RE: handling many matches

[Drew Adams]

> We need scoring that "learns" from what I do/did recently,
> and from my habits....
> 
> Compare with the Internet search: it almost always brings me hundreds
> of hits, but I normally find what I was after among the first dozen.

Relatively little of that power/accuracy comes
from it learning from your habits (your previous
searches etc.).  It mostly comes from back links,
i.e., how many links a URL has from other URLs.

Of course, links among web pages in turn reflect
user use patterns (including searches).  But not
just your own use patterns.

But yes, your and my search of the same words
will return different hits.  There is some input
from our individual past uses of the internet
and the search engine.

> Even more spectacularly, when I type a search phrase into the search
> box, it guesses what my search phrase will be, and the guesses are
> almost always very accurate,...  Some of the candidates are based
> on my previous search phrases, and the ones I typed are always ready 
> to be reused, with a special indication to let me know I recently
> used them.

Yes.  All of that can be food for thought for Emacs.
We already incorporate something similar with things
like dabbrev and library `completion.el'.  And even
minibuffer completion incorporates it in some cases,
promoting recent input history.

> It is this kind of powerful scoring that I think we need to develop if
> we are going to handle many dozens of completion candidates.

Yes and no.  Frequency of use and recency of use
are two (different) scoring criteria.  There are
_lots_ of different ways to score and sort.

So then you have the problem of how to tell
Emacs, in any given completion context, just
what to favor.

All of this is good to have.  And we need good
ways to choose among such possibilities,
including on the fly.