Bjørn Kjos-Hanssen 's Avatar

Bjørn Kjos-Hanssen

@kjoshanssen

Math professor

180
Followers
14
Following
18
Posts
12.08.2023
Joined
Posts Following

Latest posts by Bjørn Kjos-Hanssen @kjoshanssen

How about a sentence?
A bi cat, dark eagle friend, glanced homeward illegally.

04.02.2026 18:28 👍 0 🔁 0 💬 1 📌 0

I could come up with all kinds of strange contracts and then claim that "in some sense this is 8% interest!"

A particularly egregious example is "annual rest" whereby payments made monthly throughout the year only start to earn interest at the end of the year 🙄

2 / 2

13.12.2025 19:02 👍 0 🔁 0 💬 0 📌 0

I used to think that nominal interest was a great way to introduce the number e. But after teaching a class on this stuff, now I feel like nominal interest is mostly just a socially constructed way to say the interest rate is say 8% when it's really not!
🧵
1/2

13.12.2025 19:02 👍 1 🔁 0 💬 1 📌 0

If f and g are automorphisms of a partial order L, and a ≤ f(b) and b ≤ g(a) ... then is there an automorphism sending a to b?
(I know the answer but am curious what arguments/examples others may have. Caution: it's too hard for ChatGPT!)

18.04.2025 01:55 👍 0 🔁 0 💬 0 📌 0

I've always heard it referred to as simply "product".

09.02.2025 21:04 👍 0 🔁 0 💬 1 📌 0

If you don't know me, I'm 9, where m=3 and b=2

10.12.2024 05:27 👍 0 🔁 0 💬 0 📌 0
Video thumbnail

Ask not what this is --- ask "what is this knot?"

30.11.2024 18:51 👍 0 🔁 0 💬 0 📌 0
Video thumbnail

An "attractive" red cube in the middle of this polymer.

29.11.2024 23:30 👍 1 🔁 0 💬 0 📌 0
Video thumbnail

An example of the nonmonotonicity of optimal protein folding in the hydrophobic-polar model!

29.11.2024 00:36 👍 1 🔁 0 💬 0 📌 0
Video thumbnail

Here's an example of my online game Labbyfold. Fold proteins into their optimal configuration! math.hawaii.edu/~bjoern/?she...

25.11.2024 23:45 👍 0 🔁 0 💬 0 📌 0

Picture... or it didn't happen? 🙂

09.11.2024 07:35 👍 0 🔁 0 💬 1 📌 0
Post image

I forget the proper terminology! But the DFA is shown below. The alphabet is {0,1}. Reading 000 you go in a 3-cycle from q₀ to q₀. Given this you can fill in all edge labels. The big diagram above indicates that states (q₀,q₁,q₂) go to (q₁,q₂,q₀) when reading a 0, by having an arrow from 012 to 120.

09.11.2024 06:55 👍 0 🔁 0 💬 1 📌 0
Post image

Thanks --- here's a monoid from my book!

09.11.2024 06:09 👍 0 🔁 0 💬 1 📌 0
Post image

🍿

17.11.2023 23:28 👍 2 🔁 0 💬 0 📌 0

I kept hearing about "logical depth" so I gave in and wrote a paper about it.
math.hawaii.edu/~bjoern/logical-depth-knapsack.pdf

02.10.2023 04:23 👍 1 🔁 0 💬 0 📌 0

UNIQUE SUBSET SUM is coNP-hard. Reference?

01.09.2023 04:01 👍 7 🔁 0 💬 0 📌 0

They have different types so they can't be compared as = or not =.

30.08.2023 19:23 👍 0 🔁 0 💬 0 📌 0

No, sorry.

23.08.2023 07:23 👍 0 🔁 0 💬 0 📌 0