Originally Posted by brunos

This has nothing to do with Amadeus.

Big airlines have their own yield management system. They have history of all flight searches. They know which flight you searched in the past (by FFP number and possibly IP).Some even send emails a day later to suggest you complete your booking, eventhough I only looked at the flight and its fare.

The issue is whether that affects the airline yield management and fare availability. It is not only fare bucket, but also fare basis availability within a fare bucket.
Yield management systems have got extremely sophisticated at some airlines, and are a best-guarded secret. Hence, there will be no "proof".
But my personal experience, and that of some friends, is that if you search repeatedly for a flight and its price, its fare increases. And that is different from the "hold" function that you properly describe.
I don't wish to detail here, but I am fully convinced about AF and their domestic flights.

I understand that this is no "proof" and that there are believers on both side.