### Boole’s Rings

- Generalizations of Laver tables Abridged posted! March 21, 2017 Joseph Van Name
- Stationary preserving permutations are the identity on a club March 20, 2017 Asaf Karagila
- Ternary Laver table calculator (now with a local and a global calculator) March 16, 2017 Joseph Van Name
- overlay journals March 16, 2017 Peter Krautzberger
- Computable processes which produce any desired output in the right nonstandard model March 15, 2017 Victoria Gitman

### Comments on Boole’s Rings

- Comment on All triangles are isosceles by Joel David Hamkins March 13, 2017 Comments for Joel David Hamkins
- Comment on All triangles are isosceles by Spring Beauty (@SpringBeautyDJ) March 12, 2017 Comments for Joel David Hamkins
- Comment on All triangles are isosceles by Joel David Hamkins March 11, 2017 Comments for Joel David Hamkins
- Comment on Buckets of fish! by Buckets of Fish and Defeating Hydras | Mike's Math Page March 11, 2017 Comments for Joel David Hamkins
- Comment on All triangles are isosceles by Spring Beauty (@SpringBeautyDJ) March 11, 2017 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