Hi guys! You can leave messages for me here.

My previous messageboard has too many comments and images, which cause it to load slowly. If you have a previous conversation please continue it there instead of starting a new thread here.

I will be editing and deleting comments to help keep this loading fast. E.g. Once images are irrelevant, they will simply be displayed as a hyperlink, instead of requiring everyone to download the picture. Irrelevant comments will be deleted.

Please keep conversations separate, IE start a new thread for different comments. This will allow me to easily keep track of live discussions.

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TopNewestBug report: Lately now I can't edit recent comments or solutions. When I try to click "Edit" out of a choice between "Edit" and "Delete", it vanishes and won't activate. This is new. – Michael Mendrin · 2 months, 1 week ago

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(Really sorry for the inconvenience. I know what a pain this is. It took us a while to find the root of the bug.) – Calvin Lin Staff · 1 day, 4 hours ago

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Edit: This time it works, when just an hour ago it wasn't. Let me go try this elsewhere.

Edit 2: Yes, it now works elsewhere, where heretofore I couldn't edit. It's strange how this keeps cropping up. – Michael Mendrin · 1 day, 3 hours ago

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As far as we can see, it doesn't affect subsequent comments. – Calvin Lin Staff · 2 months, 1 week ago

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@Guillermo Templado To be clear, your solution was correct under the condition of Lebesgue integration. For a variety of reasons, Lebesgue integration should be the "standard framework" of performing calculus, as that allows us to get around Riemannian integration issues like the one that I pointed out. (It's just that the slip-shod Riemannian integration is easier to explain to high school students, and they completely gloss over the technical details by making various assumptions like continuous, absolutely continuous, bounded, etc.)

Do you mind if I un-delete your solution? I can help edit it to explain how Riemann integration is affected. I think the discussion is a great learning point for the community. – Calvin Lin Staff · 1 day, 6 hours ago

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Now, I'm thinking to write an exhaustive solution for my last problem, and it will take me very long, because I'll deal vectorial spaces, prehilbert and Hilbert spaces, "dot products", problems with best approximation, orthoganility, minimax and Chebishev theorem, Gram Schmidt, etc... – Guillermo Templado · 1 day, 2 hours ago

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Note: For the example, if you don't like that \( \mathbb{R}^2 \) is an open set, then consider \( 0 \leq a, b \leq 6 \), and find the max/min of \( f(a,b) = [(a-2)(b-2) ]^2 \) subject to \( a+b = 6 \). You will notice that \( f(3,3) = 1 \) while \( f(2,4) = 0 \) and \( f(0,6) = 64 \) and so the condition of \( a = b = \frac{6}{2} \) does not yield a global max or min. Yes it yields a local max (but not min), but we have to check other turning points and boundary conditions as given by the complete theory.

I was trying to point out these errors to you and the community, so as to be aware and avoid such mistakes. Correctness/validity of logical deductions is important to the mathematical community but is often ignored in school. Even with an "intuitive approach", I still stress understanding the underlying reasons that explain it, since it could otherwise lead to an erroneous opinion. See this example

The solution of "minimize polynomial inner product" problem should be pretty straightforward with few pitfalls, esp if you have a good grasp of the underlying Hilbert space theory to explain the Gram-Schmidt process. – Calvin Lin Staff · 1 day, 2 hours ago

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– Guillermo Templado · 1 day, 1 hour ago

I can give a quickly proof of my last problem and it's not difficult, but myinterest lies in which everyone can understand the solution, which requires to develope much machineryLog in to reply

this problem not being the answer 2?. We have to have different definitions of impropial Rieman integral.... – Guillermo Templado · 1 day, 1 hour ago

How canLog in to reply

It is certainly possible that you have an alternative definition. As mentioned in my last comment of the deleted solution, you should state the definition that you are using. Be very particular about what conditions you are using. For example, in most texts, they start with the assumption that \( f\) is a bounded function, and do not reiterate that condition in every theorem/problem that they state. – Calvin Lin Staff · 1 day, 1 hour ago

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Sir, why is my slack account disabled? – Svatejas Shivakumar · 4 days, 9 hours ago

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– Calvin Lin Staff · 3 days, 4 hours ago

We are updating our process to develop an excellent community resource. One of the changes was to remove inactive Slack accounts, which is why your account was disabled.Log in to reply

@Calvin Lin sir I want to discuss the

factthat the new user interface has really made itdifficultto let your problem be discovered by others, and also discover other's problems.The old interface, where we had anormalcommunity feed was great and awesome.Please if possible, and by permission of other users, revert to the old community interface(I am referring to the interface that was around Jan-Feb).

Thanks! – Harsh Shrivastava · 1 week, 4 days ago

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– Calvin Lin Staff · 1 week, 3 days ago

Thanks for the feedback. I will look into it.Log in to reply

@Calvin Lin

Is it possible to downgrade all my levels to 1 and reset all the problems I have solved, so that I can start from scratch? – Andrei Golovanov · 3 days, 12 hours ago

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– Calvin Lin Staff · 3 days, 4 hours ago

Unfortunately no.Log in to reply

@Andrei Golovanov

possibly noif you are so interested in doing so... \(\big\text{"Create another account"}\) – Sai Ram · 3 days, 7 hours ago

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Just a note, no action needed. It really does make a difference when Brilliant.org adds or improves the graphics that appears in the community stream of featured problems. Even as something as simple as Icosa Hedron gets a lot of snap just by the addition of a picture of an icosahedron. I think it's effort well spent in attracting interest to Brilliant.org problems. – Michael Mendrin · 6 months, 1 week ago

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I will let the internet elves know that their work is much appreciated! – Calvin Lin Staff · 6 months, 1 week ago

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Calvin, I notice the new "median time to solve" feature. Is it in beta? In looking just at Level 5 problems that are not multiple choice answers, it can range from more than an hour to just a few minutes. In all of my Level 5 problems that are not multiple choice, only one median time was longer than 10 minutes, and many of my hardest ones, the ones that took me a long to solve, the median time is like 1 minute. How is it computed, that is, the time it takes for one particular solver? – Michael Mendrin · 1 year ago

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– Svatejas Shivakumar · 1 year ago

I too am confused with that. Also, I don't like the new feature saying that this problem is "very easy" for you or this problem is "very challenging" for you. It demotivates you if you can't even solve a "very easy" problem and I don't know why you get that message only after you get a problem right/wrong/after revealing a solution. It makes this even worse.Log in to reply

– Michael Mendrin · 1 year ago

My "Dubai Towers Perspective" is one of the very hardest problems I've ever had to solve before posting it. Brilliant.org says "easy for [me]". Together with the wildly inconsistent "Median time to solve", I think what's going to happen is that when those features don't seem to corroborate with practical reality, people will tend to stop paying attention to them.Log in to reply

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– Michael Mendrin · 12 months ago

Not to be a nag, but my curiosity is getting the better of me. What I keep asking is, say, for one particular solver, how is the time it took for the person to solve it measured? If users had to either solve the problem or forfeit once they "opened it up to look at the question" (like an exam!) then I think that is relatively clear cut. But what if the person clicks to see the question and answers it a week later? Or clicks it open repeatedly? Or, sometimes, is able to read the question without even clicking it open, so that once the person has the answer, is able to "answer it virtually instantaneously"?Log in to reply

I agree that "for features that don't seem to corroborate with practice reality, people will stop paying attention to them" – Calvin Lin Staff · 1 year ago

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I'm also noticing that information on the number of posted solutions is no longer provided, other than distinguishing between "no solutions yet", "discuss solution" and "discuss solutions". It's not a big deal, but I found that knowing that there were many posted solutions sometimes piqued my interest in a question. Finally, I notice that information on the number of reshares has disappeared. Again, not a big deal, since it generally correlated with the number of "likes", but the two values did occasionally differ significantly, which made me interested as to why that was the case. For me, resharing a question is akin to a more emphatic "like", (often after I have decided to spend the time to post a solution), so I tended to respond more to that value than the number of actual "likes".

Anyway, I know that it's always a work in progress, but I just thought a bit of feedback would be welcome. I was also going to mention that some of the discussion threads seemed to have either disappeared or been placed out of position, (particularly on older questions), but that problem seems to have been fixed now. :) – Brian Charlesworth · 1 year ago

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Sir, how does a problem gets rated? – Rohit Udaiwal · 1 year ago

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– Rohit Udaiwal · 1 year ago

OK thanks!Log in to reply

Sir, what is the way to post images along posting questions?

Is there any markdown or something else which would help me to draw pictures?

You can see that in all my posts, none of any one posts consists of pictures, geometrical diagrams.

Please help – Priyanshu Mishra · 9 months, 2 weeks ago

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sir does wrong answers affect my leveling up? – InkWhite 2000 · 6 months, 1 week ago

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stats page, you can see how your ratings change as you answer problems. – Calvin Lin Staff · 5 months, 2 weeks ago

Yes. On theLog in to reply