# Is the rollback attempt in this thread appropriate?

This is an issue with this specific question. Please look at the revision history here. I merely improved an attempt by the asker (which was written as a comment), making it clearer. I did not change any essence of the question or the attempt. However, a moderator deemed that the revision broke the guideline and reverted the changes. Per this chat here, the moderator thinks that my edits changed the computations the asker performed in their attempt. I disagree. Everything I wrote was the same as what the original version, only I made the idea more rigorous (the aim was mostly to help the reader understand the procedure made by the asker).

Here is the version the moderator reverted to:

Given a sequence $$S = (p_0, p_1,...,p_{n-1})$$ of integers, what is the smallest possible degree of a polynomial $$p(x)$$ such that $$p(i) = p_i$$, that is, the value of $$p(x)$$ at $$x = i$$ is $$p_i$$?

Edit: I got it. Keep updating the sequence such that $$p_i := p_{i+1}-p_i$$ and the last element is removed until all its elements become equal. Number of steps is the required answer

Here is the improvement I made:

Given a sequence $$S = (p_0, p_1,...,p_{n-1})$$ of integers, what is the smallest possible degree of a polynomial $$p(x)$$ such that $$p(i) = p_i$$, that is, the value of $$p(x)$$ at $$x = i$$ is $$p_i$$ (the smallest degree depends on the sequence $$S$$)?

Edit: I got it. Keep updating the sequence by creating sequences $$\Big(p_i^{(k)}\Big)_{i=0}^{n-1-k}$$ such that $$p_i^{(0)}:=p_i$$ for $$i=0,1,2,\ldots,n-1$$, and $$p_i^{(k)} := p^{(k-1)}_{i+1}-p_i^{(k-1)}$$ for $$k=1,2,\ldots,n-1$$ and $$i=0,1,2,\ldots,n-1-k$$. The number of steps $$k$$ required such that $$p_0^{(k)}=p_1^{(k)}=p_2^{(k)}=\ldots=p_{n-1-k}^{(k)}$$ is the required answer.

Can anybody explain to me how the computations in the two versions are different? I would like an opinion from different moderators or other users. (Lastly, the attempt by the asker is much more than an attempt. It is the correct answer.)

• Going from "updating the sequence such that $p_i:=p_{i+1}-p_i$" to "updating the sequence such that $p_i^{(k)}:=p_{i+1}^{(k-1)}-p_i^{(k-1)}$ for $k=1,\cdots,n-1$" is okay IMO -- this is common syntax in programming, but I feel that adding the $n-1-k$ parts is assuming that the asker knows that termination point... which isn't always obvious to everyone.
– TheSimpliFire Mod
Sep 4 '20 at 15:27
• @TheSimpliFire That's fair, although I think it is quite obvious. However, the asker knows that each step reduces the number of entries of the sequence (see the asker's original comment here). The asker says "[...] the last element is removed [...]." Sep 4 '20 at 15:30
• So I think something like "I got it. Keep updating the sequence by iterating $p_i^{(k)}:=p_{i+1}^{(k-1)}-p_i^{(k-1)}$ for $k=1,\cdots,n-1$. The last element is removed until all of $p_i^{(k)}$ are equal. The number of steps $k$ is the required answer." would be sufficient, but not to the extent that it might assume something the asker may not know. I really appreciate your doing this, but remember that the asker's attempts don't always have to be perfectly rigorous.
– TheSimpliFire Mod
Sep 4 '20 at 15:30
• @TheSimpliFire I simply wanted to help the reader understand the procedure. The asker understood what they meant, but readers do not necessarily understand, especially when they are not used to computer coding language. Sep 4 '20 at 15:32
• Directly editing into users' posts isn't how that's done though; helping users understand is best done through an answer (where you can explain the procedure), or a comment if you want to give hints.
– TheSimpliFire Mod
Sep 4 '20 at 15:33
• @TheSimpliFire I made a new edit. Does this one look better? This new edit contains no extra information at all. Sep 4 '20 at 15:36
• Thanks for removing the $n-1-k$. I'd be tempted to also remove the "creating sequences part" though -- as a general rule of thumb, I'd stick to the asker's own words as much as possible. The "constant sequence" part I'm okay with, as it's the same as "all elements are equal."
– TheSimpliFire Mod
Sep 4 '20 at 15:39
• @TheSimpliFire I did as suggested. Your input is very much appreciated. Sep 4 '20 at 15:42
• IMO it's fine now (others might have different standards but I don't think you've gone overboard with it), just remember not to add/deviate too much in future edits. I appreciate your contributions to improve the site.
– TheSimpliFire Mod
Sep 4 '20 at 15:45
• It is tempting to "make things more rigorous" but in fact the essence of a Question is often not knowing how to make things rigorous, or even how to articulate that a lack of rigor is the difficulty. Those kinds of changes, in the body of a Question, are best left to the OP (perhaps prompted by your commenting on how it should be done). If the prompting is not effective, then I'd suggest posting an Answer laying out the implications of your proposed "rigorous" statement of the problem. Sep 4 '20 at 16:04
• I don't think your attempt to transcend the rollback was appropriate, Batominovsky, at least not until a moderator addresses your question. Sep 4 '20 at 16:07
• @hardmath That's a fair assessment. I don't think that it really applies to this thread in particular. The OP didn't get stuck with how to make the question/answer rigorous. Plus, the OP very much self-answered the question. Sep 4 '20 at 16:08
• As one of the active users in the CURED room, the mentioned moderator is doing way too much to insert his own opinions on such a post. "In any event, I have told you that the edit was inappropriate. I am not going to continue this conversation any longer." Such confrontational messages are best avoided by mods, it needed at all.
– user9464
Sep 4 '20 at 16:44
• @T.S the comment you've linked to is in the GENTLE chatroom not CURED, and is only part of the complete comment. That rather makes your comment here look like misrepresentation. Sep 4 '20 at 18:22
• @T.S In light of your above comment, and postmortes's fact check of your misrepresentation, including your repeated attempts to find fault with all activity in CURED, (when in this case the comment you object to is in GENTLE), I believe you speak of yourself: you have been doing way too much to insert your own opinions in meta matters. Sep 4 '20 at 20:08

Attempts differ from other forms of context in that they are deliberately localized-- that is, they convey information that is primarily relevant for helping the OP, rather than future users. They are intended to be a space where OP can state their progress towards a problem in their own words.

The attempt implicitly conveys details about OP's background, way of thinking, level of mathematical maturity. This provides diagnostic value when constructing an answer-- what will OP understand? What might be overwhelming? What aspects of the problem have yet to be considered?

To preserve this information, edits to attempts should be limited to very minor revisions, such as formatting improvements, basic grammatical corrections, or MathJax. It is good to want to help OP to clarify or develop their attempt, however the appropriate place to do this is in the comments.

Going back to your example specifically:

• as TheSimpliFire brought up, adding $$n-1-k$$ is something the OP may not know. This could have been where they were stuck.

• does OP really know how to formulate "Number of steps is the required answer" explicitly? If this is in the attempt, it is unlikely to be explained.

• even just indexing by $$\Big(p_i^{(k)}\Big)_{i=0}^{n-1-k}$$ can be overwhelming to students at some skill levels. If the attempt uses this notation, answers are likely to use it, and possibly be less intelligible to OP.

• The way I see it is: the OP already has a correct answer. Therefore, the OP is no longer in need of an answer, so there is no harm to make the OP's attempt, which is in fact an answer, more understandable to other people. But thanks for your input. Sep 4 '20 at 21:17
• @Batominovski That's not how this site works. Your answer is sufficient to make the answer understandable to people. Just please don't put words in askers' mouths. If they had them to begin with, they wouldn't be asking, now would they? Sep 4 '20 at 21:33