Here's the problem: I've looked at 34 AI cities. Of those, 30 have changed demands since I first looked, and 2 of the remaining 4 now have demands in (parens). The remaining two have never received a caravan from me. Statistically, it would appear that there are NO cities with this property among the AI. Can this be so (in 2.42?)

Meanwhile, my capital seems to have this property, so I'm making out like a bandit locally, but enduring the usual PITA of having caravans arrive at cities that no longer want my cargoes (or more annoying, a galleon arrives with two cargos for (say) Moscow, and delivery of the first cancels the demand for the second. We all know how bad the trade interface is, and this just makes it more so.

Three points to mention here.

First, how long has it been since you first looked at the AI cities? There are global factors in the game which change the commodites available (eg, industrializaiton makes cities supply oil), so the same commodities do not repeat indefinitely.

Second, in part because commodities do change, and in part because big science bonuses can get wasted, it is better to have lower payoff routes that you can complete consistently every one or two or three turns, rather than a huge payoff route that you can complete every 15 turns or so.

Third, even if some of the cities have a commodity or two in parens, all is not lost. Try sending pair of caravans to such cities, one with a commodity that is in parens and one with a commodity that is demanded but is not in parens. You can usually make the parens flip from one commodity to the other and back again, making a repeated commodity city out of one that has parens.

I hope this helps. Get out there and go trading.

Understood. It seems like they changed on a short time frame, but in fact I didn't note the year when I first checked (it was around the time I got MPE in Caravel times; I'm up to Galleons now. Looking at patterns, it seems like certain cities get Dye or Hides as every 4th or 5th demand.

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Second, in part because commodities do change, and in part because big science bonuses can get wasted, it is better to have lower payoff routes that you can complete consistently every one or two or three turns, rather than a huge payoff route that you can complete every 15 turns or so.
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Part of the problem is the large map. It takes many, many turns for a caravan to reach an AI city. The exception has been Japan, but they are on the same continent (not that I can reach them overland). Still, I have three "+10" routes from my capital to Kyoto. The Vikings are also on the same continent, and sneak attack too often for profitable trading. Of course, now I'm poised to settle *their* bacon, but that's a digression from trade. Fun, though. The nearest AI not on my continent is the Sioux. Most of their cities are only four or five turns from my capital by galleon and overland. (You'd think these AI know about ironclads! Damned few coastal cities!) The nearest Greek cities are 6 or 7 turns out (three from the end of my land mass, so once railroads are in, they'll be 3 turns from my capital). The Russians are 2 or 3 turns farther away (8-10) and the Spanish are beyond that, just about exactly around the world...which puts them right across the water from "Alaska" one of my major colonies. So I will try to have "Alaska" trade with the Spanish and Russians while the homeland trades with the Sioux and the Greeks. Maybe the heartland with the Sioux and the west with the Greeks and Russians.

As for big science payoffs, I'm getting tech every two turns *without* trade, thanks to the SSC at the heart of my ICS. So I'm not exactly hurting. I just didn't feel like I understood "repeated commodities."

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Third, even if some of the cities have a commodity or two in parens, all is not lost. Try sending pair of caravans to such cities, one with a commodity that is in parens and one with a commodity that is demanded but is not in parens. You can usually make the parens flip from one commodity to the other and back again, making a repeated commodity city out of one that has parens.
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Aha! I'll try that, with concentration on the Sioux and the Greeks (and Spain from Alaska).

Thanks for the help!

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Scouse Git[1]

quote: Originally posted by Adam Smith on 03-08-2001 07:21 PM Third, even if some of the cities have a commodity or two in parens, all is not lost. Try sending pair of caravans to such cities, one with a commodity that is in parens and one with a commodity that is demanded but is not in parens. You can usually make the parens flip from one commodity to the other and back again, making a repeated commodity city out of one that has parens.

Generally, the new trade route needs to be more valuable than the old ones for that to happen (the city must already have 3 trade routes, and it will re-calculate supply and demand when a new trade route comes and replaces one of the 3). In two continental trading, I have full control over the trade routes, thus I can blow up the parens of any particular supply and demand of a city. I lower the city's existing trade routes' values by hiring all of the city's trading partner cities' citizens as specialists (temporarily, they can come back to work after the trading in the same turn). Then I send a couple of caravans from non-partner cities to that city, making sure that the non-partner cities do not demand or supply the particular commodity I want to deal with. The new trade routes will almost surely be established and the supply and demand for the city will be renewed. You can also do it to a foreign city, as far as you keep a record on which cities have generated the trade routes.

I don't fully understand trade routes, but you postulate something I had suspected.

If a destination city (say City A) has three trade routes and you send in a new caravan to try and set up a fourth route, that the fourth route will bump off and replace one of City A's current three if and only if that new trade route would generate more permanent trade arrows per turn. A city only get permanent trade arrows from its three best routes. I think everyone agrees with this.

Then you say something that I've been too lazy to prove. You imply that if City A has one of its demands in parentheses, the reason is that that demand is being met by one of its permanent trade routes. You're saying that supplies and demands being tied up are not mysterious - but are always associated with a given city's three permanent trade routes.

This leads to the breakthrough that if a new trade route would give more permanent trade arrows than City A's worst permanent route, it bumps off the worst route which then releases a tied up demand if (and only if) that worst route was meeting a demand.

Now - and here's your sheerly brilliant step - you realize that you yourself can artificially determine the "value" (as seen by the game in terms of permanent arrows at the instant the new caravan arrives) of City A's trade routes by cleverly shifting workers on or off of trade squares in cities that City A has permanent routes with. With this "power" you can force an old demand-meeting route to be replaced by the new one (demand-meeting or not). Voila! That Babylonian capital is again demanding Gold from your Super Science City! Or perhaps the one and only AI demanding Copper is again open for business! Well, I guess you only have total control, as you note, over your own cities - but this is still good. This could really change trading (for those who don't mind a little micromanagement and record keeping).

quote: Originally posted by Adam Smith on 03-09-2001 02:11 PM I am not sure that the new trade route has to be more valuable than the old one, and I know that the destination city does not have to have three trade routes to make this work. Suppose the destination city reads Silver, Wine, (Cloth) Send a cloth and a wine caravan. Land the wine first and the destination city reads Silver, (Wine), Cloth Then land the cloth caravan and it reads Silver, Wine, (Cloth) again. This does not work for every city, but it happens often enough to turn a tidy profit. And, unlike the Two Continents Strategy, you do not have to travel half way around the world to turn a profit.

Perhaps in your example the city (City A) DID have 3 routes. It's just that two of its best routes were routes that IT established (and therefore are tying up two of its supplies which generally can't be seen for an opponent's city).

Your new Wine route comes in and is better than City A's worst route - the one where it's getting Cloth. Now City A's three best routes are 1. Wine from you to City A; 2. something from City A to some other city; 3. yet another thing from city A to some other city. The demanded Wine and two of City A's supplies are in parentheses, but Cloth is now an unmet demand. (Note that City A didn't even need to be demanding Wine to free up the Cloth route. Any caravan coming in that would give City A more permanent trade arrows than the Cloth route was giving would have bumped the Cloth route out of the top three - thus freeing it up as a demand.)

Now your new Cloth caravan comes in. It's better than the your recent Wine route. Now City A's three best routes are 1. Cloth from you to City A; 2. something from City A to some other city; 3. yet another thing from city A to some other city. The demanded Cloth and two of City A's supplies are in parentheses, but Wine is now an unmet demand again.

Next time you deliver a caravan to City A, implement Xin Yu's strategy by moving all your workers in your city supplying Cloth off of their trade squares. Your new caravan is going to look pretty good to City A. So good in fact that City A will ditch that "terrible" Cloth route in favor of your new route. Voila! City A wants Cloth again. Now reassign workers in your Cloth supplying city and get that next caravan ready!

You're right. Three delivered caravans (each with a different demanded commodity) not tying up any demands in destination City A sounds unlikely under this theory. The only way for it to happen is if City A made three routes early on. All three of its best routes are ones in which it is doing the supplying. Apparently your three caravans weren't good enough to knock out any of City A's three permanent routes.

Maybe the commodities are 'paired'? Hide is paired with Uranium, for example. When a supply/demand is tied up, the computer searches for the commodity's buddy and frees that commodity up. At the beginning, since Uranium is not available, Hide is sometimes paired with itself, and will be permanently available.

Is it time to cheat up a world with evenly spread cities and test demand across time? I'd suspect that some patterns could be found:

1. predictable time of demand change (game year, population threshold, or tech)
2. weighted importance of commodities in different conditions

Many posters grumble about the demand vanishing just before delivery. If we know how many turns to expect demand to remain, or where it might shift next, planning deliveries could be made less stressful. And more profitable.

Trying to exhaustively account for just these 3 variables would give me a headache. However, I'd be willing to test out a generic map with uniform cities to start. Is there any interest in this info?