Richard Zach

Logician, historian and philosopher of logic, mathematics, and computability at the University of Calgary (Mohkinstsis/Treaty 7 territory). he/him

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npub1tq96nsuyn6qdtr9u6trkw28nx350g8z589khxetpx7ezg7qlghfqr499nj

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rrrichardzach_at_mathstodon.xyz@mostr.pub

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nprofile1qqs9szafcwzfaqx43j7d93m89reng685r32rjmtnv4sn0v3y0q05t5smla7qv

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npub1tq96nsuyn6qdtr9u6trkw28nx350g8z589khxetpx7ezg7qlghfqr499nj

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Last Notes

2024-09-27 23:03:31

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@npub14dl…aacj not intuitionist if but the next best thing: S4. https://doi.org/10.1017/S1755020308080143

2024-09-09 19:26:43

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@npub1uhn…2f8t I figured; the math and Latex sites are so friendly and helpful usually, it was quite a contrast.

2024-09-09 17:55:07

There's some interest to translate the Open Logic Project. I'm trying to figure out a good workflow on GitHub where the OLP lives. I posted a question on SE https://stackoverflow.com/questions/78966632/translate-book-with-git-github but it got closed since it's not about "software tools primarily used by programmers." What gives?

2024-09-07 17:29:56

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@npub170j…xm06 If you count this (in On the infinite) then it was Hilbert himself in 1926
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2024-09-04 01:54:53

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@npub12fp…dxzc forced march sorites. Epistemicism about vagueness is false not because there are true borderline cases but because the borderlines are knowable after all.

2024-08-19 17:41:58

Hanging out here for a week with a bunch of proof theorists
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2024-08-16 07:43:15

The display on "science in 1920s Vienna" at #wienmuseum: just the entire Vienna Circle. 10/10, no notes
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2024-08-02 07:57:35

Carnap, 30% off
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2024-07-18 22:01:31

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Relatedly, why go to all this trouble to get an example of a mathematical claim where \(A \lor \lnot A\) fails (\(A\) is undecided) but \(\lnot\lnot A \to A\) holds? Isn't this true for every \(A=\forall x P(x)\) where \(A\) is an unsolved question but \(P(n)\) is decidable for each particular \(n\), i.e., we also have \(\forall x(A(x) \lor \lnot P(x))\) (say, Goldbach)?

2024-07-18 21:57:33

Constructive mathematicians (esp. intuitionists): Why does Brouwer say in https://www.jstor.org/stable/20488578 on p. 115 that \(\lnot\lnot s_f \to s_f\)? (Like is this so obvious it needs no explanation and I'm just dense?)
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2024-06-20 23:59:17

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@npub18np…67wx hope it's useful!

2024-06-05 19:20:29

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@npub1ga0…ht9m I suspect this was the whole idea behind Logo https://en.wikipedia.org/wiki/Logo_(programming_language)

2024-04-19 16:08:00

RIP Newton da Costa, pioneer of paraconsistent #logic

2024-03-24 22:44:10

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Bill’s work up until 1980 concentrated on proof theory, specifically cut-elimination, functional interpretations, the ε-substitution method, type theory and lambda calculus. In Tait (1966), he proved the consistency of second order logic, settling the Takeuti conjecture positively. (Prawitz and Takahashi independently settled Takeuti’s conjecture for the full simple theory of types a year later.)

2024-03-24 22:43:18

W. W. Tait, eminent proof theorist and philosopher of math, died on March 15. #logic https://richardzach.org/2024/03/w-w-tait-1929-2024/
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2024-03-18 19:57:16

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@npub150t…ravx @npub1aa3…zykt Canada is feeling left out. Though we are much further south than all these places we can compete on temperature!

2023-12-20 17:04:15

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@npub18np…67wx humberstone

2023-12-20 15:43:20

Lolz #logic
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2023-12-19 13:35:26

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@npub14ly…wpkh :⁠'⁠(

2023-11-24 04:13:19

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@npub12fp…dxzc is this the same people? https://youtube.com/@TheKlein3Group

2023-11-09 00:41:24

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@npub12p6…77s3 Tatort

2023-10-20 23:33:01

TIL that the Andrey Andreyevich Markov of Markov chains ≠ the Andrey Andreyevich Markov of the Markov rule

2023-10-15 22:05:12

Do you use #TexLaTex for natural deduction proofs? Selinger's fitch.sty 1.0 beta ... Would appreciate testing and feedback https://github.com/OpenLogicProject/fitch/releases/tag/v1.0-beta2 #logic

2023-09-17 02:25:21

I posted a list of corrections to the proof theory book: https://richardzach.org/2021/08/an-introduction-to-proof-theory-normalization-cut-elimination-and-consistency-proofs/ #logic #proofTheory
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2023-09-09 16:33:26

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@npub1npq…2fdx the cross poster you advertise has shut down

2023-08-25 16:55:53

My article with @npub18h7…tgdq on where we get the disjunction symbol ∨ from is now officially out in the Review of Symbolic Logic. Open access, read it here: https://doi.org/10.1017/S1755020321000587 #logic #history #histsci #histmath
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