What about Research?

[anarres]

The cost of a tech drops when someone else knows it.

With 1 human player you can work out which techs they have, out of the ones you are able to research (by checking the cost in F1).

This can get a little tricky if you are also researching something else, because you can only set the F1 science rate, then switch to F6 and look at the # of turns for that tech rate. You then go back to F1 (without having changed your research), change the tech rate, then go back to F6 to see the # of turns.

Eventually you get the approximate cost, which tells you how many others know it.

Use GreyFox's techcalc (from CFC utilities) to see what the costs are for different numbers of players.

P.S. Don't forget that any scientists are not included in the F1 "science" spending totals, so if you have 2 scientists that's an extra 6 beakers per turn you have to take in to account.