User talk:Oscarlevin

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Revision as of 07:55, 18 October 2010 by Zerrakhi (talk | contribs)
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Solutions over multiple lines

I visited the site following the link in your comments on Richard Wiseman's most recent Friday Puzzle solution, and thought I'd see if I could contribute.

However, I can't contribute a solution because the wiki won't accept a solution that takes more than one line. For example, this doesn't work:

{{Solution | 

Pretty much all solutions will require multiple lines, so this is a real problem. I assume a "solution" means an answer with working, whereas an "answer" is just the answer by itself.

Below is my solution to the 7 orbs puzzle, which I tried to contribute:

Let A = set of orbs for which there are 3 or more others the same colour.
Let B = set of orbs for which there are 1 or 2 others the same colour.
Let X = set of orbs for which there are no others the same colour.

Goal is to prove that some orb is in A.

Possible combinations:
(using the shorthand that A denotes an orb that's in A, etc)


Label the orbs 1, 2, 3, 4, 5, 6, 7 and test 1&2, 3&4, 5&6.

Comparing the results of testing those three pairs with the possible combinations, you can easily show that:

If two tested pairs glow the same colour, all members of those pairs are in A
If only one of the three tested pairs glows, members of that pair are in A
If two tested pairs glow different colours and the other doesn't glow, orb 7 is in A
If no tested pairs glow, orb 7 is in A.

In all cases, three tests suffice to prove that some orb is in A.

The only other thing required is to prove that two tests are not necessarily sufficient, which is trivial.

Is that the sort of thing you're looking for? Zerrakhi 12:16, 11 October 2010 (EDT)

Yes that is the sort of thing I'm looking for. I'll see if I can fix the multiple lines problem. Oscarlevin 15:06, 11 October 2010 (EDT)
So I can't seem to replicate your problem. Is it just that the lines are not breaking? Like this:

solution over multiple lines

Because that can be fixed will a line break between them, as in:





Or is there some other problem? Oscarlevin 15:25, 11 October 2010 (EDT)
The problem wasn't with your multiple lines, it was with the = sign. Templates allow you to have named parameters, which you assign with =. I don't know if there is a workaround for this. Oscarlevin 15:41, 11 October 2010 (EDT)
Ah. Never thought of that. I just tested in preview mode, and found that nowiki tags around the = sign seemed to work. I've written something up on the Editing Help page. Zerrakhi 19:27, 11 October 2010 (EDT)

No link in email

The email received upon registration, the one containing the words "open this link in your browser", does not actually contain any links or URLs to open! Zerrakhi 12:27, 11 October 2010 (EDT)

Did the email you get contain a bunch of <math></math> tags? I'm using an extension that switches dollar signs to math mode (ala LaTeX), and it has screwed up a lot of the system messages. I'll see if I can fix this too. Oscarlevin 15:06, 11 October 2010 (EDT)
Yes, that's right. Zerrakhi 19:27, 11 October 2010 (EDT)
This should be fixed now. Just testing a few things out. Test1 22:03, 11 October 2010 (EDT)

More questions

I'm wondering why only a few puzzles are in the needs solution category, and likewise for other similar categories. What's special about those puzzles in particular?

Because the 7 orbs puzzle is listed first on the front page, I assumed it was representative, and that all puzzles would have a hint, answer and solution in the same format. Now that I've seen that's not the case, I'm less sure about how I can contribute further. (Except by asking pointed questions, of course.) Zerrakhi 09:38, 12 October 2010 (EDT)

The only thing special about puzzles which have "needs ___" on them is that I happened to include that when I first put them up. Some puzzles were supplied before I had created those templates, and others after but I forgot to include the reminder. So for any puzzle you see on here that you think deserves a hint, answer or solution, feel free to provide one.
There are other things you can do, if you like. If you know of another puzzle, please add it. You can also improve current puzzles by giving variations, more references, links to similar puzzles, or notes on the mathematical content. In addition to being a collection of puzzles, I hope this wiki becomes a resource for math teachers. So any comments about how a particular puzzle relates to a mathematical concept are welcome. Finally, if you have any further ideas on how to improve the wiki, I'd be happy to hear them. Feedback is always good. Oscarlevin 10:18, 12 October 2010 (EDT)
I think it would be a good idea to add a page specifically on this topic: a list of ways in which people can contribute. That would also be a good place to summarise the most important templates.
Good idea. I've started doing so.
Don't forget to add links to pages like that from the front page so people can find them... Also, what about adding the needs_hint, needs_answer, etc templates? Is that something people can usefully do? Since the templates exist, it seems a shame not to use them consistently.
I'll give you a link from my blog sometime this week. (Not that it will do any good: very few people read it.) As for self promotion, nobody will mind if you mention it in a postscript next time you leave a comment on Richard Wiseman's blog; he's never discouraged people from using it as a giant conversation forum and it will reach a wider audience than I ever could.
Incidentally, I knew the lightbulb puzzle because it's been featured on Wiseman's blog in the past. Also, some time ago I nominated a puzzle that he has confirmed he will use in some future installment. If you want a spoiler, it's the...
Knights and Pages puzzle, a version of which can be found at . In the book I got it from, it comes in three parts: (1) as in the link, (2) proving there is no solution with four pairs of characters. (3) solving with four pairs of characters plus an island.
I'll have plenty to say about that when it gets to the top of the queue, but not before. Zerrakhi 09:33, 17 October 2010 (EDT)
Another thing that seems strange is the requirement to log in before viewing a solution. I would question the sense of that, because the audience of people interested in contributing to the wiki is distinct from the audience of people interested in using it as a resource, and members of the latter probably won't bother to create accounts (especially when most puzzles are searchable). But perhaps I misunderstand how you envision the site being used. Zerrakhi 06:12, 13 October 2010 (EDT)
The reason for trying to restrict solutions is that I want to make it difficult for students to use this site to cheat. I teach a variety of college courses where I use puzzles from this site as either extra credit assignments or as the beginnings of homework problems. If a student finds the site by searching for the puzzle, I would rather they feel intimidated by registering (because maybe they think I would see their email) and try to do the problem on their own. But I do want to have solutions somewhere to help remind me how difficult the puzzle is in case I forget how to solve it.
I envision the site to sever as a collection of good math puzzles, with perhaps a discussion on why they are mathematically interesting. These puzzles are meant to puzzled over, not answered by a web search. Thoughts? (I probably should outline this "policy" on a help page as well.) Oscarlevin 22:03, 13 October 2010 (EDT)
Not a lot of relevant thoughts, but as you probably guessed, that was largely my reason for asking - to suggest things that would be useful to mention on the help pages. Zerrakhi 09:33, 17 October 2010 (EDT)

Something's wrong...

All of a sudden, I find that the hint/answer/solution boxes are open by default, so that I can read their contents without wanting to! What could have caused this? Zerrakhi 09:55, 18 October 2010 (EDT)