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Posts by Richard Zach

Portraits of members of the Vienna Circle: 
Gustav Bergmann
Rudolf Carnap
Herbert Feigl
Philipp Frank
Kurt Goedel
Hans Hahn
Olga Hahn-Neurath
Béla Juhos
Felix Kaufmann
Viktor Kraft
Karl Menger
Richard von Mises
Otto Neurath
Rose Rand
Josef Schächter
Moritz Schlick
Olga Taussky-Todd
Friedrich Waismann
Edgar Zilsel

Portraits of members of the Vienna Circle: Gustav Bergmann Rudolf Carnap Herbert Feigl Philipp Frank Kurt Goedel Hans Hahn Olga Hahn-Neurath Béla Juhos Felix Kaufmann Viktor Kraft Karl Menger Richard von Mises Otto Neurath Rose Rand Josef Schächter Moritz Schlick Olga Taussky-Todd Friedrich Waismann Edgar Zilsel

Places of the Vienna Circle. An online exhibit by the City of Vienna library and the Institute Vienna Circle online-ausstellungen.wienbibliothek.at/wiener-kreis/en/overview...

1 month ago 1 2 0 0
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DRAFT: A Formally Verified Constructive Proof of the Consistency of Peano Arithmetic Using Ordinal Assignments Gentzen's 1936 proof of the consistency of Peano Arithmetic was a significant result in the foundations of mathematics. We provide here a modified version of the proof, based on Gödel's reformulation, and including additional details and minor corrections which are necessary to definitively prove the well-foundedness of the cut-elimination argument in a constructive environment. All results have been verified using the Coq theorem prover. NOTE TO READERS 26 February 2026: this is a draft which we had intended to submit to the Journal of Automated Reasoning with no particular time-line in our minds as the work was completed as part of Aaron's honours project at ANU in 2023. For that reason, we have used the Springer style files. We are putting it on arxiv as there appears to be some interest in this work as indicated by a post to https://proofassistants.stackexchange.com/questions/6462/how-far-is-gentzens-consistency-proof-of-peano-arithmetic-from-being-formalized in early February 2026. The Coq code is available here: https://github.com/aarondroidbryce/Gentzen/tree/master

Aaron Bryce and Rajeev Goré have formalized Gentzen's consistency proof for PA in Coq/Roqc https://arxiv.org/abs/2603.00487 This finishes an attempt by Morgan Sinclaire scholarworks.boisestate.edu/cgi/viewcontent.cgi

1 month ago 0 1 0 0
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The Man Who Stole Infinity | Quanta Magazine In an 1874 paper, Georg Cantor proved that there are different sizes of infinity and changed math forever. A trove of newly unearthed letters shows that it was also an act of plagiarism.

So turns out Cantor stole the proof that \\(\mathbb{R}\\) is uncountable from Dedekind www.quantamagazine.org/the-man-who-stole-infini...

1 month ago 20 7 2 4

"Again" because this happened already once in 2008, when all editors resigned and founded the Review of Symbolic Logic. But that's not diamond open access while the new Philosophical Logic is!

4 months ago 5 0 0 0
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Flagship Springer Nature journal flips to diamond open access at the OLH We’re excited to announce the launch of a major new journal, following news of another mass editorial resignation (read open letter) at Springer Nature. This week, the Editors-in-Chief and Associate …

The Journal of Philosophical Logic is dead (again!?). Long live Philosophical Logic! https://www.openlibhums.org/news/875/

4 months ago 28 16 1 3
Original post on mastodon.social

In case you missed it, Quote Posts are live on mastodon.social and mastodon.online — let us know what you think!

This feature has been a long time coming because we wanted to take the time to do it right. Part of that process was sharing our work and getting feedback along the way […]

6 months ago 3 38 6 1
A rectangular black sticker, with yellow writing, saying “the only good system is a type system” with a centred lower case lambda in a circle.

A rectangular black sticker, with yellow writing, saying “the only good system is a type system” with a centred lower case lambda in a circle.

The anarchist type theorists are in evidence along Riverside Walk in Dundee.

#typetheory #dundee

9 months ago 1 8 1 0
Picture of (from left) Jack MacIntosh, John Heintz, H.N. Gupta, Alfred Tarski, Brian Chellas, Verena Huber-Dyson, and Bob Woodrow in evening wear.

Picture of (from left) Jack MacIntosh, John Heintz, H.N. Gupta, Alfred Tarski, Brian Chellas, Verena Huber-Dyson, and Bob Woodrow in evening wear.

Here he is in 1982 at Tarski's honorary degree ceremony at the University of Calgary

9 months ago 2 1 0 0
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# Remembering Robert Woodrow Feature June 20, 2025 Issue Feature June 2025 (Vol. 2, No. 24) Issue Contents June 20, 2025 Issue : Vol. 2, No. 24 Feature Remembering Robert Woodrow CMS Meetings 2025 CMS Winter Meeting, Dec 5-8 | Save the Date! 2025 CMS Winter Meeting | Call for Education Sessions 2025 CMS Winter Meeting | Call for Scientific Sessions Announcements International Congress of Mathematicians | July 23 - 30 , 2026 — ICM Call for Proposals: BIRS-MATRIX Tandem Workshop (November 22-27, 2026) Proceedings A: Mathematical theory and applications of multiple wave scattering 2025 CMS Summer Ottawa Math Camp | Registration Now Open Calls for Nominations Call for Nominations: 2026 David Borwein Award | Deadline November 15, 2025 Call from the International Prize Committee — Javad Mashreghi Call for Nominations: 2026 Research Prizes | Deadline September 30, 2025 Call for Nominations: Editor-in-Chief (EIC), Crux Mathematicorum | Deadline July 15, 2025 CMS Student Committee Connect with us on Discord! — Student Committee of the CMS The Canadian Mathematical Society (CMS) is deeply saddened to announce the unexpected passing of Dr. Robert Woodrow on June 10, 2025, shortly after returning to Calgary from the CMS Summer Meeting. He was deeply engaged in every facet of the academic community throughout both his career and retirement. Dr. Woodrow was involved with the CMS for over 45 years, serving in many capacities and most recently, and for over ten years, as the Chair of the Canadian Open Mathematics Challenge (COMC). He was a pillar whose dedication, insight, and kindness left an enduring and profound impact on all of us. Members of our community have shared their heartfelt memories of him: “ _Robert Woodrow was a true asset to the CMS and a dedicated member since 1981. His commitment was further demonstrated through his invaluable contributions to the Board of Directors and numerous committees._ _Robert dedicated the last decade of his efforts specifically to competitions and the student committee, particularly as a pivotal chair of the COMC committee. He generously invested countless hours in this competition, through proctoring and rigorously vetting exams, leading the COMC committee, and providing exceptional leadership for our largest math competition._ _Robert will be truly missed and remembered fondly by all staff and everyone who had the privilege of working with him. We will miss his dedication and unwavering enthusiasm for math competitions. We’ll also deeply miss his presence at CMS Meetings; he was a truly dedicated champion of the CMS_.” – Dr. Termeh Kousha, Executive Director, Canadian Mathematical Society “ _Dr. Robert Woodrow was a very special colleague and a tremendous friend of the Canadian Mathematical Society. As a former Executive Director of the CMS, I was fortunate to work with Robert in many different ways. He was a member of the CMS for more than 45 years and he was always ready to help whenever asked. His tireless efforts, infectious personality, generosity and commitment to the work of the CMS was an inspiration to all. Of particular note was his service as Chair of the Canadian Open Mathematics Challenge Committee, the Faculty Advisor to the CMS Student Committee, a member of the CMS Advancement of Mathematics Committee and as the Olympiad Editor of Crux Mathematicorum. Robert was awarded the Society’s Distinguished Service Award in 2010 and appointed a CMS Fellow 2018. His dedication and unwavering commitment to the Society continued until only a few days before his untimely passing on June 10, 2025. The Society has lost one of its most respected and valued members and I have lost a remarkable friend. It is hard to imagine the CMS without Dr. Robert Woodrow. He will be greatly missed by all who knew him_.” – Dr. Graham Wright, Former Executive Director of the Canadian Mathematical Society “ _Robert was truly an extraordinary, kind and caring person, who spent his life to his last hours serving the mathematical community, in particular its younger members. His actions clearly came from his heart. I am extremely grateful to have had the honour to work with him and benefit from his wisdom and experience in administering the COMC and other competitions. He was very generous with his time and always willing to help ensuring each student was treated fairly. He clearly enjoyed what he did and it was a joy to work with him_.” – Dr. Dorette Pronk (Dalhousie), Chair, Math Competitions Committee “ _A gregarious host, a lively and generous table companion, a stimulating research collaborator, and a colleague with a decades-long dedication to math contests and other math enrichment activities: Robert was each of these, and in each case no-one could have asked for more._ ” – Dr. Bill Sands (University of Calgary) The CMS sends its heartfelt condolences to Dr. Woodrow’s family and friends. His absence leaves a void that will be deeply felt across our community, and his legacy of generosity, leadership, and unwavering dedication to mathematics will continue to inspire us for many years to come. **An extended tribute to Dr. Woodrow will be featured in the September issue of the _CMS Notes_. If you have photographs or personal memories you would like to contribute, please email them to ****communications@cms.math.ca****.** **For more information, please contact:** Dr. Claude Laflamme Professor Emeritus University of Calgary laflamme@ucalgary.ca| Dr. Bill Sands Professor Emeritus University of Calgary sands@ucalgary.ca| CMS Executive Office cms@cms.math.ca ---|---|--- Share on Facebook Share on email Post this on X/Twitter Instagram Send to printer

RIP Robert Woodrow

mathmatters.cms.math.ca/en/article/remembering-r...

9 months ago 2 2 1 0
Original post on mathstodon.xyz

Preparing for Fall 2025

Most of the Open Logic textbooks have seen lots of changes from the versions currently available in hardcopy, so it's time to refresh those to Fall 2025 editions. These will incorporate all the corrections reported by readers since at least 2023 and in many cases going […]

9 months ago 4 5 0 0
Original post on mathstodon.xyz

Preparing for Fall 2025

Most of the Open Logic textbooks have seen lots of changes from the versions currently available in hardcopy, so it's time to refresh those to Fall 2025 editions. These will incorporate all the corrections reported by readers since at least 2023 and in many cases going […]

9 months ago 4 5 0 0
Original post on hcommons.social

Last week was all type theory, all the time. *This* week I get to change gears, and take part in the 50th Annual Conference of the Society for Exact Philosophy. I’m especially looking forward to Day 2, which is devoted to the work of our sorely-missed colleague, Aldo Antonelli, who passed away […]

10 months ago 1 4 1 0

@df LOC says this is a Robert W. Prevost

11 months ago 0 0 0 0

@df suspect that's a different Robert Prevost. I don't think Leo was ever at Oxford and in 1985 he was in Peru

11 months ago 0 0 2 0
Original post on flipboard.social

In the U.S., there's a "secret" form of media: radio reading services, where volunteers read aloud the text of newspapers, books and magazines. These used to be broadcast on "sidebands" — little hidden side pockets of public radio or TV stations' airwaves — for which folks needed a special radio […]

11 months ago 1 13 0 0
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amen zwa, esq. (@AmenZwa@mathstodon.xyz) 4.58K Posts, 330 Following, 346 Followers · I am an ordinary man. So, I am unique up to isomorphism. 🇺🇸 JD ⊥ MSCS Ω BSEE 🇺🇦 Washington, DC

@AmenZwa
Logisim port to browser "using a version of OpenJDK that runs in WebAssembly"
https://drs.software/blog/announcing-logisim/
https://logisim.app/
via
mathstodon.xyz/@regehr@mastodon.social/...

11 months ago 1 4 0 0

Fuck Ayn Rand (1905–1982)

#philosophy

1 year ago 1 4 0 0
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MC-PMP-Brussels-2025 About

Absolutely thrilled to be delivering this year's Philosophy of Mathematical Practices Masterclass at Vrije Universiteit Brussel, 18-20 June. Grad students and postdocs, come and talk with me about materials, institutions, and critical contexts!
https://sites.google.com/view/mc-pmp-brussels-2025

1 year ago 2 3 0 0

@consequently "modal industrial complex"

1 year ago 1 1 0 0
Original post on fediscience.org

Today the editorial board of _Mathematical Logic Quarterly_ (pub'd by @Wiley) resigned and launched a new #DiamondOA journal on the same topics.
open-access.network/services/news/artikel/ru...

See their open letter announcing their resignations and plans for […]

1 year ago 17 3 0 4
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ZML - Zeitschrift für Mathematische Logik und Grundlagen der Mathematik ZML: Zeitschrift für Mathematische Logik und Grundlagen der Mathematik is an electronic Diamond Open Access research journal in mathematical logic publishing original research papers in all areas of mathematical logic.

The Mathematical Logic Quarterly is dead. Long live the Zeitschrift für mathematische Logik und Grundlagen der Mathematik! https://zml.international/

1 year ago 1 3 0 0

Notations for neurodiverse learners - extensive discussion of effects of mathematical notation

www.sciencedirect.com/science/article/pii/S073...

1 year ago 1 2 0 0

I wrote up what I learned converting an open textbook in LaTeX to HTML and making it accessible richardzach.org/2025/03/accessible-open-... #TexLaTeX #OER #accessibility #blind

1 year ago 3 6 0 0
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@isAdisplayName I'm sure it likes watching birds, just like avid birder Curry

1 year ago 0 0 0 0
Original post on flipboard.social

David Johansen, who fronted the legendary 1970s proto-punk band New York Dolls and also recorded under the pseudonym Buster Poindexter, has died at 75, his representative confirmed. Johansen was the subject of a documentary from directors Martin Scorsese and David Tedeschi, “Personality Crisis […]

1 year ago 3 0 0 0
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papers/LISP I Programmers Manual - IBM 704 - 1960.pdf at master · Luiz-Monad/papers Contribute to Luiz-Monad/papers development by creating an account on GitHub.

https://imgs.xkcd.com/comics/lisp_cycles.png

OTD 1960: LISP I Programming manual is published: github.com/Luiz-Monad/papers/blob/m...

1 year ago 0 1 0 0
Original post on hcommons.social

Next week, I’m heading off to North America for a few talks. (I’d committed to these talks before last year’s election and I have mixed feelings about the trip, but I’m going, nonetheless.)

If you're in the LA area, in or around Calgary, or New York, and you’re into philosophical logic, why […]

1 year ago 0 3 1 0
Original post on hcommons.social

I'm delighted to share that next month, I’ll be in Canada, giving the 2024-25 Calgary Mathematics & Philosophy Lecture. I’ll be talking about mathematical practice, proof assistants, and meaning. If you’re in that part of the world on March 13, I’d love to see you there! […]

1 year ago 3 4 0 0

Truly remarkable stuff in this thread.

1 year ago 4 2 0 0