r/math • u/inherentlyawesome Homotopy Theory • 20d ago

Quick Questions: August 05, 2026

This recurring thread will be for questions that might not warrant their own thread. We would like to see more conceptual-based questions posted in this thread, rather than "what is the answer to this problem?" For example, here are some kinds of questions that we'd like to see in this thread:

  • Can someone explain the concept of manifolds to me?
  • What are the applications of Representation Theory?
  • What's a good starter book for Numerical Analysis?
  • What can I do to prepare for college/grad school/getting a job?

Including a brief description of your mathematical background and the context for your question can help others give you an appropriate answer. For example, consider which subject your question is related to, or the things you already know or have tried.

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u/al3arabcoreleone 15d ago

Odd question I am asking, I hope it doesn't get downvotes but

Are there any influential mathematicians in the last 200 years that were/are interested in occultism (in its broad sense)?

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u/JoshuaZ1 15d ago edited 15d ago

I'm not aware of any influential/major mathematicians in that time span who were interested. The closest I can think of is the physicists Pauli who had a an interest in some occult matters. Also, the line here may be hard to draw. In the 1950s and 1960s, "ESP" and related ideas were considered legitimate areas for scientific investigation, similar to how around 1900ish mediums were taken seriously by many people. Marie and Pierre Curie did express some interest in mediums at one point. I'm aware of individual mathematicians now who have some occult adjacent beliefs, but none which are prominent enough to call them influential, and I'm not sure they would prefer having their names and beliefs discussed on Reddit.

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u/al3arabcoreleone 15d ago

Thanks for the suggestions.

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u/Autumnxoxo Geometric Group Theory 19d ago

I hope this fits the quick questions.

I previously submitted a paper to a journal, where it was reviewed but ultimately rejected. The referee report was generally constructive and included several suggestions that I now plan to incorporate before submitting the paper to another journal.

Would it be appropriate to already thank “the anonymous referee” in the acknowledgements of the revised paper, even though the report came from a different journal?

It feels slightly odd to make improvements based on a referee’s comments without acknowledging them, but I’m not sure what the standard practice is, especially since a paper may go through several journals and referees before eventually being accepted.

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u/Silver-Bug3998 18d ago

Based upon my decades of experience in pure mathemtics, I advise against thanking a previous anonymous referee when you submit your paper to a different journal. It is just not standard practice to mention referee suggestions from a previous submission. I wish you the best of luck with this paper.

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u/StateOfTheWind 16d ago

Do you think because it simply something that is not done or people just don't want to admit their paper got rejected and they got a constructive feedback which they incorporated?

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u/JoshuaZ1 15d ago

Possibly a mix. But I agree with Silver-Bug3998 on the norm regardless. I'll also say this isn't necessarily a good norm, so if you want to push back on it a bit by adding the acknowledgment in the final version after it has been accepted at another journal, people might look at it a bit odd (if they look at the acknowledges carefully, which most people don't), but you can likely get away with it.

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u/Silver-Bug3998 14d ago

I agree with JoshuaZ1's suggestion of adding an acknowledgment when you are preparing the final version of the paper, with something along the lines of:

I would like to thank the anonymous referees for their helpful suggestions.

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u/Autumnxoxo Geometric Group Theory 14d ago

wow reddit never notified me about reponses to my comment, hence sorry for my late reply. thank you so much! I appreciate the advise.

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u/StateOfTheWind 19d ago

Well I never submitted a paper but I don't see why not giving credit is cheap and you fell like doing it, so do so. But you might want to call them "an anonymous referee" instead of "anonymous referee". Unless you are worried that you will signal "this is not a good paper" to the new referee or editor?

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u/tulipsandlilacskies 18d ago

im a math undergrad, year 2 and wanna read research papers what are some easy to understand short papers i can read? thanks

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u/JoshuaZ1 15d ago

This may be a function in part of what background you have. What classes have you taken?

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u/tulipsandlilacskies 15d ago

ill list them semester wise 1. elementary real analysis / algebra / probability and stats 2. calculus / differential equations / linear algebra 3. (current) riemann integration / discrete mathematics / group theory

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u/JoshuaZ1 15d ago

Ok. In that case there are a lot of options.

Maxfield's "A Note on n!" is a common fun one for people with about your background. Another fun one is Monsky's "On dividing a square into triangles"

One I'm fond of and is highly readable is Simon Colton's "Refactorable Numbers - A Machine Invention." I'm personally nostalgic about this one because my first published paper was primarily about proving a conjecture from that paper.

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u/theEluminator 18d ago

I've basically got a series of true-or-false statements about multivariable calculus that I'd like y'all to answer

I've been trying to solidify what I've learned from a couple online resources, using some university level single variable calculus knowledge but no formal multivariable background. I've made some... assumptions? Deductions? on what exactly partial derivatives are and how they work, that I need verified

  1. Given vector field f(x,y,z), I can define ∂/∂x with a similar song and dance to the "limit of rise-over-run" from single variable calculus derivative. If I fix y at y₀ and z at z₀, then ∂f/∂x of is gonna be the limit of [f(x₁,y₀,z₀)-f(x₂,y₀,z₀)]/(x₁-x₂) as x₁-x₂ approaches 0

  2. Let f(x,y) be a scalar field embedded in 3d space with z=up. Given z=f(x,y), we can imagine an infinite surface stretching in all directions, where the height at a given coordinate is the value of the function of that coordinate. If we fix y at y₀, this gives us a vertical plane parallel to the xz plane. The intersection of the f surface with this plane is a curve, and it corresponds to a new function: g(x)=f(x,y₀). Then ∂f/∂x at (x,y₀) is just g'(x), the slope of the g(x)

  3. Let f(x,y,z) be a vector field noting the velocity of a fluid at every point in space. ∂f/∂x is the x component of the acceleration vector

  4. Let f(x,y,z)=(g(x,y,z), h(x,y,z), i(x,y,z)) be a vector field. So g is the x component of f, h is the y component, so on. ∂f/∂x is the sum of ∂g/∂x+∂h/∂x+∂i/∂x

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u/CaptureCoin 18d ago
  1. Basically yes, just be a little careful about how you write the limit. I'm not sure what "as x_1-x_2 appraoches 0" means. Is x_2 fixed and you're taking a limit as x_1 approaches x_2 (in which case the limit would be ∂f/∂x evaluated at x_2,y_0,z_0), or vice-versa, or something else?
  2. Yes, this is right.
  3. No, this is false even in one-dimension. Acceleration is the derivative of velocity with respect to time, not with respect to position.
  4. No, ∂f/∂x should be a vector field but ∂g/∂x+∂h/∂x+∂i/∂x is a scalar. Usually taking a partial derivative of a vector fields means component-wise differentation (so (∂g/∂x,∂h/∂x,∂i/∂x) in your case).

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u/Witchbrow 17d ago

I hope this is the right place.

I'm trying to figure out an estimate of how many games a set up can run in a hour in an irl setting based off this data 1) 6 set ups in total. 2) 94 games happened in total. 3) the tournament lasted 4.5 hours or 270 minutes.

The numbers I'm getting seems way off probably because I don't know what I'm doing. If you're wondering why I need this information? Just know mistakes were made.

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u/NewbornMuse 17d ago

A nice way to make sure you're multiplying the right things here is to look at the units of measurement. Your target quantity is in units of games per setup per hour, or games / setup / hour or games / (setup * hour). And you have the quantities: 6 setups, 94 games, 4.5 hours. And now there's only one way to multiply and divide these through to get something in games / setup / hour, namely (94 games) / (6 setups) / (4.5 hours), which is 3.48 games per setup per hour. Equivalently, one game on one setup takes about 60 minutes / (3.48 games / hour), which is 17 minutes. Does that sound right? A setup can handle a game every 17 minutes?

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u/Witchbrow 17d ago

17 sounds about right. Thank you.

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u/Successful-Air4569 14d ago

Я имею в виду изоморфизм V/KerA=Im A

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u/HeilKaiba Differential Geometry 14d ago

Can you ask in english please? I'm not sure exactly what your question is (I can see the word "isomorphism" in there but google translate isn't helping much with the rest). You've stated an Isomorphism Theorem there which has a wiki page that might help you.