### Boole’s Rings

- The modal logic of potentialism, ILLC Amsterdam, May 2019 April 15, 2019 Joel David Hamkins
- Is there just one mathematical universe? DRIFT, Amsterdam, May 2019 April 14, 2019 Joel David Hamkins
- Philosophy of Mathematics, graduate lecture seminar, Oxford, Trinity term 2019 April 11, 2019 Joel David Hamkins
- Kelley-Morse set theory does not prove the class Fodor principle April 9, 2019 Joel David Hamkins
- A Rodgers-Saxl type conjecture for characters April 5, 2019 Nick Gill

### Comments on Boole’s Rings

- Comment on Is there just one mathematical universe? DRIFT, Amsterdam, May 2019 by Hendrik Boom April 14, 2019 Comments for Joel David Hamkins
- Comment on Kelley-Morse set theory does not prove the class Fodor Principle, CUNY Set Theory Seminar, March, 2019 by Joel David Hamkins March 22, 2019 Comments for Joel David Hamkins
- Comment on An inconsistent form of club guessing by saf March 13, 2019 Comments for Assaf Rinot
- Comment on An inconsistent form of club guessing by Ari B. March 10, 2019 Comments for Assaf Rinot
- Comment on Draw an infinite chessboard in perspective, using straightedge only by Joel David Hamkins February 25, 2019 Comments for Joel David Hamkins

# Category Archives: Research

## Reverse Mathematics of Matroids

This post is about the paper Reverse Mathematics of Matroids by Jeff Hirst and me. We look at basis theorems for countable vector spaces, countable graphs, and countable enumerated matroids. These three kinds of structures turn out to be extremely … Continue reading

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## Talk on the existence of connected components of graphs

This week I am attending a seminar at Dagstuhl on Measuring the Complexity of Computational Content: Weihrauch Reducibility and Reverse Analysis. This post has slides from my talk and some blog-only remarks to expand on them.

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## Talk on Reverse Mathematics and the Modal Logic of Reverse Mathematics

This is a transcription of notes from a talk I gave on November 1, 2013 to the interdisciplinary logic seminar at the University of Connecticut. I gave a general introduction to Reverse Mathematics and then spoke about my work with … Continue reading

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## Internal combinatorics and uniform reducibility

This post is a set of notes from a talk I gave on December 5th for the discrete mathematics seminar at Marshall University. I want to argue that logical analysis can reveal the “internal combinatorics” of theorems, using some recent … Continue reading

Posted in Musings, Research, Talks
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## An incompleteness theorem for β_{n} models

My first paper was “An incompleteness theorem for $\beta_n$ models” with Stephen Simpson [1]. It’s a short paper, but the idea is very pretty. We know that the incompleteness theorem implies there are strange models of arithmetic, but these models … Continue reading

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## The logic of Reverse Mathematics

This post is about a research idea I have been thinking about which is quite different from my usual research. It’s an example of a project with an “old fashioned” feel to it, as if it could have been studied … Continue reading