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Shaun Isherwood

@shaunlovesmaths

I'm a PhD student at the University of Aberdeen studying group theory, an area of mathematics concerning symmetry. I have schizophrenia. I'm wrapping up my research project.

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28.12.2023
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Latest posts by Shaun Isherwood @shaunlovesmaths

She has social housing now!

05.03.2026 12:54 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

There is no set of all sets.

13.02.2026 00:19 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Someone I know has been homeless for a couple of nights. She can't go to her family; they're abusive.

She and her boyfriend have 6 months' rent saved. They can't find a guarantor.

It's a sad situation. I wish there was something I could do.

(This has been anonymised for safety reasons.)

12.02.2026 23:34 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

There are mathematical equations of warfare. For example, Lanchester's laws.

04.02.2026 13:53 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Sex and Sensibility
Sex and Sensibility YouTube video by Forrest Valkai

Finished! :)

youtu.be/nVQplt7Chos?...

01.02.2026 21:03 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

For any natural n, n⁷=n³ (mod 40).

01.02.2026 19:35 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Biology vs. Gender Ideology: The Science Behind the Debate
Biology vs. Gender Ideology: The Science Behind the Debate YouTube video by Skeptic

Hi @forrestvalkai.bsky.social,

May I have your opinion on this, please? I guess you've seen these arguments before.

The video is just under 19 minutes long. It's a lot. Your time is valuable, and I respect that.

Meanwhile, I'll watch your Sex & Sensibility video again

youtu.be/nU-rYQB_OjE?...

01.02.2026 19:14 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

If p=3 (mod 4), then xΒ²=-1 (mod p) has no solutions.

19.01.2026 00:03 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Preview
Gay Speed Dating Problem Here's an interesting problem that I came up with the other night. With straight speed dating, (assuming the number of men and women are equal) the number of iterations that need to be made before...

math.stackexchange.com/q/55439/104041

18.01.2026 14:27 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

The sequence

1+z+2z²+3z³+5z⁴+8z⁡+13z⁢+...

is equal to 1/(1-(z+zΒ²)), where the coefficients are Fibonacci numbers.

18.01.2026 14:09 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Let k and n be natural numbers. Then the nth Fibonacci number divides the (kn)th Fibonacci number.

17.01.2026 21:43 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

this is genuinely incredible

15.01.2026 13:31 πŸ‘ 13421 πŸ” 5148 πŸ’¬ 91 πŸ“Œ 91

I just explained to a guy on the internet that an event with probability zero can still happen. He had a tantrum about it then blocked me.

It was funny!

16.01.2026 11:18 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

(I've already emailed my supervisor about this today, so there's no need to suggest I do that.)

11.01.2026 23:11 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

I keep feeling as if I'll fail my PhD. This is normal, I know, but that doesn't make me feel any better.

My dissertation might well be very short. I doubt I can produce enough mathematics for the degree.

Mileage varies for doctorates. They're each unique. This fact is also of no comfort.

11.01.2026 23:08 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

The following is logically valid for any predicate P:

βˆƒx(Pxβ†’βˆ€yPx).

08.01.2026 18:44 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Given integers a, b, c with a+b+c=0, we have that 32(a⁴+b⁴+c⁴) is square.

06.01.2026 18:03 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

I spent three hours typing up msthematical notes in LaTeX. The result? One side of A4.

Fuck my life.

06.01.2026 17:56 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

I ❀️ Maths!

30.12.2025 00:34 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

@theardenhart.bsky.social :)

30.12.2025 00:31 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

The Ξ©th root of Ο‰ is ∞, where Ξ© is the "gap at the end of the surreal number line," Ο‰ is a specific infinite surreal number, and ∞ is the gap between finite and infinite surreal numbers.

30.12.2025 00:30 πŸ‘ 0 πŸ” 0 πŸ’¬ 2 πŸ“Œ 0

Is this modulo one?

23.12.2025 13:51 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Here's a proof using complex numbers:

n⁴+4
=(nΒ²+2i)(nΒ²-2i)
=(n+1+i)(n-1-i)(n+1-i)(n-1+i)
=(n+1+i)(n+1-i)(n-1-i)(n-1+i)
=((n+1)Β²+1)((n-1)Β²+1),

where the last equality is by a difference of squares.

Note that each factor is greater than 1 when n>1. Q.E.D.

14.12.2025 12:29 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

@katyptcg.bsky.social

For natural n>1, n⁴+4 is never prime.

13.12.2025 19:48 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

@forrestvalkai.bsky.social

How well, in your opinion, does Conway's, "The Game of Life" describe life in general?

The game is "Turing complete"; I know that much. That means it can simulate any computer.

By the way, there is a free simulation of it via the Google Play store, called "Golly".

03.12.2025 14:51 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

@forrestvalkai.bsky.social

As a lay person in biology, I summarise the main thesis of Dawkins', "The Selfish Gene" to be: morality is game theory acting on genes, with memes (in the original sense of the word) taking over evolved instincts.

Would that be accurate?

Do his ideas still hold today?

28.11.2025 15:32 πŸ‘ 3 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Post image

#mathematics #math #analysis
Source:https://buff.ly/5Qhr7NT

28.11.2025 14:02 πŸ‘ 1 πŸ” 1 πŸ’¬ 0 πŸ“Œ 0

@forrestvalkai.bsky.social

There are mathematical systems that model logics in which at least one of the laws of logic (i.e., identity, noncontradiction, and excluded middle) does not hold.

Do you think pointing to them would get past presuppositionalists' insistence we justify "faith" in logic?

13.11.2025 14:10 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Post image

Dictators don’t like mathβ€”because math insists on reality.

We’re still trying to work out how this math maths. Is he suggesting people are crossing illegally out of the US into Mexico and Canada? Math exposes the lie, but when reality is inconvenient, the authoritarian will simply demand a new one.

03.11.2025 16:56 πŸ‘ 1685 πŸ” 441 πŸ’¬ 128 πŸ“Œ 43
Preview
Donate to Final Stretch of PhD., organized by Shaun Isherwood Hello, I'm Shaun Isherwood, a PhD student of mathematics at The University of Aberdeen (UK).… Shaun Isherwood needs your support for Final Stretch of PhD.

Here's a GoFundMe for my PhD:

gofund.me/427845051

24.10.2025 11:36 πŸ‘ 2 πŸ” 1 πŸ’¬ 0 πŸ“Œ 0