# Sheffer stroke before Sheffer: Edward Stamm

It came up in discussion at the Formal Turn conference the other day, so I thought I'd preserve an old Twitter thread here: The first person to publish results on NAND and NOR (Sheffer stroke and Peirce arrow) was the Polish mathematician and Philosopher Edward Stamm (1886–1940). The publication was "Beitrag zur Algebra der Logik … Continue reading Sheffer stroke before Sheffer: Edward Stamm

# New details on why Tarski was reluctant to leave Poland before WWII

Paolo Mancosu has a new paper out in the Journal of Humanistic Mathematics: This article makes available some early letters chronicling the relationship between the biologist Joseph H. Woodger and the logician Alfred Tarski. Using twenty-five unpublished letters from Tarski to Woodger preserved in the Woodger Papers at University College, London, I reconstruct their relationship … Continue reading New details on why Tarski was reluctant to leave Poland before WWII

# Updates to OLP for Fall 2021 edition of Sets, Logic, Computation

In preparation for the Fall 2021 edition of Sets, Logic, Computation, the material in the Open Logic Project has seen […]

# Famous logicians and their inconsistent theories

A couple of days ago, Daniel Litt linked to Patrick Brosnan's computer-verified "proof" of the inconsistency of Peano arithmetic. The proof is correct; I just put it in quotes because it relies on a quirk of the proof verification system used (Metamath), which requires you to explicitly prohibit certain variable substitutions. The axiom of PA … Continue reading Famous logicians and their inconsistent theories

# forall x: Calgary goes international (and other updates)

ICYMI, forall x: Calgary has been translated into German and Portuguese! forall x: Dortmund by Simon Wimmer is the German […]

# MUltlog 1.13 released

MUltlog is a Prolog program that converts a specification of a finite-valued logic (propositional or first-order) into optimal inference rules for a number of related analytic proof systems: many-sided sequent calculus, signed tableaux, many-sided natural deduction, and clause translation calculi for signed resolution. The specification of the logic can be produced by a simple TCL/TK … Continue reading MUltlog 1.13 released

# Teaching Logic Online: Report

Well, my intro to formal logic (Logic I) course is in the can. I think it was a success! I could not have done it without Graham Leach-Krouse's Carnap system, and my excellent team (Husna Farooqui, Sarah Hatcher, Hannah O'Riain, and Dvij Raval). A while back I wrote about the plan to implement specification based … Continue reading Teaching Logic Online: Report

# Many-valued logic in the OLP

We have four new chapters in the OLP. They contain draft material on many-valued logics. The Introduction explains their syntax […]

# Grading for Mastery in Introductory Logic

I've been thinking for a long time about how to do assignments, exams, and grading differently in my intro logic course. Provincial budget cuts mean my enrolment will double to 200 students in the Fall term, and the fact that it will have to be fully online raises additional challenges. So maybe now is a … Continue reading Grading for Mastery in Introductory Logic

# Satisfaction and assignments

When you define satisfaction for quantified formulas, e.g., $$\forall x\, A$$, you have to have a way to make $$x$$ range over all elements of the domain. Here are the common options: A. Tarski-style: use variable assignments $$s\colon V \to D$$ (where $$V$$ is the set of variables and $$D$$ the domain), then define \[\mathfrak{M}, … Continue reading Satisfaction and assignments

# Letter grades in Brightspace/D2L (or other LMS)

So, we're all moving to online courses, and for some of us that means we have to figure out how to switch from scribbling feedback and letter grades on papers, handing them back to students, and turning those letter grades into a course grade at the end. Most of us are using learning management systems … Continue reading Letter grades in Brightspace/D2L (or other LMS)

# Need a logic course, fast?

I wasn't going to put this online until it was done and cleaned up, but given the situation, maybe this can be of help. I just developed and tried out a course on formal logic for a 13-week semester. It has: a free online textbook: forall x: Calgarybeamer slides for lectures (or screencasts)problem sets, which … Continue reading Need a logic course, fast?

# Chalk-and-talk online: whiteboard screencasting (on Linux)

Well, all my logic lectures moved online as of last week. It's been a bit of a scramble, as I'm sure it's been for you as well. I needed to rapidly produce videos of lectures (on logic in my case) I can give with students to watch. I thought I'd quickly share what I'm doing … Continue reading Chalk-and-talk online: whiteboard screencasting (on Linux)

# Adding online exercises with automated grading to any logic course with Carnap

A couple of years ago I posted a roundup of interactive logic courseware with an automatic grading component. The favorite commercial solution is Barwise & Etchemendy's Language, Proof, and Logic textbook that comes with software for doing truth tables, natural deduction proofs, and semantics for propositional and first-order logic, which also automatically grades student's solutions. … Continue reading Adding online exercises with automated grading to any logic course with Carnap

# BibTeX-friendly PDF management with Zotero

For years I've been jealous of colleagues with Macs who apparently all use BibDesk for managing their article PDF collections and BibTeX citations in one nice program. I think I've finally figured out how to do both things on Linux: Zotero, with the Better BibTeX and ZotFile add-ons. Zotero is first of all a citation … Continue reading BibTeX-friendly PDF management with Zotero

# The Emergence of First-Order Logic

The SEP entry on "The Emergence of First-Order Logic" by William Ewald is out today.

# Indian Conference on Logic and its Applications 2019

The Association for Logic in India (ALI) announces the eighth edition of its biennial International Conference on Logic and its Applications (ICLA), to be held at the Indian Institute of Technology Delhi from March 3 to 5, 2019. ICLA is a forum for bringing together researchers from a wide variety of fields in which formal logic … Continue reading Indian Conference on Logic and its Applications 2019

# forall x is going CC BY

The original forall x by P.D. Magnus, as well as Tim Button’s forall x: Cambridge, and the forallx: Calgary remix are now released under a Creative Commons Attribution (rather than the more restrictive Attribution-ShareALike license). The Fall 2018 version also incorporates some of Tim’s revisions for the latest version of forall x: Cambridge. You can find all three on Github: forall x, forall x: Cambridge, and forall x: YYC.

# PhD, Postdoc with Rosalie Iemhoff

Postdoc position in Logic at Utrecht University, the Netherlands. The postdoc is embedded in the research project “Optimal Proofs” funded by the Netherlands Organization for Scientific Research led by Dr. Rosalie Iemhoff, Department of Philosophy and Religious Studies, Utrecht University. The project in mathematical and philosophical logic is concerned with formalization in general and proof … Continue reading PhD, Postdoc with Rosalie Iemhoff

# Proof by legerdemain

Peli Grietzer shared a blog post by David Auerbach on Twitter yesterday containing the following lovely quote about Smullyan and Carnap: I particularly delighted in playing tricks on the philosopher Rudolf Carnap; he was the perfect audience! (Most scientists and mathematicians are; they are so honest themselves 'that they have great difficulty in seeing through … Continue reading Proof by legerdemain