Rupadarshi Ray
@rupadarshiray.bsky.social
Mathematics. obsidian.md.
Reposted by Rupadarshi Ray
"A good mathematical joke is better, and better mathematics, than a dozen mediocre papers." [J E Littlewood]
November 4, 2025 at 4:15 PM
"A good mathematical joke is better, and better mathematics, than a dozen mediocre papers." [J E Littlewood]
Degree of symmetry of Riemannian manifolds www2.math.upenn.edu/~wziller/mat...
October 29, 2025 at 6:16 PM
Degree of symmetry of Riemannian manifolds www2.math.upenn.edu/~wziller/mat...
Reposted by Rupadarshi Ray
I should embroider this and hang it in my office.
👍👏❤️😘🥰😍
👍👏❤️😘🥰😍
But who looks at h-index in math anyway?
October 25, 2025 at 5:00 PM
I should embroider this and hang it in my office.
👍👏❤️😘🥰😍
👍👏❤️😘🥰😍
Reposted by Rupadarshi Ray
i love when the textbook says "give a careful proof of" instead of "prove." oh so you think my proofs are normally careless. because i'm a bad mathematician. you hate me. you want me to hurt myself
October 24, 2025 at 5:23 AM
i love when the textbook says "give a careful proof of" instead of "prove." oh so you think my proofs are normally careless. because i'm a bad mathematician. you hate me. you want me to hurt myself
Reposted by Rupadarshi Ray
i just finished switching from onenote to obsidian before i saw this post. it was really easy to import everything. i got sick of microsoft having access to all my work. You can also import google keep!
obsidian.md
obsidian.md
Obsidian - Sharpen your thinking
The free and flexible app for your private thoughts.
obsidian.md
August 22, 2025 at 6:52 PM
i just finished switching from onenote to obsidian before i saw this post. it was really easy to import everything. i got sick of microsoft having access to all my work. You can also import google keep!
obsidian.md
obsidian.md
Reposted by Rupadarshi Ray
Day 1: Hopfield Network (doesn't look very elegant but that's fine ig)
June 23, 2025 at 6:13 PM
Day 1: Hopfield Network (doesn't look very elegant but that's fine ig)
Reposted by Rupadarshi Ray
Cauchy problem for inviscid Burgers' equation is not "solvable" (globally) for many initial conditions...but we can depict the graph of the function that "could have been the solution"... (and the characteristic surface of course)
May 29, 2025 at 8:31 PM
Cauchy problem for inviscid Burgers' equation is not "solvable" (globally) for many initial conditions...but we can depict the graph of the function that "could have been the solution"... (and the characteristic surface of course)
A sympy script in #obsidianmd. Powers of Arnold cat map matrix gives you FIbonacci coefficients and thus they grow exponentially...
May 29, 2025 at 12:50 PM
A sympy script in #obsidianmd. Powers of Arnold cat map matrix gives you FIbonacci coefficients and thus they grow exponentially...
Red: preimage of unit disk under a complex polynomial, or |p(z)|< 1
Violet, black: Curves defined by real and complex parts of p = 0 resp.
Violet, black: Curves defined by real and complex parts of p = 0 resp.
May 29, 2025 at 12:35 PM
Red: preimage of unit disk under a complex polynomial, or |p(z)|< 1
Violet, black: Curves defined by real and complex parts of p = 0 resp.
Violet, black: Curves defined by real and complex parts of p = 0 resp.
Was editing the roadmap rupadarshiray.github.io/academia/inc...
Inculcation
Driven by infinite enthusiasm § This list was made with materials mostly found on the internet, to reduce repetition from my side. All opinions are strictly mine.
rupadarshiray.github.io
May 29, 2025 at 12:29 PM
Was editing the roadmap rupadarshiray.github.io/academia/inc...
Reposted by Rupadarshi Ray
Obsidian 1.8.0 (early access) is now available to Catalyst members for desktop and mobile!
- New web viewer plugin
- New command to download local images
- Improvements for iCloud on mobile
Release notes:
obsidian.md/changelog/20...
- New web viewer plugin
- New command to download local images
- Improvements for iCloud on mobile
Release notes:
obsidian.md/changelog/20...
Obsidian 1.8.0 Desktop (Early access)
New - Web viewer, a new core plugin, lets you open external links within Obsidian. This simplifies reading linked content without leaving the app and makes mult...
obsidian.md
December 18, 2024 at 9:02 PM
Obsidian 1.8.0 (early access) is now available to Catalyst members for desktop and mobile!
- New web viewer plugin
- New command to download local images
- Improvements for iCloud on mobile
Release notes:
obsidian.md/changelog/20...
- New web viewer plugin
- New command to download local images
- Improvements for iCloud on mobile
Release notes:
obsidian.md/changelog/20...
Reposted by Rupadarshi Ray
Rupadarshi Ray @rupadarshiray.bsky.social has the answer to my question on why we use the letter O for rings of holomorphic functions (and later structure sheaves of algebraic varieties and schemes)...
The letter 'O' seems mathoverflow.net/questions/92... to be coming from an old name for "rings" themselves
Etymology of the O-notation for algebras of holomorphic functions
The notation $O(X)$ seems to be a quite standard notation for the algebra of all holomorphic functions on some connected domain in $\mathbb{C}^n$ (or a complex manifold). I would like to know where...
mathoverflow.net
December 18, 2024 at 4:59 PM
Rupadarshi Ray @rupadarshiray.bsky.social has the answer to my question on why we use the letter O for rings of holomorphic functions (and later structure sheaves of algebraic varieties and schemes)...
Reposted by Rupadarshi Ray
| @vickythesillay.bsky.social |
"You get this Calabi–Yau manifold. It's a bit dusty, but it's a nice decoration for any higher dimensional home."
"You get this Calabi–Yau manifold. It's a bit dusty, but it's a nice decoration for any higher dimensional home."
a computer generated image of a purple and green swirl against a black background
ALT: a computer generated image of a purple and green swirl against a black background
media.tenor.com
December 8, 2024 at 11:27 PM
| @vickythesillay.bsky.social |
"You get this Calabi–Yau manifold. It's a bit dusty, but it's a nice decoration for any higher dimensional home."
"You get this Calabi–Yau manifold. It's a bit dusty, but it's a nice decoration for any higher dimensional home."
Reposted by Rupadarshi Ray
"oh no differential geometry is really quite complicated"
Differential geometry: "Leibniz rule go brrrr"
Differential geometry: "Leibniz rule go brrrr"
December 11, 2024 at 1:01 PM
"oh no differential geometry is really quite complicated"
Differential geometry: "Leibniz rule go brrrr"
Differential geometry: "Leibniz rule go brrrr"
Reposted by Rupadarshi Ray
Got into a big fight with a colleague about whether to use a variety with a singularity or lift it to a manifold, but in the end we managed to smooth it out
September 18, 2023 at 1:42 PM
Got into a big fight with a colleague about whether to use a variety with a singularity or lift it to a manifold, but in the end we managed to smooth it out
Reposted by Rupadarshi Ray
If you take a surface of codimension 1 in a smooth manifold that's topologically an n-sphere, you can accumulate a path through the rotation group near it while rigidly rotating the interior and make the diffeomorphism group do the belt trick; expect SU(2) (not SO(3)) reps in gravity.
What are you rotating in your mind right now?
September 20, 2023 at 12:11 AM
If you take a surface of codimension 1 in a smooth manifold that's topologically an n-sphere, you can accumulate a path through the rotation group near it while rigidly rotating the interior and make the diffeomorphism group do the belt trick; expect SU(2) (not SO(3)) reps in gravity.
Strictly speaking classical mechanical phase spaces are cotangent spaces T*M only. So even though S^2 has symplectic forms, it can never be such a phase space as its not cotangent bundle of any 1-manifold (R, S^1 both have trivial tangent bundles).
Okay so a symplectic manifold is a generalization of phase space, and there can’t be a symplectic form on S^2n if n>2 because the cohomology classes don’t work out, so does that mean that you just can’t have phase spaces that look like a sphere?
December 17, 2024 at 7:59 PM
Strictly speaking classical mechanical phase spaces are cotangent spaces T*M only. So even though S^2 has symplectic forms, it can never be such a phase space as its not cotangent bundle of any 1-manifold (R, S^1 both have trivial tangent bundles).
woops 😛
December 17, 2024 at 7:55 PM
woops 😛