Stuart Presnell
@logopetria.bsky.social
Mathematics, CS, physics, philosophy
Most recently : Teaching logic and philosophy of mathematics in the Philosophy department at the University of Bristol
Most recently : Teaching logic and philosophy of mathematics in the Philosophy department at the University of Bristol
Just hoping this meme format isn't too old and tired by the time we get to make this joke
November 10, 2025 at 2:54 PM
Just hoping this meme format isn't too old and tired by the time we get to make this joke
tag urself, im "left forefoot strike, other feet elevated to rear"
November 8, 2025 at 4:47 PM
tag urself, im "left forefoot strike, other feet elevated to rear"
Visual proofs of inductive arguments are often easier to follow, because by illustrating a few steps of the induction they let the viewer see how to generalise to subsequent steps
October 31, 2025 at 2:59 PM
Visual proofs of inductive arguments are often easier to follow, because by illustrating a few steps of the induction they let the viewer see how to generalise to subsequent steps
This talk of an "inevitable" civil war is utter nonsense — the country has never been more united. Why, just 5 years ago we were governed by a Roundhead and a Cavalier
October 29, 2025 at 12:45 PM
This talk of an "inevitable" civil war is utter nonsense — the country has never been more united. Why, just 5 years ago we were governed by a Roundhead and a Cavalier
Bad luck to those other guys, this was too eas...
October 26, 2025 at 11:16 AM
Bad luck to those other guys, this was too eas...
"Here is one hand, and here is another — and this one's holding a gun"
October 24, 2025 at 7:33 PM
"Here is one hand, and here is another — and this one's holding a gun"
This, but "WWII memorabilia, various"
October 24, 2025 at 5:17 PM
This, but "WWII memorabilia, various"
If you're not getting a link to the Wikipedia page I have a spare you can borrow
October 17, 2025 at 6:29 AM
If you're not getting a link to the Wikipedia page I have a spare you can borrow
It's been quite the week for embarrassing public typos
![A bar of chocolate given out at the 2025 Tory conference. The label says "When Labour negotiates, Britian [sic] loses"](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:rgwjbyx72foshnm75a7z4d2t/bafkreihpmugwp7eei64k7x74yphuddykmiofcjkuy5wrvvkmjk4saqummq@jpeg)
![A poster for "Tron: Ares" with a picture of Jared Leto, who plays the eponymous ares [sic]](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:rgwjbyx72foshnm75a7z4d2t/bafkreif6j53r7ujuvrecowcfdd7jaefbcj6d6ii5rjl2lip77wvixoywtu@jpeg)
October 11, 2025 at 4:44 PM
It's been quite the week for embarrassing public typos
Yes, why won't technologists focus on giving me the things I need to make my life easier:
* a machine to put clothes into the machine that washes my clothes
* a machine to put dishes into the machine that washes my dishes
* a machine to empty the machine that vacuums my floors
* a machine to put clothes into the machine that washes my clothes
* a machine to put dishes into the machine that washes my dishes
* a machine to empty the machine that vacuums my floors
October 11, 2025 at 4:51 AM
Yes, why won't technologists focus on giving me the things I need to make my life easier:
* a machine to put clothes into the machine that washes my clothes
* a machine to put dishes into the machine that washes my dishes
* a machine to empty the machine that vacuums my floors
* a machine to put clothes into the machine that washes my clothes
* a machine to put dishes into the machine that washes my dishes
* a machine to empty the machine that vacuums my floors
I've drawn a slightly straightened-up version of the first unknotted stage of this sequence. This should be easier to re-draw in TikZ, and then work forwards and backwards to re-create the other diagrams in the two sequences
October 9, 2025 at 2:34 PM
I've drawn a slightly straightened-up version of the first unknotted stage of this sequence. This should be easier to re-draw in TikZ, and then work forwards and backwards to re-create the other diagrams in the two sequences
Ah, I think I see what I was missing. Rather than taking the connected sum in the most obvious way (joining AC and BD), we're first dragging one arc behind the rest of the knot (as shown here). Then taking the connected sum at the position indicated joins AD and BC
October 9, 2025 at 9:57 AM
Ah, I think I see what I was missing. Rather than taking the connected sum in the most obvious way (joining AC and BD), we're first dragging one arc behind the rest of the knot (as shown here). Then taking the connected sum at the position indicated joins AD and BC
Sorry if I'm being stupid here but I'm having difficulty following the sequence of diagrams — I'm failing at the first move!
You start with the connected sum of the (2,7) torus knot and its mirror image, joined by AC and BD. But after the first move we now have AD and BC. What's happened here?
You start with the connected sum of the (2,7) torus knot and its mirror image, joined by AC and BD. But after the first move we now have AD and BC. What's happened here?
October 9, 2025 at 6:39 AM
Sorry if I'm being stupid here but I'm having difficulty following the sequence of diagrams — I'm failing at the first move!
You start with the connected sum of the (2,7) torus knot and its mirror image, joined by AC and BD. But after the first move we now have AD and BC. What's happened here?
You start with the connected sum of the (2,7) torus knot and its mirror image, joined by AC and BD. But after the first move we now have AD and BC. What's happened here?
Using GitHub to keep track of changes while you're working is really useful — for example, it's saved me on countless occasions from Find-and-Replace operations gone awry
But there are downsides — like when you take a "5 minute break" and come back to find this message staring reproachfully at you
But there are downsides — like when you take a "5 minute break" and come back to find this message staring reproachfully at you
October 7, 2025 at 10:01 AM
Using GitHub to keep track of changes while you're working is really useful — for example, it's saved me on countless occasions from Find-and-Replace operations gone awry
But there are downsides — like when you take a "5 minute break" and come back to find this message staring reproachfully at you
But there are downsides — like when you take a "5 minute break" and come back to find this message staring reproachfully at you
We've really got to come up with separate names for the two different things people call "impostor syndrome", because for some of us posts like this really aren't helping
October 6, 2025 at 10:22 PM
We've really got to come up with separate names for the two different things people call "impostor syndrome", because for some of us posts like this really aren't helping
September 28, 2025 at 8:52 AM
Re-upping this feature request, because sometimes you've *really* got to read the quoted post before reading the reply
September 27, 2025 at 5:28 AM
Re-upping this feature request, because sometimes you've *really* got to read the quoted post before reading the reply
Not sure how I originally got this mixed up, but I've just learned that playwright Peter Shaffer, author of Amadeus, and playwright Patrick Marber, who played Peter O'Hanraha-hanrahan in The Day Today, are two different people
September 25, 2025 at 8:29 AM
Not sure how I originally got this mixed up, but I've just learned that playwright Peter Shaffer, author of Amadeus, and playwright Patrick Marber, who played Peter O'Hanraha-hanrahan in The Day Today, are two different people
![Picture of Charles Babbage with an edited quote:
On two occasions I have been asked, 'Pray, Mr. Babbage, if you [train the machine to guess instead of saying "I don’t know"] will the right answers come out?' I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:rgwjbyx72foshnm75a7z4d2t/bafkreicvn3fgll5coxvw76bdnghgbddmhpooum5psy2ne2gp4v4z45q664@jpeg)
This absurd episode of flag mania sweeping the nation might have been quashed by suitable levels of embarrassment if the BBC had just managed to keep showing repeats of The Goodies
September 8, 2025 at 8:39 AM
This absurd episode of flag mania sweeping the nation might have been quashed by suitable levels of embarrassment if the BBC had just managed to keep showing repeats of The Goodies