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Logic Matters @logicmatters.bsky.social · 29/09/2026

At the end of the live broadcast at 57.39, I was then completely poleaxed by Elisabeth's encore ... if I had been in the hall would I have held it together ...?

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Logic Matters @logicmatters.bsky.social · 29/09/2026

There followed Chopin's Fantasy in F minor Op. 49. Beautifully played of course, but maybe not a piece particularly to my taste. Perhaps as I listen again (and again?) Elisabeth will convince me -- very happily, we can download the concert for a month (www.bbc.co.uk/sounds/play/...)

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Logic Matters @logicmatters.bsky.social · 29/09/2026

Elisabeth began with Mozart, this time the Piano Sonata in F, K332. Next she played numbers II to VI of Bartók's 14 Bagatelles Op. 6, and then XV 'Le baiser de l’Enfant-Jésus' from Messaien's *Vingt regards sur l’Enfant-Jésus* (the Bartók and Messaien were both new to me, and I was much taken).

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Logic Matters @logicmatters.bsky.social · 29/09/2026

Not the greatest month. And hence it wasn't possible to get to London to attend Elisabeth Brauß's lunchtime concert in the Wigmore Hall Autumn International Piano Festival at Wigmore Hall on Monday. But -- a delight -- the concert was broadcast live on BBC Sounds. #classical #mozart

Elizabeth Brauß playing at an earlier Wigmore Hall recital

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Logic Matters @logicmatters.bsky.social · 09/09/2026

A quick reminder for new semesters/terms. There are now FIVE Rig Red Logic Books free to download. My (ex-CUP) Intro to Formal Logic, and Gödel's Theorems. The shorter Gödel Without Tears. A Study Guide to Math Logic. And Introducing Category Theory. logicmatters.net/books/ #philsky #mathsky

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Logic Matters @logicmatters.bsky.social · 09/09/2026

Three (non-logic) book recommendations -- James Marriott's *The New Dark Ages*, Lettice Cooper's *Fenny*, Kathleen Jamie's *The Overhaul*. logicmatters.net/blog/recent-... 💙📚 #booksky

logicmatters.net

Three reading recommendations – Logic Matters

Three non-logic books to read!

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Logic Matters @logicmatters.bsky.social · 06/09/2026

I am so late to discover Kathleen Jamie. But her *Overhaul* is wonderful, isn't it? 💙📚 #booksky

Cover of poetry collection, showing beached boat

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Logic Matters @logicmatters.bsky.social · 06/09/2026

As announced before, I am beginning slowly to revise the 2022 *Beginning Mathematical Logic* Study Guide. Here is the third updated chapter -- this one is on proof theory. (Not major revisions, but improved, I hope!) logicmatters.net/tyl/pdfs/Pro... #philsky, #mathsky

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Logic Matters @logicmatters.bsky.social · 29/08/2026

As announced before, I am beginning to revise the 2022 Beginning Mathematical Logic Study Guide. Here is the second updated chapter: on computable functions, formal arithmetics, and Gödel’s theorems. Enjoy! logicmatters.net/tyl/pdfs/Ari... #philsky, #mathsky

logicmatters.net

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Logic Matters @logicmatters.bsky.social · 23/08/2026

I hadn’t listened to this recording for perhaps a couple of years, but I was absolutely transfixed, hearing it again. Utterly extraordinary music, stupendously well played. Unmissable. 2/2

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Logic Matters @logicmatters.bsky.social · 23/08/2026

In the most recent issue of the BBC Music Magazine, the “Building a Library” feature is devoted to Shostakovich’s much played, much recorded, 8th String Quartet. And the chosen top recommended recording is – not surprisingly – the astonishing performance by the Pavel Haas Quartet. 1/2

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Logic Matters @logicmatters.bsky.social · 14/08/2026

Characteristically interesting new blogpost by Tim Gowers, "What sort of maths are LLMs good at?" gowers.wordpress.com/2026/08/12/w... #MathSky

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Logic Matters @logicmatters.bsky.social · 13/08/2026

I am starting to update the *Beginning Mathematical Logic* Study Guide (logicmatters.net/tyl) Here's the first newly revised chapter, a list of recommended (and not-recommended) reading on First Order Logic, logicmatters.net/tyl/pdfs/FOL... Suggestions? Corrections? #MathSky #PhilSky

logicmatters.net

The Study Guide and Book Notes – Logic Matters

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Logic Matters @logicmatters.bsky.social · 07/08/2026

At the gentler end of the spectrum, there are my own notes *Introducing Category Theory*, freely downloadable of course but also available as a minimum cost paperback. Some students do like the book! Do check out whether it might work for you. #MathSky

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Logic Matters @logicmatters.bsky.social · 07/08/2026

A reminder, if you are taking a category theory course next term/semester. There is a page of links to reasonably accessible and (legally!) freely downloadable lecture notes etc. at logicmatters.net/categories. You could very well find there some helpful preliminary/parallel reading. #MathSky

logicmatters.net

Category theory: online lecture notes, etc. – Logic Matters

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Logic Matters @logicmatters.bsky.social · 16/07/2026

Pleased to see that the Guardian’s most viewed piece this morning is ‘Zara death pants’: are these the world’s most dangerous trousers? Shows a proper sense of priorities….

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Richard Pettigrew @wiglet1981.bsky.social · 08/07/2026

I always like the end of the famous passage from William James’s Will to Believe on this…

Believe truth! Shun error!—these, we see, are two materially different laws; and by choosing between them we may end by coloring differently our whole intellectual life. We may regard the chase for truth as paramount, and the avoidance of error as secondary; or we may, on the other hand, treat the avoidance of error as more imperative, and let truth take its chance. Clifford, in the instructive passage which I have quoted, exhorts us to the latter course. Believe nothing, he tells us, keep your mind in suspense forever, rather than by closing it on insufficient evidence incur the awful risk of believing lies. You, on the other hand, may think that the risk of being in error is a very small matter when compared with the blessings of real knowledge, and be ready to be duped many times in your investigation rather than postpone indefinitely the chance of guessing true.
I myself find it impossible to go with Clifford. We must remember that these feelings of our duty about either truth or error are in any case only expressions of our passional life. Biologically considered, our minds are as ready to grind out falsehood as veracity, and he who says, "Better go without belief forever than believe a lie!" merely shows his own preponderant private horror of becoming a dupe. He may be critical of many of his desires and fears, but this fear he slavishly obeys. He cannot imagine any one questioning its binding force. For my own part, I have also a horror of being duped; but I can believe that worse things than being duped may happen to a man in this world: so Clifford's exhortation has to my ears a thoroughly fantastic sound. It is like a general informing his soldiers that it is better to keep out of battle forever than to risk a single wound. Not so are victories either over enemies or over nature gained. Our errors are surely not such awfully solemn things. In a world where we are so certain to incur them in spite of all our caution, a certain lightness of heart seems healt…

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Logic Matters @logicmatters.bsky.social · 07/06/2026

Wonderful concert by the Pavel Haas Quartet at Wigmore Hall, playing a selection of Dvorak's Cypresses, and then Dvorak's "American Quaret". After the interval they are joined by Boris Giltburg and Petr Ries to play Schubert's Trout Quintet. Stunningly good. www.youtube.com/watch?v=Qj2c...

youtube.com

Pavel Haas Quartet, Boris Giltburg and Petr Ries | Dvořák and Schubert - Live from Wigmore Hall

YouTube video by Wigmore Hall

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Logic Matters @logicmatters.bsky.social · 06/06/2026

I'd say that this was quite extraordinarily good -- except that the Pavel Haas Quartet are always exceptional. Pavel Haas Quartet, Boris Giltburg and Petr Ries | Dvořák 'American' Qt and Schubert 'Trout' -- www.youtube.com/live/Qj2cPuj... via @YouTube

youtube.com

Pavel Haas Quartet, Boris Giltburg and Petr Ries | Dvořák and Schubert - Live from Wigmore Hall

YouTube video by Wigmore Hall

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Logic Matters @logicmatters.bsky.social · 06/06/2026

logicmatters.net now points to a new, minimalist, GitHub-hosted static site. Oh what nerdy fun migrating from a bloated Wordpress version (with more than a little help from my friend Claude). I hope note too many links have got broken in the transition -- let me know about annoying cases!

logicmatters.net

Logic Matters

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Logic Matters @logicmatters.bsky.social · 04/06/2026

Yes, of course, the book is freely available online and as a pbk. But many find working from a 500 page PDF irksome, and much prefer a physical book. So please ask your local uni library to order to a hardback (it certainly won’t dent their budgets too much, being listed at $35, £31.50, etc.).

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Logic Matters @logicmatters.bsky.social · 04/06/2026

An inexpensive hardback of Introducing Category Theory was published on June 1st, and is beginning to appear listed on booksellers’ online sites — search with the ISBN 106834671X. #mathsky #philsky

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Logic Matters @logicmatters.bsky.social · 04/06/2026

Yes, of course, the book is freely available online and as a pbk. But many find working from a 500 page PDF irksome, and much prefer a physical book. So please ask your local university library to order to the hardback! -- it won’t dent their budgets too much, being listed at $35, £31.50, etc.

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Logic Matters @logicmatters.bsky.social · 03/06/2026

I'm migrating Logic Matters from an expensively hosted Wordpress incarnation to a freely hosted GitHub site. Wish me luck! Here's a first version -- all comments most welcome. logicmatters.github.io/logic-matter... #philsky #mathsky

logicmatters.github.io

Logic Matters

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Logic Matters @logicmatters.bsky.social · 21/05/2026

The revised/corrected third edition of *Introducing Category Theory* is now available as a paperback. To keep the cost down it is Amazon-only print-on-demand with ISBN 1068346728. Sorry! -- but the PDF remains freely downloadable from logicmatters.net for Amazon refuseniks ...

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John C. Baez @johncarlosbaez.bsky.social · 17/05/2026

I never knew what was so great about the "great icosahedron". Now I do! Take a regular icosahedron whose vertices have coordinates in ℚ[√5]. Apply the nontrivial element of the Galois group: that is, replace √5 by -√5. You get the great icosahedron! (1/n)

A "great icosahedron" - a star-like 3-dimensional shape with the same vertices as a regular icosahedron, but with large pentagram-shaped faces that intersect each other instead of the usual equilateral triangles. That is, each vertex is no longer connected to its 5 nearest neighbors, but instead its 5 second-nearest neighbors.

From here: https://en.wikipedia.org/wiki/Great_icosahedron

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Logic Matters @logicmatters.bsky.social · 18/05/2026

There have been so many moving obituaries and fond tributes. Here, to mark her passing, is Felicity Lott at the start of her stellar career, singing Pamina at Glyndebourne, almost fifty years ago. How joyous.

youtu.be

Bei Männern, welche Liebe fühlen - Die Zauberflöte I Felicity Lott & Benjamin Luxon

YouTube video by L'opera

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Logic Matters @logicmatters.bsky.social · 14/05/2026

There's a newly revised version of my *Introducing Category Theory* notes -- correcting an embarrassing number of typos and a few thinkos in the previous version. A pbk follows, but meanwhile here's a link to the (free!) PDF: www.logicmatters.net/resources/pd... #Mathsky #Philsky

logicmatters.net

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Logic Matters @logicmatters.bsky.social · 20/04/2026

Elizabeth Brauß gave a really wonderful performance of Schubert’s first set of Impromptus at a concert a few years ago. The BBC have broadcast it again. Listen -- it will make your day better! www.bbc.co.uk/sounds/play/... (starting at 5.12.40 in) #Schubert #Piano

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Logic Matters @logicmatters.bsky.social · 07/04/2026

It almost seems a shame to hide the new wallpaper with books ... but needs must! #booksky

Empty bookshelves in newly redecorated room with William Morris wallpaper behind

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Logic Matters @logicmatters.bsky.social · 07/04/2026

A quick blog post commenting on the claim by Alex Oliver and Tim Smiley to have shown that the “easy” direction of Church's Thesis is wrong. I'm not persuaded -- and neither should you be! www.logicmatters.net/2026/04/06/p... #philsky #mathsky

logicmatters.net

Partial functions and Church’s Thesis - Logic Matters

Alex Oliver and Tim Smiley’s magnum opus Plural Logic runs to some 340 pages before the end matter in the second edition. The final chapters are heavy going, involving detailed developments of some cu...

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Frank Beck @diehoren.bsky.social · 24/03/2026

One of my favorite works by Schubert -- his Impromptu No. 3 in G-flat major -- played superbly by German pianist Elisabeth Brauß and posted by German public broadcasting. www.youtube.com/watch?v=4tWc...

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Logic Matters @logicmatters.bsky.social · 17/01/2026

Elisabeth Brauss played Mozart's 23rd Piano Concerto at the Cartagena Festival de Música ten days ago.A terrific performance she evidently much enjoyed. www.youtube.com/watch?v=rX5c...

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Logic Matters @logicmatters.bsky.social · 16/01/2026

This tells you a lot more about LW than about his vary various Cambridge contemporaries.

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Logic Matters @logicmatters.bsky.social · 13/01/2026

There's a new version of my *Introducing Category Theory* now available -- a freely downloadable PDF and also a very-cheap-for-its-size pbk. Enough corrections/improvements to count as a "third edition". For info/link see logicmatters.net/categories Please spread the word! #MathSky #PhilSky

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Logic Matters @logicmatters.bsky.social · 06/01/2026

The second issue of the new Journal for the Philosophy of Mathematics is now online (open access). Includes five pieces on sets and pluralities which (on a quick browse) seem interesting and good. Take a look! #MathSky #PhilSky riviste.fupress.net/index.php/jpm

riviste.fupress.net

Journal for the Philosophy of Mathematics

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Bob Hawkins @bobhawkins.bsky.social · 05/01/2026

Today’s epiphany… here the adoration of the magi by Fra Angelico & Fra Filippo Lippi 1440-60. National gallery of art Washington DC.

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Logic Matters @logicmatters.bsky.social · 28/12/2025

A new blog post about using AI in proofreading the upcoming revised 2nd edition of my category theory book. Might be of interest to other maths writers. www.logicmatters.net/2025/12/28/a... #MathSky

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Logic Matters @logicmatters.bsky.social · 05/12/2025

Oddly the video has disappeared. I do hope not because Elisabeth was herself unhappy with her performance which her audience obviously loved.

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Logic Matters @logicmatters.bsky.social · 05/12/2025

There will be a revised version of my category theory book in January. Mostly minor changes for reader-friendliness. But I have expanded the short chapter on ETCS at the very end of the book into two short chapters. Here's a draft: www.logicmatters.net/resources/pd... Comments very welcome! #MathSky

logicmatters.net

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Logic Matters @logicmatters.bsky.social · 05/12/2025

Wonderful concert by Elisabeth Brauss at Wigmore Hall on Tuesday. Her Beethoven Op. 110 particularly moving -- www.youtube.com/watch?v=Puyd...

youtube.com

Elisabeth Brauss | Beethoven, Grieg, Hans Abrahamsen and Liszt - Live from Wigmore Hall

YouTube video by Wigmore Hall

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Chris Satoor @nieaufgehenderrest.bsky.social · 21/04/2025

Paul Klee The Bounds of the Intellect, 1927

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Logic Matters @logicmatters.bsky.social · 21/09/2025

New double CD of Lea Desandre and Thomas Dunford (and the Jupiter Ensemble) performing Dowland and Purcell. Absolutely superb playing and often extraordinarily moving. (Had the good fortune to see them live at Wigmore Hall last week -- just stunning.)

CD cover ...black and white photo of Lea and Thomas

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Logic Matters @logicmatters.bsky.social · 23/08/2025

CD Forthcoming soon! Love the cover photo :)

Cover of forthcoming CD by the Pavel Haas Quartet

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Logic Matters @logicmatters.bsky.social · 13/07/2025

First 5 star Amazon rating AND first typo report for new edition of *Introducing Category Theory*. Ah well ...

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