heres an interesting bit of AI diplomacy: I tried to trade something of mine for harpoon, the computer says 'no way, get lost'.
But when i tried to trade the same thing for harpoon, harpoon II, miniballs and a bit of money, it says yes!

both offers initiated by me, without having exited the diplo screen or completed any other trade inbetween.

I've also noticed a similar thing with plasma and plasma II. (will see if it happens further up the tree as I play!)

I guess this could be because the tech starting a 'new' segment of the weapon tree is more expensive than the few after, so as (for example) harpoon II costs less to research than harpoon, it is willing to trade that, and then as harpoon is redundant it doesnt mind you adding it as well. Has anyone else seen this sort of crazy trading?

maybe the AI could value a tech at max(techs value, values of all prerequisite techs other party hasnt got) or something like? this would stop the AI making this sort of unfavourable trade for itself.

Mark