Carl Mummert

@spaceisdarkgreen: In your comment above, it looks like the matrix of (1) is a $\Sigma^0_1$ formula, which I suppose is proved by induction on $k$, and the $k(n)$ in (2) is basically just the CNF corresponding to $n$ in the proof of Goodstein's theorem. So, based on your explanation, it also looks to me like $I\Sigma^0_1$ would suffice.

@spaceisdarkgreen That is helpful, thanks.

@btilly I am a little confused - if we have a model $M$ of PA and a (nonstandard) number $x$ in $M$ so that $M$ does not satisfy $G(x)$, I'm not sure how to see $M$ satisfies $(\exists p) P(p,\ulcorner G(x) \urcorner)$. Is this obvious?

In some sense, excluded middle is more applicable outside mathematics. The LEM is most useful when we are thinking about some concrete model, in which each statement is true or false, and trying to reason about properties of that model. To the extent that reality itself has objective truth values, it makes perfect sense to use LEM to reason about them. The purpose of not using LEM in constructive mathematics is because we want to understand human knowledge, rather than objective reality - which seems quite different from the goals of physicists.

I would like to see a compromise, if the moderators will be willing to stand behind one. Nothing is ever going to find unanimous support. We need a way for the site to make a decision which is binding even on those who might disagree with it.

I see - thanks for pointing out how recent that change is

I want to browse through the questions in the infinite combinatorics tag, but I need to catch up on a lot of email first

No problem, I am still thinking about it and about the tag wiki

@Martin: I am looking at it. Some of the smaller parts of infinite combinatorics are close to what I do - things related to Hindman's theorem and Ramsey's theorem. But not too much in set theory

Depends a lot on the moderators :)

Agreed

In this case, anyway, I think the duplicate is pretty clear and not much discussion will be needed

I agree that would be the other option - but I had thought if someone posted a separate question about re-closing a post, the meta question would be viewed as a duplicate of the "requests for reopening"

I'm not trying to be too argumentative here; as I was saying, I think CRUDE is having some issues, and I did some reflecting on the advice of a non-math moderator who posted there yesterday to point out that the meta site is the intended place for people to discuss site policies and practices

I'm still not sure why the same thread is not ideal for both.

@quid: there must be somewhere on meta to discuss, for example, a question that was re-opened when it should not have been. IMO that kind of discussion is exactly the point of the meta site.

It does leave the question of where on meta to request re-closure or re-deletion, but that doesn't need to be solved for this

Thanks - that will work for the post I have in mind.

Hello Martin. We're discussing the right place on meta to request re-closing of a question.

I don't mind opening a separate thread on meta, although it seems like it has the potential to be more acrimonious, and it may get tiring to everyone to have a number of "please close this question" threads on meta

I have deleted the post for now, until I figure out what to do with it. I am not planning on posting anything to CRUDE for a while, as it has been growing increasingly problematic, and in any case the meta site is intended for this kind of thing, rather than chat (which is why we don't shovel all the reopen requests to CRUDE as well).

@quid - I was not trying to post something off topic in the thread, but I am now not sure what the reason was for changing the scope of the most recent thread vs. the previous ones, if the scope is now different?

@ArtOfCode: that sounds like a good idea.

No, I don't know which message you meant. If you have a specific idea for how each side would change what they are currently doing, great. But I honestly don't see it above, perhaps I missed it

or just copy it again

Can you link to where you said how both sides would change what they are presently doing?

So both sides would avoid voting to open or re-close if a respected, experienced member of the other side made a comment that they really want the question to be open or closed?

We can go back and forth like that forever - if you are looking for a compromise, give an example of how both sides could change their usage of the site. I'll wait for it.

As I said, the other side is also compromising by not closing many more questions that are of dubious quality, but not extremely dubious quality

There is also the issue that there's no way to tell who is a "respected" member of the community, apart from possibly moderators.

But if you chase this to its conclusions you end up with basically a separate copy of the current system.

@BillDubuque: one could equally say that when respected, experienced members vote to close something, others should respect that. It's not a solution if it looks like one side just gets what they want. One option might be some kind of comment, where if someone says "I really want this open" then nobody should close it, but if someone says "I really want this closed" then nobody should open it.

@BillDubuque There is also the possibility that people who close questions have also compromised by not closing other marginal questions. There are many questions which fall short of the guidelines for the site but not so much that they are closed. For example, many questions for which the "context" consists of nothing by failed effort fall into this category.

@BillDubuque: if you are interested in working out a compromise, please explain what it would mean for each side. How would people who close bad questions change their usage of the site? How would people who answer them change their usage of the site?

Here is the meta question about how to handle an old question/answer math.meta.stackexchange.com/questions/29926/… . The person who wrote the old answer has deleted their account, so pinging them about it isn't possible.

This question, which was mentioned on meta right now, seems to be a duplicate. D1

It's true.

@Xander Henderson: I read the question as "how could a calculator compute things", rather than "how do existing calculators compute things".

Sounds good.

In particular I don't see why the answer should be deleted - I have always thought that comments explaining the issue were more appropriate than deleting individual answers, unless the answers are completely gibberish or off topic.

I'm not sure we can judge their knowledge from one post - and the method they have does work in theory, after all. A comment that calculators don't use that method might be appropriate, but I don't see how the answer is misleading, since I read the question broadly

I would read the question more broadly, but I do see how it could be read that narrowly. If the question really is about specific calculators, I'm not completely sure it's on-topic - too specific. But if it is about all the ways that calculators could do it, I would think it is more on-topic

@user21820: it asks how to compute sin and cosine, and the answer gives a possible way. For all I know the person did write a calculator program that used that method.

@BillDubuque: if you would like to propose a compromise - in which all sides would adjust their use of the site - please do, I am still interested in it. In the past the problem was that not all sides were willing to adjust their use of the site.

@user21820: I can follow that last one, it seems they are just normalizing 90 degrees to 1 and then writing the desired angle in binary and using the sum of angles and half angel formulas.

@rschwieb: I think that the question is confusing, but I can guess what the OP might hav meant. Pity they deleted it rather than clarifying, maybe they will clarify at some point

Ping me if you ever want the code

but we should discuss that in a separate room, if you want to talk about programming, for the sake of non-programmers here :)

Perl, then C

I did it fro the left, but if you only look at the list of potential divisors at each step then I don't think it would be more convenient to do it from the right