[andrewla]

This is not true. A (bad) heuristic for search results might be "rank the documents by the total number of occurrences of each search term in that document".

That's not an algorithm -- that's a desired result. Similar to how "sorting a list" is a description of a class of algorithms; it gives no description of how a machine can accomplish that goal.

The difference between the heuristic above and "sort a list" is that the success criteria of the latter can be very well defined, whereas the heuristic presented is an attempt at approximating the desired result, which is something like "present the best search results first, for some meaning of best".

[noxToken]

>"rank the documents by the total number of occurrences of each search term in that document"

I fail to see how this is not an algorithm. The heuristic (rank search results from most to least relevant) is backed by an algorithm (find occurrence of word, sort document based on occurrences). I like to approximate the two by thinking of heuristics as an approach to solving a given problem while algorithms are actions to taken to get to the end results.

[PeterisP]

There's an algorithm to rank the documents by an arbitrary metric. And there's an algorithm to calculate the number of occurrences of each search term in that document.

However, those are insignificant implementation details - all the logic (and all the good and bad results) comes from the arbitrary decision to use the number of occurrences as meaningful for measuring the relevance, from the choice of heuristic.

[Retra]

That's just saying it's the wrong algorithm, not that it isn't an algorithm. Every computation of pi has truncated the result, which is a 'heuristic' decision, but that doesn't invalidate the fact that pi is computed using an algorithm.

All algorithms approximate things, after all. That's simply a consequence of abstraction.