### Boole’s Rings

- Sigma-Prikry II: Iteration Scheme December 4, 2019 Assaf Rinot
- Logic Colloquium Poznan - TBA November 20, 2019 Sandra Müller
- North American Annual Meeting of the ASL - TBA November 19, 2019 Sandra Müller
- Oberseminar mathematische Logik, Bonn - TBA November 18, 2019 Sandra Müller
- Modern class forcing November 13, 2019 Victoria Gitman

### Comments on Boole’s Rings

- Comment on Knaster and friends I: Closed colorings and precalibers by saf November 2, 2019 Comments for Assaf Rinot
- Comment on A relative of the approachability ideal, diamond and non-saturation by On guessing generalized clubs at the successors of regulars | Assaf Rinot October 24, 2019 Comments for Assaf Rinot
- Comment on Solution to my transfinite epistemic logic puzzle, Cheryl’s Rational Gifts by Cheryl’s Rational Gifts: transfinite epistemic logic puzzle challenge! | Joel David Hamkins October 14, 2019 Comments for Joel David Hamkins
- Comment on The propagation of error in classical geometry constructions by Paul Alberti-Strait October 9, 2019 Comments for Joel David Hamkins
- Comment on The modal logic of arithmetic potentialism and the universal algorithm by The $Sigma_1$-definable universal finite sequence | Joel David Hamkins September 30, 2019 Comments for Joel David Hamkins

# Category Archives: Results worth knowing

## An example with Dedekind cuts

In this post, I will briefly describe an example in computability theory that is well known, but not easy to find in the literature. It gives one reason why Dedekind cuts are difficult to work with computationally. Theorem. There is … Continue reading

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## Filter quantifiers

I have been supervising an undergraduate student in an independent study in topology this semester. We have just finished the Stone–Čech compactification, and the semester is ending, so I want to end with an ultrafilter based proof of Hindman’s theorem. … Continue reading

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## Computable roots of computable functions

Here are several interesting results from computable analysis: Theorem 1. If $f$ is a computable function from $\mathbb{R}$ to $\mathbb{R}$ and $\alpha$ is an isolated root of $f$, then $\alpha$ is computable. Corollary 2. If $p(x)$ is a polynomial over … Continue reading