He offers archery and 480g on "what will you give me for this"; needless to say I don't want archery for wfybta reasons, yet plain 480g don't work...

since when does archery have negative value(not that I don't agree with him tbh :p)

When you ask what will you give me for this he gives you maximum possible he wants to give, when there is already something on the table he adds other stuff. In this case he obviously felt that archery + 480 gold was ok, obviosly 480g vs litterature is also ok... This is just how the AI works, and doesn't have anything to do with wyftba...

I know it doesn't, just found it fun :p

anyway, maths would say archery is -4 ;)

Are you sure you didn't have any combat betweeen these screenies?

same turn everything; settled on whatever he wanted to give, since I already sold it to everyone and... any penny is good, especially since I already completed the wonder...

?! strange, never saw this one. You must be right archery's worth -4 :lol:.

Seriously though, sometimes when i have finished a tech and switch to another i get notified that i have researched archery (or hunting or whatever small tech) without ever having clicked on it so there may be some small rounding bug somewhere in the code (or maybe it isn't a bug and i just don't understand the overflow fully here) that handles research overflow in such a way that it sees archery as more than researched though you don't have it.

Example where i'll try to explain what might happen.

It's clear that comp is ready to pay you 476 gold for lit, not 480

If this is right something like this might be the case:

suppose archery's 100 beakers and you have researched nothing,
In this case the comps might say (counting a beaker as a gold for simplicity) :
i offer (100-0) beakers + 376 gold for lit

suppose archery's 100 beakers and you have researched half (50 beakers),
In this case the comps says :
i offer (100 -50) beakers + 426 gold for lit

and suppose now that you've researched archery + overflow of 4 = 104 beakers In this case the comps might think :
i offer (100 - 104) beakers + 480 gold for lit, it offers more since it counts negative beakers on archery and is able to offer you more gold.

If all this is true then the weird phenomenon i'm experiencing sometimes is in line with your experience here. But i know there's a lot of speculation here and there might be a much simpler explanation.

it's marathon... it'd be a while till I'd research archery in 1 turn ;)

probably it's just a different mechanic for the trades; I knew "what would make this work" is the way to get max. However, I thought that max. is also achievable by normal trade, which apparently isn't.