The trade O-P did was perfect in its own right. But that isn't all that is important. Also important is the thought behind it. For instance; was the timing right ?? I think it was. Both Russia and Japan had monopoly techs the other lacks and we also had those. And Russia and Japan couldn't have met (
WHY NOT ??? 
), so we could sell at monopoly prices to both.
But O-P chose to not obtain all techs. We still lack Ceremonial burial. I am curious why O-P chose that path.
O-P's trade sequence 2510BC:
- 1: Japan: wheel <-> Carthago: masonry + 67g.
- 2: russia: warrior code + pottery <-> Carthago: wheel + 59g.
- 3: japan: 44g <-> Carthago: warrior code.
japan received: masonry + warrior code + 67g
russia received: wheel + 59g
Carthago received: wheel +warrior code + pottery +44g
japan gave: wheel +44g
russia gave: warrior code + pottery
Carthago gave: masonry + 67g + 59g
japan balance: +2tech + 23g
russia balance: +1tech + 59g
Carthago balance: +3tech - 82g
Rik's Alternative:
- 1: Japan: Wheel+Bronze+Pottery + 8 gold <-> Carthago: Alphabet + Masonry.
- 2: Russia: Warrior Code + Ceremonial burial + 10 gold <-> Carthago: Alphabet + The Wheel.
- 3: Japan: 27 gold <-> Carthago: Warrior Code.
Japan received: Alphabet + Masonry + Warrior Code
Russia received: Alphabet + The Wheel
Carthago received: Wheel + Warrior Code + Pottery + Ceremonial burial + 45 gold.
japan gave: wheel + bronze + pottery +35 gold.
russia gave: warrior code + ceremonial burial +10 gold
Carthago gave: Masonry + Alphabet
Japan balance: +3 tech -35 gold.
Russia balance: +2 tech -10 gold.
Carthago balance: +4 tech +45 gold.
The difference is that we have "sold" alphabet to both for a total of Ceremonial burial + 101 gold. The question is "is this smart?".
I think it is for several reasons. First is that perhaps Japan or Russia had techs that were still invisible to us (Iron Working or writing, for instance). We would have had a chance to obtain those as well then. Also; having more techs gives us a better position to trade with new civs we'll meet.
The cost of giving up on Alphabet is not so big. You first have to realise why would someone not want to trade it ? The answer is to keep a shot at researching Philosophy (1 free tech) or Literature (great library) first. In our variant that is not possible, so this is no disadvantage.
Also; withholding techs has a risk; they might research it themselves or meet someone who has alphabet and trade it with them, which means: no return on investment for us.
It has an added risk; we've given them now curraghs, so they will meet new civs quicker. To negate this downside we are now forced to build a few more curraghs, to stay ahead in sea-exploration.
But in the end; it is a matter of taste. O-P's trades were maxxed out for gold etc. I would have included Alphabet in this setup. Good trades, nonetheless!!
