CURED

user21820

4:49 AM

@ParamanandSingh Oh I didn't notice, because I don't look below the PSQ haha..

user21820

5:04 AM

@TeresaLisbon 1 more downvote to deletability.

@MartinR Down for deletion!

Paramanand Singh

@user21820: I can understand, PSQs are not worth the time to analyze in detail with the list of all answers and comments.

Paramanand Singh

5:26 AM

close this PSQ

Teresa Lisbon

5:57 AM

@ParamanandSingh Self-deleted.

SmokeDetector

6:09 AM

[ SmokeDetector | MS ] Potentially bad ip for hostname in body, potentially bad keyword in body, blacklisted user (73): Is it.... every number goes through digit 9? by mykar2un on math.SE

Peter

8:43 AM

Is the answer of this question actually valid in the sense that the modern compass solves the "squaring the circle" problem in the same sense as an angle can be trisected ? I have doubts , but maybe I am wrong.

Paramanand Singh

9:08 AM

@Peter: squaring circle amounts to constructing a transcendental number. And tools which can draw algebraic curves (ie their equation is algebraic) should not lead to an algebraic number.

But don't trust me on things related to abstract-algebra

Arctic Char

9:19 AM

Might consider deleting this answer (it was discussed on meta).

Peter

@ParamanandSingh you mean "should not lead to a transcendental number" , right ? This is exactly what makes me sceptical.

@ArcticChar I think, deletion is justified.

Paramanand Singh

@Peter : yes you got it. Sorry for that kind of typo.

Paramanand Singh

9:41 AM

This thread was created after deletion of a previous question by same user.

Don't know how to deal with this.

Peter

D

user21820

10:10 AM

@Peter Paramamand is right. Trisecting an angle is an algebraic operation in the sense of modern algebra. A straightedge allows you to solve linear equations. Adding a compass allows you to solve quadratic equations. Adding a 2-marked straightedge allows you to solve cubic equations, which suffices for trisecting an angle.

Note that this is actually physically as realizable as a compass, namely if your ruler has a sharp end (which you take as one mark), you can stick a pin at A and put a straightedge alongside BD and then slide the marked ruler in contact with that pin dragging its end along BD until the other mark touches the circle (at C), and then you're done.

In contrast, squaring the circle requires constructing a non-algebraic number which I think is impossible via any idealized mechanical device.

Paramanand Singh

@user21820: thanks for the confirmation. I know some theory about ruler and compass construction, but not that confident.

Teresa Lisbon

@Peter It's deleted, but I think a better close reason would have been that it is too broad (in the sense of "why is separation/clustering important in life?"), and/or was better suited to the educators site. If it was on the educators' site, I'd have surely had a crack at it, although I'm sure someone would have done better.

user21820

@ParamanandSingh By "mechanical device" I meant rigid devices, so excluding loose-hanging strings that we can use to construct transcendental curves like the catenary. But I could be wrong about that last claim. In any case π is certainly not an algebraic number, as you stated, so neither is √π.

Teresa Lisbon

@ParamanandSingh The previous question has been undeleted, and now I think things are good, except the user needs a warning.

user21820

10:28 AM

@Peter But concerning that specific answer, I don't know enough about Galileo's compass to judge whether that answer is misleading or not. In particular, if it comes with a logarithmic slide rule, then one could argue that it can be used to obtain certain transcendental constants just by treating it as a marked ruler (with idealized marks). If it happens to have both π and 1 marked on it, then sure we can construct √π, in which case the answerer is correct that it is just cheating.

But the question is bad and I think we all agree that it should be closed.

Paramanand Singh

@TeresaLisbon: glad to hear that. But still i don't get the point of deleting one's own question. Creating two threads on same topic when the first was sufficient does not make much sense

@user21820, @Peter: that Galileo question is now closed.

Teresa Lisbon

@ParamanandSingh That is correct. However, there were circumstances I can imagine (such as the answerer not responding, or leaving a framework the OP wasn't able to complete, etc.) that could have led to the creation of a second thread. The user needs a warning, however.

Paramanand Singh

I had already left a comment there to that effect @TeresaLisbon. So perhaps we don't need anything more there.

Teresa Lisbon

@ParamanandSingh ok, great, good, well , done.

oh no, left finger was on the commas there, sorry.

Paramanand Singh

No issues

It does sound like go, went, gone

user21820

10:41 AM

Delete this PSQ to make this PSQ deletable.

Teresa Lisbon

@user21820 Second one can go now.

user21820

@TeresaLisbon Thanks! One more vote to go.

Teresa Lisbon

@user21820 Gone!

Peter

@vitamind Do you know why Martin Hopf has not been seen since 4 days ?

Teresa Lisbon

PSQ

Teresa Lisbon

11:05 AM

Before you start your day on CURED, listen to this

How exactly does the "last seen" work? I saw a user's profile, they were last seen 26 minutes ago but posted a question 14 mins ago , which is here and can be deleted if required.

Peter

The new comment in the galileo question seems to mean that this compass uses $\pi\approx \frac{22}{7}$ , in which case, it is just a measurement with sufficient accuaracy. I do not know what this compass actually does, but considering this comment, there seems to be nothing about construction of $\pi$

vitamin d

@Peter Mmh, no. I hope to see him by April 26th at the latest...

user21820

11:37 AM

@Peter Wow that would be an oracular compass! And you're right, the more we hear the less it makes sense. Reminds me of...

in Jokes, May 8 '19 at 10:07, by user21820

The more cheese, the more holes. The more holes, the less cheese. Therefore, the more cheese, the less cheese.

The question is now up for deletion!

user21820

11:59 AM

0

A: How likely is it that a question with 2021 is from a current contest?

To answer the titular question: The likelihood that a question with 2021 is from a current contest is $1-\dfrac1{2021}$. Well, we all know that this likelihood was already quite high even before Math SE came around, and it only increases over time for questions on Math SE, since cheaters have f...

Martin R

@TeresaLisbon As I understand it, “last seen” is intentionally inaccurate, e.g. in order to protect some privacy. You can find some information in this Q&A and its comments: meta.stackexchange.com/q/285220/196432.

With a precise timestamp it would be easier to associate votes with people.

user21820

Wrong answer because a bounded sequence need not converge.

Teresa Lisbon

12:18 PM

@MartinR I ,see, thanks.

@user21820 But the question is, why does it not blow out, right? I think that has been addressed somewhat.

user21820

@TeresaLisbon The question is addressed well by the other answer. The fact that the asker asks such a question means that the asker does not have the capability to understand what is missing from the post I linked. The point, anyway, is that that post is wrong because it claims existence of limit from just boundedness. It didn't even say anything about that.

Teresa Lisbon

@user21820 Ah, yes, that is certainly true. Now it remains to convince the OP of the same.

vitamin d

12:36 PM

@MartinR Could you please send the comment you wrote under this post? (With the hyperlinks so I (we) can easily copy-paste it? And by the way, please close this PSQ.

Martin R

@vitamind You can find that (and other useful comment templates) here:

144

Q: List of comment templates

Inspired by this question on meta.cstheory.SE. The post at meta.Tex.SE is quite impressive. We often leave generic comments to OP and answer posters such as "if this is a homework, please add a tag," and such. Can we make this post a community wiki and add a big list of standard comments? Let's ...