A pattern governing supply and demand changes

[solo]

samson,

I also believe terrain is a key and can also explain the lack of action in certain commodities, but perhaps the era, the continent, and maybe even the particular civ involved when a city is founded, may have some influence, too, on these lists.

I am continuing my hotseat game, to investigate further the interaction of the 16 turn cycle with actively trading cities. One thing I keep track of is the frequency of commodities on the lists of cities, so I will be able to correlate these to the types on terrain found in each city in my game. I will also record any terraforming that is performed. Do you think each road, and its location should be noted? I have not been doing this so far, but can re-construct that information from saves. I kind of doubt adding a road would enable a city, but in this game you never know, because roads ARE tied to trade in other significant ways.

I have attached another MGE hotseat save in another post that may be useful for studying terrain effects on these supply and demand lists when founding cities.

I have also given some thought to your earlier question about whether the 16 turn cycle is a trigger or a cause, and my conclusions are that they definitely act as a trigger. If there were not any gaps in the pattern, I would also have to conclude that the cycle is a cause, in addition to being a trigger. Perhaps other factors, such as city size, knowledge of trade, map trades, or just contact among civs act as causes to enable particular cities, with changes triggered on a regular basis, if a city is enabled, every 16 turns. Sound reasonable?

[William Keenan]

Originally posted by samson
I confirm SG's observation. Oil is available as a supply commodity from the start, often found occuring cities with the oil resource or having a large number of desert squares.

In fact, I believe that commodities which have a corresponding resource (Gold, Silk, Spice, Oil, Coal, Wine and Gems) are frequently supplied by cities built near that resource.

Originally posted by Scouse Gits


Sorry...but that is incorrect. In a recent game I had an oil supply in one city with the discovery of trade...circa 2700BC !

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SG(2)

My great respect for you gentlemen has just been shaken. I would not have expected either of you to contradict solidly founded research without rigorously testing first.

[solo]

William,

For sure, rigorous testing is the best way to obtain reliable information, but sometimes exceptions to rules surmised from such tests are found, too! Getting oil as a supply earlier than Industrialization may be an example of this, an exception found to a rule deduced from many tests.

Another example: for a long time most players shared some misconceptions about the rules governing the appearances of nomads from huts.

Not too many people bother with systematic tests, but many still offer some excellent general observations gleaned from their vast experience just playing the game. Even when faulty observations are made and corrected, this is also a service to all players, because something new might be learned.

So with that thought in mind, I present a new observation which has not been rigorously tested yet, because it is something novel that happened in my test game that I think might be of great interest now to others investigating the re-supply problem. Time will tell whether this new idea becomes a useful and reliable technique.


Building commodity caravans on cycle turns may result in a free supply

After resuming my test game, I happened to finish a caravan in Washington on the same turn it was eligible for a change of supply via the 16 turn cycle. Before this turn, Washington showed:

Supplies: hides, silk, salt
Demands: dye, beads, wine

However, as the American's turn began, I was given the following commodity choices for my new caravan:

hides, silk, dye

I chose dye, and after all cities were processed, went into Washington's city screen and observed:

Supplies: hides, silk, salt
Demands: dye, copper, wine

Since dye did not appear on the supply list, I was able to build a dye caravan without blocking a supply! Normally, commodities other than hides are blocked when being built!

It appears that timing caravan builds to coincide with a city's 16 turn cycle turns, may allow a player to get more commodities than are usually possible from a city before all three supplies become blocked.

Previously, only low-paying hides could be built without blocking a supply at this stage in the game, before trade route manipulations come into play. Obtaining extra higher-paying commodities early, without blocking a supply, would be a plus.

By the way, I went back to replay this turn, choosing silk instead of dye for the build, but silk ended up remaining on the list and became blocked. So, for now I will assume this probably only works if you observe a commodity that is new to the supply list, when asked to make your choice.

As I continue my game, I will be trying this some more to see how often this little exploit works.

[Scouse Gits]

Originally posted by William Keenan My great respect for you gentlemen has just been shaken. I would not have expected either of you to contradict solidly founded research without rigorously testing first.

William...you beg the question...what is solidly founded research?

I have just been back to the game I mentioned above and half of my 6 cities supply Oil! The year is 2750BC playing in 2.42 on a large world.

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SG(2)

[samson]

William -

A single counter-example can easily refute the most 'solid' reseach.

Both SG and I offered ones to Solo's claim that cities never supply and demand the same quantity. I even posted a screenshot.

Your comment makes no sense to me.

[solo]

Perhaps William was basing that observation about oil on a comment made by one of us, back in the days when he had trust in what we say.

To me it's no big deal. I know that if I slip and state something that is not quite true, others will notice immediately and will set the record straight before any false statement gains credence. It helps me to learn from when I am being wrong, too.

The main thing and enjoyment comes from the cooperative investigations into various topics related to the game, where the collective wisdom always prevails, and many times a statement or claim, proven false by the "exception to the rule", still has validity if only it had been presented in a more precise way. For example, my statement that a commodity can not be found on supply and demand lists at the same time was proven false, but with a few exceptions, you can almost always count on this to happen.

I must apologize for my imprecise wording in that case, but am afraid I will continue to make a lot of mistakes in my future observations in the desire and enthusiam to share information. Sometimes I'll get it right on the first try!

[samson]

Solo -

Re: Building commodity caravans on cycle turns may result in a free supply.

I think something unusual happened in the case you site. The supply list changed temporarily and then changed back. I tested your idea in several saved games where a city was about to change supply on the 16-turn cycle. In none of those cases did the supply list alter twice. Perhaps, Dye is a special case.

In general, I think, it is more advisable to build caravans on the turn before a change is expected, if at least one supply commodity is still available.

On another matter, restoring an old game save I came across a case where two cities, Washington and New York were about to undergo 16-cycle changes in a few turns. At the point of the save, I had 9 techs and was researching the 10th. If I set the science rate to 0, the cities change as follows on their respective turns:

New York

Supply: Wine, Salt, Silk ==> Wine, Salt, Silk
Demand: Dye, Hides, Beads ==> Hides, Beads, Cloth

Washington

Supply: Gold, Silver, Wool ==> Gold, Silver, Copper
Demand: Dye, Hides, Beads ==> Hides, Beads, Cloth

However, if I set the research rate high and acquire a 10th tech before the cities change (or if I trade for a 10th tech -- what the tech is doesn't matter) the cities change to:

New York:

Supply ==> Hides, Salt, Gold
Demand ==> Beads, Cloth, Silver

Washington:

Supply ==> Hides, Silver, Dye
Demand ==> Beads, Cloth, Wool

All other events of the replay were the same.

I also tried trading for multiple techs and found that 10, 11, or 12 techs all produced the same result. The key seems to be crossing the 10-tech boundary.


As to the question of cause/trigger for the 16-turn cycle, I'm still neutral. The presence of gaps in the pattern doesn't rule out the cycle as a cause, it just means there may be other factors that aren't understood. Perhaps # of techs is one.

I tried another experiment using a Trade-start in which I built 16 cities while setting the science rate to 0. After letting the game run down to 1 AD, I checked supply/demand in all cities against their starting values. No changes in any cities! It would seem that supply/demand changes are tied to the acquistion of techs in some way.

Finally, if you still have the information ... could you repost your 16-cycle chart showing the nature of 'X' change. For example, a "D" for demand-only change, a "S" for supply-only change, a "B" for both. Thanks.

[solo]

Samson, here is the list, which now includes 5 more turns.

It is coded as follows:

O – No change on this turn
S – Change(s) to the supply list only (only two occurrences!)
D – Change(s) to the demand list only
B – Change(s) to both lists
C – Changes in demand list occurred the turn a caravan was delivered to Cumae
? – Demand change, unsure of supply since this was the turn trade was discovered
F – Turn Akkad and following cities were founded

Note: The demand changes for Hamburg and Thermopylae did not include any new entries on their demand lists. Rather, two commodities on these switched places.

The first turn is 2250 BC and the last one is 975 BC.

OOOOOOOOOOOOSOOOOOOOOOOOOOO Delhi
OOOOOOOOOOODOOOOOOOOOOOOOOO Berlin
OOOOOOOOOOBOOOOOOOOOOOOOOOO Leipzig
OOOOOOOOODOOOOOOOOOOOOOOODO Rome
OOOOOOOOBOOOOOOOOOOOOOOODOO Washington
OOOOOOOOOOOOOOOOOOOOOOODOOO Athens
OOOOOOOOOOOOOOOOOOOOOODOOOO Thebes
OOOOOOOOOOOOOOOOOOOOOBOOOOO Memphis
OOOOBOOOOOOOOOOOOOOOSOOOOOO New York
OOOBOOOOOOOOOOOOOOOBOOOOOOO Babylon
OOBOOOOOOOOOOOOOOOBOOOOOOOO Bombay
ODOOOOOOOOOOOOOOODOOOOOOOOO Veii
OOOOOOOOOOOOOOOOOOOOOOOOOOO Sparta
OOOOOOOOOOOOOOOOOOOOOOOOOOO Ur
OOOOOOOOOOOOOOBOOOOOOOOOOOO Nineveh
OOOOOOOOOOOOODOOOOOOOOOOOOO Ashur
OOOOOOOOOOOODOOOOOOOOOOOOOO Hamburg
OOOOOOOOOOOOOOOOOOOOOOOOOOO Heliopolis
OOOOOOOOOOOOOOOOOOOOOOOOOOD Thermopylae
OOOOOOOOODOOOOOOOOOOOOOOOOO Madras
OOOOOOOOBOOOOOOOOOOOOOOOOOO Ellipi
OOOOOOODOOOOOOOOOOOOOOODOOO Boston
OOOOOOBOOOOOOOOOOOOOOOOOOOO Antium
OOOOODOOOOOOOOOOOOOOOOOOOOO Konigsberg
OOOODOOOOOOOOOOOOOOOOOOOOOO Elephantine
OOODOOOOOOOOOOOOOOOBOOOOOOO Bangalore
OOBOOOOOOOOOOOOOOOOOOOOOOOO Corinth
OBOOOOOOOOOOOOOOOOOOOOOOOOO Frankfurt
?OOOOOOOOOOOOOOOBOOOOOOOOOO Alexandria
OOOOOOOOOOOOOOOOOOOOOOOOOOO Delphi
OOOOFOOOOOOOOOBOOOOOOOOOOOO Akkad
OOOOOFOOOOOOOBOOOOOOOOOOOOO Pi-Rameses
OOOOOOOFOOOOBOOOOOOOOOOOOOO Calcutta
OOOOOOOOOFODOOOOOOOOOOOOOOO Uruk
OOOOOOOOOOFOOOOOOOOOOOOOOOO Pharsalos
OOOOOOOOOOOOOFOOOOOOOOCOOOO Cumae
OOOOOOOOOOOOOOFOOOOOOOOOBOO Philadelphia
OOOOOOOOOOOOOOOOFOOOOOODOOO Knossus
OOOOOOOOOOOOOOOOOOOFOOBOOOO Munich
OOOOOOOOOOOOOOOOOOOFOBOOOOO Argos
OOOOOOOOOOOOOOOOOOOOFOOOOOO Neapolis
OOOOOOOOOOOOOOOOOOOOOOOOOOF Heidelberg

Until my last turn, 975 BC, I thought I was beginning to see a pattern emerge with the gaps, but this hope was quashed in 975, with every city refusing to follow suit. Too bad, as the pattern was starting to look pretty spiffy, and I was even thinking that it might contain a secret encoded message, recorded behind the scenes throughout the game! Had something like that had been going on it would have really left me even more impressed with the game’s design!

After further attempts, I now agree with you that building caravans to coincide with 16-cycle turns when free supplies are left may not be the best idea, since I have been unable to repeat my initial success after 3 more tries. On two attempts the choices were identical to the previous list. On one attempt, after I picked gold (not on the previous list), it became a member, but was blocked. Maybe this is a special deal that happens just once and a while with dye. However, with replays, I determined that there was no harm in trying this, since the final outcome of the lists were the same (whether they had changes or not), when caravans were not rushed to coincide with these dates.

The revised list above includes the first non 16-cycle change turn, when a caravan was delivered to Cumae. The delivery acted as a trigger, sparking the change in that city 3 turns before its 16-cycle turn. After a replay, without a caravan delivery, the same changes occurred right on cycle, the turn after Philadelphia’s change. On another replay, where delivery was made right on the 16-cycle turn, the demand changes were the same, but a different supply commodity was blocked when forming Cumae’s trade route with Babylon. In all deliveries, gems, the delivered commodity, was in demand by Cumae. So far, there have been no more deliveries yet in this game.

The dramatic differences you note when changing the research rate to zero, and other changes related to tech accumulations reflect my experience somewhat during my replay where Trade was not shared. The sharing in the original game involved a number of tech trades, some of which put some civs above the 20 tech level. There were more gaps in my chart, and differences for some changes, during the replay. As you have suspected all along, tech progress is a major player in this equation. I will go back and review this a little, to see if I can find a direct correlation of some sort. Your experiment with zero science surprised me at first, as I would have expected just one set of changes, but now it seems very logical. Do you think you could repeat this test using just a smidgeon of research, something like a beaker or two, just to see if using zero beakers is a special case?

I do not rule out the 16-cycle as a cause, either, but think this is less and less likely as we find other influencing factors. I now am suspecting that that 16-cycle is used just a trigger to throw us off, so that we do not immediately link enabling events such as tech changes, city size, etc. as the underlying causes for supply and demand changes that seemingly occurred at random times after their enabling events. I believe that the way I went about my test, by sharing Trade evenly around, made it much easier to notice the 16 turn cycle as a trigger. It certainly helps explain why some cities have a change almost immediately, while others, which are doing much better, seem to wait forever for their own.

[Scouse Gits]

Scientific advances undoubtably play a large part in commodities, but how much of this is also linked to terrain? It's interesting to note that in the test game I mentioned above 5 out of 6 cities have tundra squares within their scope...perhaps this is the cause for the early Oil supply?

As can be seen from the save Trondheim has 4 specials but later on the wheat tiles are mined to Silk...then the city starts to demand the stuff!

-----------------

SG(2)

[Scouse Gits]

When the Wheat is mined to Silk...

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SG(2)

[solo]

SG,

I have downloaded and will look at those saves. Perhaps you would like to specialize on terrain effects.

samson,

Your idea of building a caravan before supplies are all blocked has great merit, as this may allow one to grab a commodity and make use of it just before it is replaced with a new one on the list. The trick is knowing which one to build. In my brief test:

1850 Leipzig supplies hides,silver,gold
1800 I build a gold caravan
1750 Leipzig cycle turn yields hides,silver,wool

Gold, which became blocked in 1800 was swapped away right afterwards by the new supply of wool.

However, with 3 unblocked supplies, the best first choice for a build is probably silver, so it can be used to hold the first trade route, making an alternation later most likely. Next would be hides, using Xin Yu's idea of positioning hides in trade route #2, then gold would be third, just before the 16-cycle deadline. When wool comes up next, the city is really in business!

It will take me a while to compile a list of techs that I can cross-reference with gaps in the cycle, but a few spot checks do not seem to point to tech acquistion, or tech leads as the thing solely responsible for these gaps. All my civs are in Monarchy and are using the same science rate, yet the difference in the percentage of gaps among the civs varys quite a bit.I remeber

Changes per opportunities so far are:

Romans: 6/7
Babs: 7/9
Germans: 5/8
Egypts: 6/10
Amers: 7/7
Greeks: 5/13
Indians: 7/8

In my test game, using SG's start with Trade, I also remember that the Beijing (light blue civ, as are the Americans in this test MGE test game) had changes at every opportunity, and that the civ that didn't have so many was my own, the orange English, faring more like the hapless Greeks in my MGE game. I also have a strong recollection of being especially frustrated in other games where I have tried to deliver demanded cargos to the Chinese.

How about other players? Has this been your experience, too, that some civs (colors) seem to change their demands much more often than others?

Of course, after I am able to play many more turns in my test game, I will have more data to see if some really obvious percentages turn up for the different colored civs. If this happens, the gaps may be due to this.

One question I have for Samson is that while no supply or demand changes happened in the test game when science was kept at zero, how come there were changes (albeit different ones) in the other game when science was briefly set to zero? When was zero science set and for how long?

[William Keenan]

Hmmm .... seems there was some misunderstanding. I'll try to clarify. What I said was:

• Discovering Industrialization causes cities to supply oil.
• Building Superhighways causes that city to demand oil.
• Discovering Nuclear Fission causes cities to demand Uranium.

Note that I did not say or intend, "the only possible way that a city can supply oil is after the discovery of Industrialization."

Yes, occasionally, cities supply oil before the discovery of industrialization. I've seen it, we've all seen it. And it sux when it happens because nobody wants the stuff!

Is it me? Am I vague? I think of myself as concise and to the point. Suggested improvements to my prose are welcome as I'm far from the best writer in the world.

These three facts were discovered while researching tips I was writting for the SLeague.
Advance Slot Properties
Barbarian Paper

[samson]

Solo -

However, with 3 unblocked supplies, the best first choice for a build is probably silver, so it can be used to hold the first trade route, making an alternation later most likely. Next would be hides, using Xin Yu's idea of positioning hides in trade route #2, then gold would be third, just before the 16-cycle deadline. When wool comes up next, the city is really in business!

I have recently completed some research on trade routes and their effect on supply and demand. As soon as I get it written up, I'll post it. Turns out there are a couple of trading strategies that can create a self-renewing supply. Still, timing the strategy with expected changes in commodities would be valuable.

One question I have for Samson is that while no supply or demand changes happened in the test game when science was kept at zero, how come there were changes (albeit different ones) in the other game when science was briefly set to zero? When was zero science set and for how long?

In the latter case, my point was that having a different number of techs altered what the supply/demand changes were. Why this is so, I don't know. It didn't seem to be keyed to a particular tech, just the number.

I'm guessing here that the number of techs (or the crossing of a tech# boundary like a multiple of 10) is one factor used to determine what changes occur.

If it is possible for you to go back to just prior to some of those gaps in your record, you could try giving that civ enough new techs to push it past the next multiple of 10 and see if changes happen in that event.

Thanks for the revised chart, I'll study it some more.

[Scouse Gits]

Another cheap comment from the empirical seat ...

It seems, to me, almost certain that the continent number figures in the trade goods supply equation - as I am sure you have all observed, there is a strong tendancy for all the cities of a civilisation to have closely related trade commodities (both in supply and demand). Although this could, of course, be caused by a tech level effect - I feel that once off shore conquests and colonies are established there is a greater diversity of goods available ...

SG[1]

[solo]

William,

I’ve admired some of your other research, which shows a lot of work and attention to detail. Why not join us by looking into some aspect of mystery surrounding trade supply and demand lists?

SG,

I took a look at your saves. In the earlier one, I also noticed a lot of activity for copper and gems, too. This says a lot for your idea of continental distributions of certain commodities and agrees with Marquis de Sodaq’s contention that rather than individual terrain, it is the various regions of the map that control commodity distributions. I suppose an entire map will have to plotted with the supplies and demands for each potential city site to see how these various theories hold up.

Samson,

Sometimes I can be a little dense, but now I see the distinction you are making. As you suggested, it was quite easy for me to go back and use several replays to test some of the effects the accumulation of techs have on supply and demand choices. By 2200 in my test game, the Germans had the least amount of techs, 12, and the Babylonians, who precede the Germans each turn, had accumulated 20, so I conducted a few tests having the Babs donate techs to the Germans. The first test involved Berlin, and its 16-cycle turn of 1700 BC. Without any tech gifts the following occurred:

1750 supplies: hides,wool,coal demands: dye,beads,wine
1700 supplies: hides,wool,coal demands: dye,copper,beads

So I started gifting techs, 1 more each replay, until a change occurred. This happened when the German tech level went up to 15 after three tech gifts. The result was:

Supplies: wool,beads,cloth demands: dye,copper,hides

More changes accompanied the lists after techs were gifted. What I did next was vary the 3 gifts, so that a different combination of techs could be presented as the Germans reached the level of 15 techs. There were four techs to choose from: construction, seafaring, astronomy and pottery. Sure enough, there was some variation, because whenever Pottery appeared among the 3 gifts, this was always the result:

Supplies: salt,beads,coal demands: dye,copper,hides

There were some changes, but only to the supplies list. So pottery was making things come out different when it became part of the gift. Besides the number techs acquired, it appears that certain ones, such as pottery, have their own individual affects.

Well, after this I continued testing, adding one more tech each time. It would have taken forever to test all tech combinations, but for tech levels 16, 17, and 18, results seemed to be identical to what happened at level 15, including the differences caused by having or omitting pottery from the group of techs gifted. At level 19, another change occurred, and no matter what combination I tried, I got:

Supplies: hides,coal,cloth demands: dye,copper,beads

Finally, I brought the Germans up to level 20, but the changes there were the same as at level 19.

So it appears that the tech levels causing changes on the lists are not limited to increments of 10. I suspect that the increment before a change occurs is smaller, and is similar to the increment of techs gifts needed to lower research rates when using your key civ strategy. If I remember correctly, changes in required beakers come with every 3 or 4 tech gifts to the key civ.

After this I tried another test with the same two civs, but this time, I picked Leipzig as the test city and picked the turn 975 BC, where nothing happened to Leipzig’s lists, although it was a 16-cycle opportunity. In this test, no amount of combination of tech gifts had any effect. Leipzig’s lists were always the same before and after. From this test it appears that gaps can not be influenced by tech gifts, unless some other techs have special properties, too, and are among those included in the gift.


I continue to fuss about these gaps, trying to determine the exact cause. Today I fooled around some with correlating city size and the gaps, with quite promising results, only locating one or two exceptions to the assumptions being used in trying to predict them.

Remember my comment about Hamburg and Thermopylae, the only two cities just showing changes of position on the demand lists? It turns out they are the only two that reached a new size right on their 16-cycle turns. So I tried a replay, delaying Hamburg’s growth to size 3, and the result was no change at all. However, when I slowed Thermopylae’s growth to size 4, this made no difference.

I tried this some more with other cities, and was able to create some new gaps, BUT, not with every city I attempted this with. Some changed as before, and others changed, but in a different way. Well, I guess there is no simple answer, but I am encouraged by a lot of consistency I’m observing in size 3 cities, and earlier activity involving dyes.

I look forward to seeing your trade route post when it is ready.