeX packages of use to logicians that I have missed, etc.

The Open Logic Text

As you will very probably have already seen, The Open Logic Project (a team of serious and good people) has now made available an early public version of an open-source collaborative logic text, somewhat ploddingly called the Open Logic Text. 

There are two things to comment on here (eventually!), namely the Text itself — or at any rate, the current snapshot of an evolving text — and the open-source nature of the enterprise.

At a first quick glance, the Text does look rather uneven: there are 77 pages on first-order logic and beyond (some at quite an elementary level), 100 pages on computability, incompleteness, etc. (this looks like a solid graduate course), and then just 21 pages on sets (at a very much lower level of sophistication). Still, this is obviously exactly the sort of thing that should be covered in the Teach Yourself Logic Study Guide. So when I’ve had a chance to take a serious look, I’ll report back with my two pennies’ worth, maybe in a mid-year update to the Guide.

You can download the current version as a PDF. But as the Project site says of the Text,

… you can download the LaTeX code. It is open: you’re free to change it whichever way you like, and share your changes. It is collaborative: a team of people is working on it, using the GitHub platform, and we welcome contributions and feedback.

I will be really interested to see how this pans out in practice. Using GitHub is a notch or three above my current nerdiness grade. But I simply don’t know if this is me just not keeping up with everyone — or whether it is pretty typical for logicians to know a smidgeon of very basic LaTeX, with that being about their geek limit. Maybe, at least as a bit of exercise to keep the brain from entirely rusting up, I should take a look at this GitHub malarky about which I’ve heard tell before (any useful pointers to an idiot’s guide?). Then I could also report back about how the collaborative aspect looks to a complete beginner. Again, watch this space.

Cloud storage made easy: with a bit of helpful geekiness

This may be useful for someone who like me doesn’t keep up with every geeky development, and so can miss out on things (thanks to Keith Frankish for the heads-up).

OK: you know that it makes sense to back up a lot of your stuff “in the cloud” (we’ll set aside questions of security and sensitive personal stuff — I’m talking about all the rest).  At this late date, you don’t need a lecture about backing up from me!  And you very likely know about the delights of Dropbox. But maybe you are running out of free space. Or you just want to be doubly secure. What to do (without paying out for a “premium” account)?

Well, you could try the new cloud storage service at, which is about two months old, and aims to muscle in on Dropbox. Sign up by clicking on this link and you’ll get 20GB of free storage [and — full disclosure — I get 5GB extra storage for every sign-up if you do the email verification to kick things off]. I suspect this is a time-limited early-adopters generous offer to help spread the word. Give it a whirl, as you’ve nothing to lose. Signing up involves no more than choosing a password, downloading an app, and clicking a verification link in an email — nothing scary.

Then what happens? A folder “Copy” is installed, and while the app is running what you put in the folder gets automatically copied to the cloud  (you can sync across machines, and can access contents from the cloud from mobile apps — the usual kind of thing you’d expect). Why not give it a go, to increase your cloud storage?

“Ah, but I don’t want to muck about with my folder system and/or I’ve already got a Dropbox folder for stuff I want to backup in the cloud”.  No problem. Here’s the promised helpful geekiness:  you don’t actually have to move files or folders into the Copy folder — you can just put into that folder a symbolic link to anything you want backed up. E.g. a symlink to your “Current work” folder, or to your iPhoto library, or whatever.  (“What’s a symbolic link?” Not an alias — you can Google the difference. The key thing is that a symlink is transparent to Copy and to Dropbox, so putting a symlink into your Copy and/or your Dropbox folder is as good as putting a copy of the file into the folder, except it takes up no space on your hard drive and the copy changes when the file does. Mac users can make symbolic links exceedingly easily using this. )

You can thank me later …

LaTeX for Logicians — any suggestions?

I’ve just been (belatedly) sprucing up LaTeX for Logicians again, and repairing a regrettable number of broken links. Some of those broken links were due to changes at CTAN;  but a few were due to people who had useful pages on their personal websites now apparently going off the radar.

The only new addition is a link on the Natural Deduction page to the CTAN archive for lplfitch, a package “for typesetting Fitch-style proofs a la Language, Proof, and Logic, by Jon Barwise and John Etchemendy.” (It was originally written by John Etchemendy, with modifications by Dave Barker-Plummer and Richard Zach, and looks excellent.)

I know a lot of people out there use LaTeX for Logicians (for example, that page of info about Natural Deduction packages was visited over 7000 times in the first six months of the year). And I very rarely get any corrections, suggestions for additions, etc. Which I guess is a good sign (presumably the pages are quietly succeeding at doing what they are intended to do). However, if you’ve been meaning to send me any ideas, requests, pointers towards new stuff, etc., now’s the time, while L4L is at the front of my mind for a day or two.  So, over to you …


Scroll to Top