# Help talk:Editing/House Style

Why would one write f\left({x}\right) instead of f(x)? the {curly braces} have a purpose: in expressions like x^{35}, if one were to omit the braces and write x^35, then only the 3 rather than the 35 would appear in superscript. But when there's just one character, as in x^3, adding braces serves no purpose. Similarly one writes \left( BIG EXPRESSION \right) so that the parentheses will be big enough to enclose things like \frac{ \int_a^b f(x)\,dx}{\sum_{i\in I} blah}, etc. In things like (x+3), the \left and \right serve no purpose. The only place where I've seen things like \left({x}\right) before is when people who don't know how to write MathJax code use software to write the code for them. Michael Hardy (talk) 02:41, 25 July 2015 (UTC)

So as to centralise the discussion, best keep it at Talk:Riemann-Lebesgue Lemma or Talk:Main Page. But it'd be appreciated if you stopped implying that the contributors of this site are complete illiterates regarding TeX just because you cannot fathom the reasoning behind one of their decisions. — Lord_Farin (talk) 09:34, 25 July 2015 (UTC)
I never suggested anyone was an illiterate; I said that my experience has been that people who write MathJax code that way have been people who used software to write code that they didn't know how to write themselves. You'll notice I began by asking why it's done. Michael Hardy (talk) 00:33, 26 July 2015 (UTC)
And then continued by making a snide comment about your perception of their level of $\LaTeX$ literacy. If "The only place where I've seen things like \left({x}\right) before is when people who don't know how to write MathJax code use software to write the code for them" isn't such an implication, then what exactly was it? --prime mover (talk) 18:12, 26 July 2015 (UTC)
I'm not bothering to be part of this website any more so my opinion doesn't really matter, but here goes.
The long-term plan was always to facilitate the development of automatic theorem provers and further computer aids to mathematics. Hence a comprehensive plan to develop a completely consistent $\LaTeX$ style so as to ensure that when the software to develop such tools evolved (from my various contacts in the academic world of this, it's happening, but haphazardly), $\mathsf{Pr} \infty \mathsf{fWiki}$ would be in a position to capitalise directly upon this.
But as it seems that this is not what the rest of either the mathematics or the wiki world want, and they'd prefer the site to be as unstructured and badly-thought-out and presentationally haphazard as the appalling Wikipedia, I've given up on it in order to write novels instead.
I might also add that people who have contributed a large quantity of valuable material to $\mathsf{Pr} \infty \mathsf{fWiki}$ and have had committed a considerable amount of effort into its evolution are more likely to be listened to as regards editorial direction than someone who in the last 3 years since joining has contributed merely criticism. --prime mover (talk) 09:45, 25 July 2015 (UTC)
Wikipedia has many faults, but it is an entirely unprecedented and extraordinarily valuable contribution to humanity. Could I ask how users who come here are supposed to know that the purpose is to write machine-readable proofs to be checked by software? If a site like this is to be worth something, most of the people reading it will not be major contributors and will not go looking through various manuals on how to contribute, so where would they learn that machine-readability is what this is for? Michael Hardy (talk) 00:35, 26 July 2015 (UTC)
This matter has been raised repeatedly, and was a high-profile issue at around the time you joined this site. The discussion about machine-readability and interfacing with AI projects was discussed around that time IIRC.
No mention has been made about this long-term strategy in the house rules because that is not what the house rules are for. To that extent, users who come here don't need to know this strategy (it's merely incidental), but if they care to explore the site in some detail they will sooner or later come upon it. Is it necessary to know the complete history of the English language in order to know how to spell? --prime mover (talk) 18:12, 26 July 2015 (UTC)
Knowing the history of the language does serve as a way to remember some spellings. If a mathematician comes here and knows what is good usage in LaTeX and MathJax in the world at large, and is not aware that there are reasons why you want to do things differently, you will have trouble getting them to follow your conventions. What if your style manual required a lot of non-standard spellings without explaining that you have reasons for that? That would be a comparable situation. Michael Hardy (talk) 21:03, 26 July 2015 (UTC)
So are you going to contribute to this site or just spend all your time critiquing it? The $\mathsf{Pr} \infty \mathsf{fWiki}$ style manual is what it is, and the history of the site is such that changes to the style are unlikely to be implemented when they come as suggestions from people who have not contributed materially to its growth. --prime mover (talk) 21:42, 26 July 2015 (UTC)
I don't know. My recent attempt to contribute in a minor way to the site, which led to this discussion, didn't go over that well. But maybe I'll add something at some point. Michael Hardy (talk) 00:00, 27 July 2015 (UTC)
Sorry, my imprecision leading to misunderstanding. By "contribution", I was specifically referring to an edit that increases the amount of mathematical content, not one which either just amends the cases of section headings or changes the structure of source code. --prime mover (talk) 05:04, 27 July 2015 (UTC)

So, what is the reason for the curly braces?

(What a pointless deviation from the question and waste of time. Quit the personal judgments, focus on the real issues, explain why you do the things you do when asked, emphasize the positive aspects of both ProofWiki and Wikipedia instead of this self-deprecation and hollow words, and you'll attract good contributors instead of losing them. For some self-reflection, filter out the sentences above that meet these criteria. End of discussion. Now, forward!) --barto (talk) 12:38, 24 August 2017 (EDT)

You mean besides the FAQ entry Help:FAQ/Questions about contributions/Why do we need \left and \right with every pair of parentheses?Lord_Farin (talk) 13:47, 24 August 2017 (EDT)
Thanks! --barto (talk) 14:55, 24 August 2017 (EDT)

## Let vs. Suppose

I find it strange to use "let" to make assumptions about objects that are already defined. I thought "let" is used to introduce objects, not to impose conditions on them. Example:

Let $f$ be continuously differentiable.

Let $f'$ be monotonic.

It's strange, unnatural; it's like obliging $f'$ to be monotonic, as if $f$ is existent an nonexistent at the same time. If even here "let" is preferred over "suppose", then is there any example where "suppose" is used? I feel like there's a tendency to replace every instance of "suppose" by "let", in theorem statements and definitions. --barto (talk) 15:59, 28 January 2017 (EST)

"Suppose" is used on $\mathsf{Pr} \infty \mathsf{fWiki}$ when the existence of the object under discussion is under question. "Suppose that there exists a subset $S$ of $T$ such that $|T| > |S|$", for example, and the object of the exercise is to prove or disprove that existence.
"Let" is consistently used to specify and sub-specify and sub-sub-specify the object that is being defined as being what it is your defining. --prime mover (talk) 16:05, 28 January 2017 (EST)
Seems like, with that logic, they're interchangeable:
"Suppose that there exists a subset $S$ of $T$ such that $|T| > |S|$" vs.
"Let there exist a subset $S$ of $T$ such that $|T| > |S|$" or
"Let there be a subset $S$ of $T$ such that $|T| > |S|$" or
"Let $S$ be a subset of $T$ such that $|T| > |S|$"
IMO, this is also specifying/making assumptions or whatever one may call it. But okay, if you don't want to relax this rule, there's no use that I keep asking for it. --barto (talk) 16:17, 28 January 2017 (EST)
But there is no subset $S$ of $T$ such that $|T| > |S|$, and this is the important thing which is to be proved in the example above. Hence the "suppose" which is "hypothetically, imagine the situation where ..." whereas "Let $f$ be monotonic" implies "We are further going to specify that $f$ is monotonic" and so on. Each invocation of "Let" is a further restriction on the conditions of the object being specified.
This is on a par with the LET command in BASIC, where LET A = B is used to mean: It is to be specified that the variable A is to be assigned the value held in the variable B, and is a command for the computer to do something.
It makes it easier to understand exactly where the definition begins, and where the definition ends. --prime mover (talk) 16:26, 28 January 2017 (EST)