Forum Moderators: Robert Charlton & goodroi
Any rate, yes Google has some very sophistated semantic components in their algorithm, and they are growing more so all the time. You won't find anything like a one-to-one mapping from what I can see, although on some searches it may seem like that. But that's my point -- semantic mapping appears to be search specific. The "holy grail" of search seems to be user intention, and semantics is one tool in that quest.
On-page factors can play a part, and backlink influence (including words near the backlink). Google has given us the "tilde" operator [~].Put it in front of a keyword when you search, and you will see at least the top "layer" of semantic matching.
[edited by: tedster at 1:27 am (utc) on Dec. 11, 2006]
And, even if you get it down to a very precise singluar vs plural term, the meaning can be quite different than just singluar vs plural. EG: "blue balls".
In terms of key word / phrase promotion, I'd go for what is used most commonly in the business and by customers (if it can be determined). And, hedging of bets would say don't place all of your eggs in one basket!
Also, I don't think G handles singular vs plural consistenly in different areas (e.g. strict search vs use of AdWords).