Scarlet Manuka

I often find that the Answer feed only shows days-old questions even though newer ones exist. For instance, 10 minutes ago I saw several questions in the Mathematics feed from the last few hours, but now I can only see one recent one and then it immediately skips to "3 days ago". Taking off the "No Best Answer" filter has no effect.

It appears that HTML character entities are no longer allowed in answers - as a frequent answerer in the Mathematics category I made extensive use of these so that I could type π, √ ∫, ∂, ∈ and so on rather than having to dig up a character map and copy and paste π, √, ∫, ∂, ∈, etc. which is far slower and very inconvenient.

Any chance of getting them back?

I would dearly like a media player that's suitable for classical music (95% of my listening material). Every new version of Windows Media Player seems to be harder than the previous one to use effectively with classical music, and now I'm on WMP 11 I'm finding it very frustrating.

I have no problem with manually entering the track info for every track; I'm used to this anyway. My issue is more along the lines of organising my music. Principally, I'd like to be able to organise my media library by composer as well as by album title. I'd like to be able to do this for on-disk storage too. I'd like a media player that doesn't insist that the performing artist is the most important thing I need to know.

I don't necessarily want something that's explicitly geared towards classical music (though if such exists, I'd be grateful for a link). Something that's configurable enough for me to tell it how I want it to deal with my music is all I want. Does anyone know of anything like this?

I'm looking for a good free MIDI player.

Currently I'm mainly using vanBasco's Karaoke Player. It mostly does a good job, but I particularly miss some of the features I have on an old and no longer updated player, MegaMID. Specifically the ability to change instruments on the fly, and the excellent note display of MegaMID (which shows pitch bends graphically, for instance; I dislike vBKP's note display in both forms, particularly its bizarre insistence that I should think in terms of a piano keyboard). Being able to adjust the volume of individual channels would also be nice (a feature I had on yet a third player that I used to use).

I don't need karaoke features, I don't need conversion utilities, I don't need notation or editing capability (though I'd probably use them if I had them; but I have other software that does a reasonable job of that). I just need a MIDI player that lets me change things around a bit more than vBKP.

In Excel there's a "Share Workbook" button on the Review tab, but Word doesn't seem to have an equivalent. All we want to do is put the document into shared mode so two of us can update it simultaneously.

I couldn't find anything in the help, and there's no "Share Document" command available (I checked with Customise Quick Access Toolbar > All Commands). Any advice would be appreciated!

Here's a nice little problem distantly related to some work I did way back when for my honours thesis.

In ring theory, an idempotent element is one which is its own square. In a ring with unity, 0 and 1 are always idempotents, but there may or may not be other idempotent elements.

Now the product of idempotents is not necessarily an idempotent. In my honours thesis I was concerned with characterising the elements that could be expressed as the product of idempotents. Here's a little problem relating this to the simple ring Z_n (n any integer ≥ 2).

a) Prove that in Z_n, the product of two idempotents is also an idempotent.

b) If n = p^r where p is prime, show that the only idempotents of Z_n are 0 and 1.

c) If n = pq where p and q are distinct primes, show that Z_n has exactly four idempotents and characterise them.

d) For arbitrary n ≥ 2, characterise the number of idempotents in Z_n in terms of the prime power factorisation of n.

Does anyone know of a good shareware / freeware registry tracer? I want to find out what registry keys a program is trying to look up when I run it, so I can import them from my backup.

(Background is that I recently upgraded my OS from 98 to XP via an OEM install, which of course blew away my registry - as I expected; I'd exported the original into .reg files so I could reimport settings later - XP's files and settings transfer wizard didn't grab the old registry entries to put on my new system, so I either have to import keys or reinstall apps, and I'd rather import keys. I've already imported the obvious branches, but some apps are still complaining, so they must be looking for more obscure keys. I can't just import whole branches because XP doesn't like it, and fair enough since some of them cover system internals.)