### Boole’s Rings

- A POW problem that can incentivize the energy efficient CNOT computer. November 18, 2017 Joseph Van Name
- A remark on Schimmerling’s question November 14, 2017 Assaf Rinot
- Classification of countable models of PA and ZFC November 14, 2017 Samuel Coskey
- A universal finite set, CUNY Logic Workshop, November 2017 November 11, 2017 Joel David Hamkins
- Security report for R5, the POW problem for Nebula. November 9, 2017 Joseph Van Name

### Comments on Boole’s Rings

- Comment on Trust me, I’m a doctor! by Stefan Mesken November 15, 2017 Comments for Asaf Karagila
- Comment on A universal finite set, CUNY Logic Workshop, November 2017 by Mohammad November 12, 2017 Comments for Joel David Hamkins
- Comment on Famous quotations in their original first-order language by Joel David Hamkins November 10, 2017 Comments for Joel David Hamkins
- Comment on Famous quotations in their original first-order language by Dee November 10, 2017 Comments for Joel David Hamkins
- Comment on The eightfold way by saf November 6, 2017 Comments for Assaf Rinot

# 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