How Supply and Demand Lists Are Determined

[solo]

Working on this has been a pleasure, too.

I may have spoke too soon about kinks, as when checking Hamburg, wool presents a problem, coming on to the supply list 2 times, though its DQ surpasses its SQ.

Hamburg(20,54) (wine,wine) continent #21, iron working unknown

plains = 7
hills = 3
grass = 4
ocean = 7
rivers = 4

1650 hides,coal,wool dye,wine,beads size 3 techs:15
900 trade for Pottery
800 coal,wool,salt dye,copper,wine size 3 techs: 18

For both years I'm getting an SQ of 24 and a DQ of 26 for wool, putting it on the demand roster.

This may be due to the fact that I interpret temperate zone offsets to be distances, which are usually expressed as positive numbers. If negative offsets are possible, then wool will work correctly here.

In any event, I think this is an example of something that should be clarified in the geographical definitions.

[samson]

I count 5 grass and 6 plains at Hamburg which gives an SQ of 26 and a DQ of 24. I think that was the problem, a grass/plains crossover.

Temperate Zone Offsets are distances and should not be negative. You're interpretting the concept correctly.

[Elephant]

I come back from a week away and find you have solved it all. I'm so disappointed...

Now we need to "interpret" the results - where is a good place to plant an early city to get Dye or Hides, where is a good place to plant mid-game cities to get Oil, and later Uranium? Lets ponder some of these formulas and come up with some practical play suggestions. A few Excel spreadsheets might be helpful too...

[samson]

Hey, Elephant, nice to see you again. Well, there's still Dye and Copper demand, heh heh.

There's another thread already going (Strategic Implications of Understanding Supply and Demand) to address just the kinds of issues you raise. Feel free to contribute. I have some more ideas I'll be adding in a day or so.

[solo]

Samson,

One more thing we need more info on is about how spice demand works on continents other than the largest one.

Yes, I got those counts wrong for Hamburg, and I'm embarassed to admit that this still happened even after double-checking them! Maybe it's time give this a brief rest before resuming checks. I've been going at it pretty hard, but it's been a lot of fun.

Welcome back, Elephant!

[solo]

I've done a little more research on spice. After getting a spice demander from an EVEN city on my second largest continent, I decided to use settlers there to found cities to see if more spice demanders would appear on this continent. I was able to get another one fairly quickly with an American settler, but this time the city was ODD, giving an ODD and an EVEN spice demander on the same continent.

Attached is a zip file containing two hot saves, one illustrating spice demand by Philadelphia, an EVEN city and the second illustrating spice demand by an ODD city, Chicago. Both are on the second largest continent.

My conclusion from this is that spice demand is limited to ODD cities on the largest continent. On any other continent, any city may demand spice. This makes sense from a design viewpoint, since spice demand is determined by continent size. Spice demand would probably appear on most, if not all, demand lists early on for the largest continent, espcially in panagea map games, so the ODD rule was used to limit spice demand for the largest continent. On smaller continents, where spice DQ is less competitive, there was no need to limit its demand in this artificial way.

[samson]

Solo,

The "odd" spice rule could apply just to the largest continent, but I suspect that there's a size breakpoint at work here. By which I mean that if a continent's size is greater than a certain number, the odd-rule is invoked. For instance, what if there were two very large continents, like Eurasia and the Americas on your giga map; both would likely produce many spice-demanders. If the odd-rule only applied the largest, Eurasia, then the Americas would have many more spice-demanders.

On the "EVEN" hot save, Philadelphia seems to have been founded on this turn and immediately demands spice. However, when I run the numbers, it shouldn't be demanding spice. And if I deliver a caravan or use Reveal Map, the spice demand goes away and the "correct" commodities appear on the S/D lists.

This raises a question: is the founding of a city a "trigger event"? If so, then why is Philly demanding Spice?

[Elephant]

Originally posted by samson
Hey, Elephant, nice to see you again. Well, there's still Dye and Copper demand, heh heh.

There's another thread already going (Strategic Implications of Understanding Supply and Demand) to address just the kinds of issues you raise. Feel free to contribute. I have some more ideas I'll be adding in a day or so.

Leaving the toughest for last, huh?

My apologies for missing the "Strategic Implications" thread. I had just read through the week I missed (as well as 350 "business" emails...) and popped a comment in at the end. Then I started looking at your formulas. I hit your Implications thread around 12:30 last night...

I'll post some thoughts on Implications over there after I finish digesting the formulas (and maybe a bit of turkey? ). Just wanted to post a quick but heart-felt THANKS for all your hard work on this issue. Between the Solo Cycle and the Samson S/D Formulas I hope we can reduce the frustration of bringing that Gold caravan up to Babylon's gates only to have the demand disappear at the last minute. There ought to be an award for this kind of achievement...

[solo]

Samson,

When I run the numbers on Philly, I'm getting spice = 15, putting in the third slot, after hides and wine. The closest competitor I see is cloth, which I compute as 11. Silver and gems come in at 8 each, even lower. Silk, dye, wool and salt are all on the supply roster.

Philly(65,23) (gems,beads), continent #1

my terrain counts (known to be in error in the past!)

grass = 7
mountains = 2
forest = 2
plains = 1
ocean = 9
rivers = 2

dye,gems,salt hides,wine,spice size 1 techs: 14

looks ok to me for 1550. (beads is under gems)

In 1050, Philly's cycle turn, the lists were:

beads,gems,silk dye,hides,wine size 2 techs: 14

with dye pushing spice off the demand list. (salt under gems)

It looks to me like formulas are being obeyed when cities are founded. I had the same thing happen to two cities on the largest continent. When founded, they showed dye in slot #3, but on their first cycle turn, dye displaced spice from their demand lists. Original numbers were wanting spice on the foundation date demand lists.

If your numbers prove to be correct, then I agree that something weird may be going on with spice, or that there was a glitch to the list when Philly was founded. We have seen evidence of glitches in lists, such as when Washington was allowed to build a dye caravan, when dye was not in supply. Elephant, here is your golden opportunity! Please figure out what's going on.

Your other point about North America on the giga map is well taken. Although there were not many cities on that continent, I would expect at least 1 or 2 spice demanders because of its size. As usual, the plot thickens, and there may be more to spice demand than seems apparent now.

[samson]

You're right. Philly's spice demand is legit.
And city-founding is a trigger, so the initial S/D lists should be correct.

Re: Triggers.

As you know, on a solo-year every city whose city number plus the turn number is Mod-16 will have its S/D list updated automatically at the beginning of the turn. But every viewing of the City Display screen on a city's solo-year is also a trigger that updates the S/D lists.

For example, if you trade for Nuclear Fission, this doesn't automatically change any of your cities' S/D lists. But if you then view the City Display of a solo-year city, this act will update the demand list with Uranium.

The solo-year automatic update appears to occur before other updates to a city on the pre-turn cycle. For example, if a city's size increases during its solo-year any changes this might have on the S/D lists are not automatically updated. But if you view the City Display, then the size-related changes are triggered and are applied. However, if you don't view the City Display that year but wait until the next turn (when City Diplay viewing is not a trigger) then you'll see the S/D list status pre-size change. Tricky isn't it?

[solo]

Wow! I did a few tests on this with a few cities going through size changes, and it's even trickier than what you describe. For example, Hamburg turned size 3 on its cycle turn, and built a temple on that turn, too. Here are the various lists:

before 1650 hides,coal,wool dye,beads,wine
1650 zoom for temple hides,dye,coal beads,wine,silk
1650 after zoom hides,coal,wool dye,wine,beads

Now if you don't zoom in 1650 and just look later, you get 1650 after zoom, but if you do not zoom and also do not look, the following turn you get what you saw for the 1650 zoom!

Another city I looked at was Veii, that turned size 4 on its cycle turn of 800 without building anything. If you look at Veii during that turn, nothing has changed, but if you do not look at Veii and wait until the turn after its cycle turn, the lists change in a radical way:

before 800 silk,salt,silver dye,copper,spice
look during 800 same as above
wait and look on next turn silk,salt,dye spice,copper,beads

This is really weird, because dye, usually solidly entrenched as the #1 demand, has moved onto the supply lists for both Veii and Hamburg! This may explain how Washington was able to build dye with a caravan completed on a cycle turn, when I never saw dye supplied. If zooms were built into caravan builds, I bet I would have seen dye on Washington's supply list during the zoom.

During previous tests, I have been looking on every zoom and also looking at every city on every turn, but now it seems that not looking postpones the cycle trigger! I wonder how long? I'll have to do some more checking into what not looking can do!

The implications here are a bit mind boggling. I see the possibility of timing your trigger to when you want to have it occur by not looking, and another possibility of manipulating lists by postponing looks. There seems to be a definite glitch at work here, and the fact that I was able to move dye out of demand with a postponed look may suggest that dye is not stuck on the demand list by purpose, but instead, accidently with cycle turn looks.

Maybe the lists only work correctly if cycle turn looks are omitted. I remember you saying that dye did not behave "correctly" during games, according to observations made in your tests.

[samson]

Solo,

Both the cases you describe are following the solo-year trigger-law exactly as I stated it. It's just that when using MGE you have to contend with the Dye/Copper bug as well.

What you see in Hamburg when Zooming after the temple build is the result of the automatic solo-year update. This actually corrects the Dye/Copper problem and Dye shows up on the Supply list where it belongs. However, using Display City during a solo-year causes another update and, unfortunately, on MGE this re-instates the Dye/Copper demand distortion. If you don't use Display City in a solo-year, then the "correct" values will fix for the next 15 turns. Unless, of course, the city is involved in a caravan delivery which re-invokes the Dye/Copper bug.

but now it seems that not looking postpones the cycle trigger!

No. A city's lists are updated automatically only during its cycle-year. The trigger isn't postponed. When you look at a city in a non-cycle year it has no effect, you are merely seeing the cycle-year updates for the first time. Try using Trade Advisor during a cycle year instead of Display City, it will show the automatic updates without triggering the Dye/Copper bug.

[solo]

A brief update on this. For cities that have list changes on cycle turns, but do not have size changes or tech changes on these turns, delaying a look until after the cycle turn produces different lists, again with dye moving from demand to supply. Ditto for a delay of another turn. Looking on cycle turns makes something different happen. My observations are from a hot seat MP game. Things may work differently in SP, and even in 2.42 games.

[samson]

A brief update on this. For cities that have list changes on cycle turns, but do not have size changes or tech changes on these turns, delaying a look until after the cycle turn produces different lists, again with dye moving from demand to supply. Ditto for a delay of another turn. Looking on cycle turns makes something different happen.

Solo, you are observing the same phenomenon I described but attributing a different cause to it. What's happening is just what I said: Viewing the City Display on a cycle-year is a trigger-event. So is the automatic update at the beginning of a cycle-year turn. The automatic update corrects the Dye/Copper distortion, but Viewing the City Display in that year reinstates it. It works the same way on 2.4.2 except without the Dye/Copper bug. [Actually 2.4.2 has its own Dye/Copper problem but it manifests differently.]

There's a bit of Heisenberg at work here, but it's not entirely unpredictable.

[solo]

Okay, I did not see your reply to my first post on this. What you say makes sense to me, but if dye-copper bug is not implemented by cycle turn looks, then their "correct" demand values should be lower, right?

In any event, I can alter or "correct" lists by choosing to delay looks until after cycle turns in MGE games, or use cycle turn looks if I want "bugged" lists.

From what you say, in 2.42, a cycle turn look always gives a "correct" and updated list. If so, this is a radical difference between game versions.