I don't typically trade techs with the AI very much, and I think this is a weak point in my game. From browsing around the forums, it appears Education, Philosophy, and perhaps Aesthetics have good trade/bribe value with the AI. Are there others I should know about? I'd also like to know more about what determines an AI's willingness to trade a tech to me. What determines which techs they're willing to part with? And what determines how much they want in return for a tech?