Note that by simple factoring any condition of the form A*f(x,y) - B*f(x,y) = 0 (where A and B are arbitrary constants) simplifies to f(x,y) = 0. Your last four conditions are of this form. So the constants are playing no role in the conditions. This is consistent with Tom Leslie's finding.

Once you correct that problem, I think that you want two of those D[2]s to be D[1].

@awass 

I'd rather use the quotes once---inside the procedure---than need to use quotes every time that I invoke the procedure; so I don't consider your alternative a simplification.

A numeric is manifestly a rational number: an integer, fraction, or float. A realcons is something that would become numeric if evalf were applied to it. In the case at hand, it wouldn't matter if you used realcons instead of numeric because evalf is used inside the procedure. Types have help pages: See ?type,numeric and ?type,realcons.

A bound variable with a common name like t that isn't declared local is a dangerous and foolish thing. If you were to assign a value to t for some unrelated reason, then your procedure would stop working. Maple makes an exception for the bound variables in seq, add, and mul. These are given some special protected status that's almost as good as being local.

I'm not a Groebner user, but randpoly is my go-to for constructing examples.

@mskalsi You need to freeze & thaw the g(u[x]):

thaw([coeffs(subs(g(u[x])= freeze(g(u[x])), %), du)]);

This can also be done by frontend:

frontend(coeffs, [%], [{`+`, `*`}, {}], du);

@9009134 I agree with Preben. In this case, it's difficult or impossible the remove the RootOfs before numeric values are substituted for the parameters.

@9009134 The option explicit means something different when used with a dsolve command than with a solve command. For dsolve, use implicit.

What makes you think that the result is close to 12.319?

@Mac Dude Surely I am neither saying that all Indians are spammers nor that all spam comes from India!

There is no need to look at any logs or ferret out anything. That would be a waste of time. There is nothing special about MaplePrimes. Any message board on the Internet which doesn't block spam will be flooded by it. Spammers are not trying to target MaplePrimes users, or to sell them anything, or to advertise to them. It's all about Search Engine Optimization (SEO). The techniques for blocking spam on message boards are well known; they just need to be implemented here.

@Preben Alsholm And those 31 are what you saw immediately after I had spent 10 minutes continuously deleting. I gave up when I saw that it was going to take me much longer to finish.

If you had the option to bulk delete, as I described, and obvious titles that are URLs were automatically deleted, would you then delete the spam?

@taro Oh, I was confused. I thought that you were asking for the ability to delete messages that are not spam. Yes, I agree that the reputation requirement for the ability to Delete As Spam should be lowered to 100.

It is a complete waste of time for you or anyone else to "report" spam. To those who have the ability to delete spam, the presence of spam is totally obvious; they have no need to be told via a "report" that a message is spam.

The option to report messages as spam should be removed so that these users don't waste their time doing it.

@taro Yes, there is another reason for it. As I explained elsewhere in this thread, there is a distinction between convert(x, string) and `convert/string`(x), only when x is a symbol. The distinction is whether the procedure `convert/string` gets called. The final result is only different when x is a symbol necessarily enclosed in backquotes; it will not be different when x is unnecessarily enclosed in backquotes.

n.d is not a symbol. It contains a special character (.), yet it is not enclosed in backquotes, therefore it's not a symbol. Indeed, n.d is the noncommutative multiplication of n and d.

@sand15 There is no synctactic equivalence between cmd1(..., subcmdA) and `cmd1/subcmdA`(...). However, there is a convention that for several older commands cmd1, that if the action of of cmd1(..., subcmdA) is mediated by a procedure, then that procedure's name is `cmd1/subcmdA`.When this is true for a particular command cmd1, that will be stated on the command's help page. This convention does indeed apply to convert, and there is a procedure named `convert/string`. The case convert(symbol, string) is very special: It is handled by the kernel rather than by that procedure. This surprised even me.

Nothing in the above paragraph is about tilde or map. There is a syntactic equivalence between map(x-> f(x, B), L) and map(f, L, B), (and the latter is more efficient). There is also a syntactic equivalence between map(f, L) and f~(L). Your error was conflating these two equivalences, making it appear as if the distinction was between tilde and map.

@taro Deleting a post which is not spam is a very rare and rarely needed operation. Why should more people have that power?

@taro Your symbol `N.D` contains a nonstandard character, the period, and so it must be enclosed in backquotes to be considered a symbol. On the other hand, Norman is a symbol already, so enclosing it in backquotes is redundant. In either case, the string result given can be parsed to recover the original symbol. See ?symbol.

@vv My first attempt at this would also have been string based. Because of the massive machinery of computer algebra at our disposal, I have a vague sense that there's an easier or better way. On the other hand, this is ultimately about the simplification of displays rather than expressions, and displays are string based.

So, with the ability to count occurences in strings, one could do a key sort of the RootOfs, or indeed of any of the subexpressions given by indets(..., anything), to determine the best candidates for aliasing. I'm writing on my phone right now (parked in a rest area waiting out a thunderstorm) without access to a computer with Maple.