[hyperpallium]

backrub/pagerank is a specific kind of link-based search ranking. Link-based ranking was well-know before e.g. citation count. Was Robin Li's the same kind?

What were the "several times" backrub had been implemented before?

A "mining application" is a very general concept, and does not imply a specific algorithm.

I was not assuming but requesting information; and not "again" but once.

FWIW I'm intrigued by the school of thought that Google's success was largely due to just giving people what they want. Instead of crowded portals, just search, fast search, and search that's relevant. When I tested it at the time, I found competing search pretty similar for relevance. But google was faster.

[hyperpallium]

Too late to edit, but I'd forgotten paid-placement was a thing in search results before google. Can you believe it?

Of course, adwords has similarities (and copied from overture/goto), but don't masquerade as search results (though becoming less distinguishable over time...).