Talk:Main Page

The use of Q.E.D.
Although considered "traditional" in the field of mathematics, the use of "Q.E.D." is apparently, I believe, considered somewhat archaic nowadays, and a bit (perish the thought) camp. I believe (from reading around the subject and general communications) that a more common way of signalling the end of a proof is by using the symbol "$$\blacksquare$$" (whose LaTeX is \blacksquare) at the far right of the page, and for a subproof (e.g. a lemma proved in the course of proving a particular result) "$$\Box$$" (whose LaTeX is \Box).

What does anyone think? I have consistently not used Q.E.D. in any of my proofs, but then I haven't been using $$\blacksquare$$ either (mainly because it wasn't available when ProofWiki started and I never got into the habit). If we decide that the "house style" is to include Q.E.D. can we agree that it goes in a particularly fancy font, and have a template link in the ProofWiki Specific section?

Happy Hogswatch to all, btw. --Matt Westwood 07:45, 26 December 2008 (UTC)

I'm fine using either one, either the use of Q.E.D. or the squares. Since the use of Q.E.D. is on the way out we should probably use the squares, I'll make a template.

My thoughts are to have it called qed, and have a option for writing say and then it would put a white square, otherwise a black one. Thoughts? --Joe 16:51, 26 December 2008 (UTC)

No objections either way, although I've never been entirely convinced that adding QED at the end of the proof really adds anything (the proof is over, it should be obvious that it's done). That said, if we do use the square, I don't think it should be all the way to the right, I previewed a page with it and was looking for it, and I still missed seeing it the first time around. --Cynic-(talk) 17:09, 26 December 2008 (UTC)

I've noticed that too, maybe we should just have it so that it's put directly at end of last statement.

For example:

Therefore, $$x=\pi$$ $$\blacksquare$$

Thoughts?--Joe 17:18, 26 December 2008 (UTC)

Maybe put in some space before the box: Therefore, $$x=\pi\qquad\blacksquare$$

Unfortunately, putting a spacing command in (\qquad for example) at the beginning of a math section doesn't do anything, so it would be hard to have it be a template. I don't know if you can create your own functions for wiki LaTeX like you can on standard LaTeX, if you can, you could always make a \qed command. Also, don't put periods in after the box, it looks weird. --Cynic-(talk) 21:22, 26 December 2008 (UTC)

"Therefore, $$x=\pi$$ $$\blacksquare$$" works for me, although I wonder whether it might make the looknfeel more consistent to put it on a new line.

"My thoughts are to have it called qed, and have a option for writing say and then it would put a white square, otherwise a black one" works for me as well.

STOP PRESS: I've just got my hands on "Theory of Sets" by Bourbaki (happy xmas, father-in-law) and in the very second line of the mathematical exposition he uses $$\Box$$ as one of the symbols:

"The signs of a Mathematical Theory $$\mathcal{T}$$ are the following:


 * 1) The logical signs: $$\Box, \tau, \vee, \rceil$$.
 * 2) The letters."

Either this is going to have to be translated into a more "conventional" symbolism (goodness, that will take me a day or two, this book is hev-VEE) or we're just going to have to be really careful. --Matt Westwood 23:09, 26 December 2008 (UTC)

Well, as we're dealing with the geometry that's being posted, another issue has occured to me. \Box seems to be the best choice to be the symbol to represent a quadrilateral. We could always use $$\Diamond$$ (\Diamond) but I think \Box works better. Or it might not be an issue, since it would always appear before letters when representing a quadrilateral and on it's own line when representing QED. Thoughts? --Cynic-(talk) 21:13, 30 December 2008 (UTC)

Might not be a problem. The use of \Box for the end of a lemma is going to be rare because it's more usual for such sub-results to have their own pages anyway. In fact that might be a useful general recommendation, i.e. to put all lemmas on their own separate pages, what say? Then the issue wouldn't arise, we'd just have $$\blacksquare$$ for proof endings. --Matt Westwood 22:18, 30 December 2008 (UTC)

I agree. --Joe 01:07, 31 December 2008 (UTC)

WLOG and WRT
Would it be a useful idea to have a page for abbreviations?

Thus one could write WLOG for "without loss of generality" and WRT for "with respect to" and so on.

The initial thought as I started writing this post was to streamline the development of complicated proofs but the counterargument is that it may make the proof less transparent to a noobie. --Matt Westwood 10:10, 29 December 2008 (UTC)

I would make a Symbols:Abreviations page to put them on, but I wouldn't link them, it'll just make proofs look a lot more complex. Besides, I think anyone who is interested enough to read a difficult proof knows what something like WLOG means. --Cynic-(talk) 16:54, 29 December 2008 (UTC)

I think we could even put them in as definitions. --Joe 16:57, 29 December 2008 (UTC)

I don't see how it would make proofs more complex, you'd just get WLOG appearing in blue. The only added complexity would be to the source code, and that should not really be a concern in this context.

I mention this point because there's already confusion with "iff" which I would have expected undergraduate level mathematicians to be familiar with (I had to uncorrect someone a few weeks ago who "corrected" what he thought was a spelling mistake for "if"). So I'm starting to consider linking "iff" with its def nowadays. --Matt Westwood 18:33, 29 December 2008 (UTC)