Greetings!!
After some digging i found out in metaversedata/english/techtree.xml all the tech info including cost to research and this aivalue which i guess is how much the ai consider a particular ai 'worth' for an exchange.
Well let just say this aivalue , very differently from other strategy game like civ4, has absolutely no connection to how much research points are needed.
For instance picking someone at random
Some very early tech like
New Propulsion Techniques -> Cost 25 -> AiValue 25
Beam Weapon theory -> 100 -> 10
PlanetaryImprovements -> 100 -> 15
MiniBalls ->75 -> 10
Now let's check out still at random some middlegame tech
Expert Diplomacy -> 500 -> 1
Xeno Business -> 400 -> 3
Cultural Conquest -> 2000 -> 3
Xeno Farm Construction III -> 8000 -> 3
Habitat Improvement -> 1550 -> 15
Terraforming -> 2050 -> NOVALUE (BUG?)
Ultimate Miniaturization -> 8400 -> 5
Kanvium III -> 900 -> 3
Graviton Driver IV -> 2600 -> 8
Now i *HOPE* the true value of a tech for an ai is the real value * aivalue (graviton driver4 = 2600*8 = 20800)
Otherwhise if it's only the aivalue i'm a little disconcerned about this system.
I of course was looking for a way to avoid tech pooling from the ai which, imho , totally spoils the game.
If someone has time and patiance to test this out and possibly mod a way to reduce drastically ai tech trading please let me know ( i don't care if i can't trade either fine with me)
Hope this help understand game mechanics better!
