Slitherine

I'm a bit mystified about how bargain points work. They seem to be a kind of meta-currency to put a value on things.

I assume these points are weighted by the need of the recipient - e.g. if I offer metal and they drown in it I would get less bargain points than if they had no metal.

Lets assume a trade where both sides offer the same amount of bargain points. One could assume that both parties should be happy with the trade. But lets add greed and say an equal amount of BPs would give a 50% chance.
Well, not so. I offer 11, they offer 8 and the chance is 11% - ?

What is the math behind this?

That's the essence of things indeed. Relative interest, greed, appraisal of the context ... For the details of all calculations involved, I regret to write it can't be summarised really, you would need to read the code.

Hmm, but then I seem to have always offered shitty deals.

So bargain points represent the value of something - correct? So when I offer something of equal value and the other side wants what I have to offer there should be a high percentage for the deal. OTOH if they don't want it - low percentage.

Example:
1 bottle of water costs 1 gold at Cleos supermarket in Alexandria.
1 scroll of enlightment costs 10.

Example- meeting a thirsty man in the Sahara:
An offer of 1 gold for the water - 100%
10 gold - 50% (if he has the money and is really thirsty)
100 gold - 100% (if he is dieing of thirst)
But:
10 gold for the scroll - 10% (no current use)
20 gold - 0%
1 gold - 30% (if he is rich and not very thirsty)
1 gold - 0% (if he is very thirsty or poor)


At some point in the game I should have offered soething that the other side is mildly interested in. But I have never seen a 100% chance (or anything near it) for an on par deal in BPs I ever offered.
So I have either totally misjudged my customers or what is going on here?