### Boole’s Rings

- Brace(s) yourself April 19, 2018 Peter Krautzberger
- Infinite Sudoku and the Sudoku game April 17, 2018 Joel David Hamkins
- Conjugacy for homogeneous ordered graphs April 12, 2018 Samuel Coskey
- Kameryn J. Williams, PhD 2018, CUNY Graduate Center April 8, 2018 Joel David Hamkins
- Open Problems! April 8, 2018 Asaf Karagila

### Comments on Boole’s Rings

- Comment on Math for nine-year-olds: fold, punch and cut for symmetry! by Joel David Hamkins April 19, 2018 Comments for Joel David Hamkins
- Comment on Math for nine-year-olds: fold, punch and cut for symmetry! by Jen April 19, 2018 Comments for Joel David Hamkins
- Comment on Infinite Sudoku and the Sudoku game by Joel David Hamkins April 17, 2018 Comments for Joel David Hamkins
- Comment on Infinite Sudoku and the Sudoku game by Joel David Hamkins April 17, 2018 Comments for Joel David Hamkins
- Comment on Infinite Sudoku and the Sudoku game by Infinite Sudoku and the Sudoku game – Nevin Manimala’s Blog April 17, 2018 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