I think AI cheats!

[SirSebastian]

Notice that pyrhic said, "...and the ai doesn't usually stockpile gold."

My guess would be that the AI was having a bit of trouble with ancient units staying around for too long. Since the AI doesn't generally have tons of gold laying around, a quick solution is to give the AI a break on upgrading units so that it will "see" that as a good use of its current gold. It would certainly be preferable if the AI could say, "Oh! I want to lower my science rate because I expect to be needing expensive upgrades in the near future!" My guess would be that someone got fed up with that and just gave them a discount.

After all, that's probably the kind of check that would be every turn by each AI civ, and it may have been very difficult to have it work intelligently (checking each unit to see how important it is? check the tech tree for upgraded units possibly available soon? Adjusting the science rate - when and by how much?) Not to mention that the AI probably has a very poor idea of which units to upgrade and when to upgrade them. It's probably done in a very simplistic cpu-friendly way. While I don't like it, it's certainly something that I can live with and is understandable.

[linkhan]

So we both agree that we don't like it.
You can live with it, but I... I don't know yet. :P
I guess it really isn't that big of a deal, but it does curb my expectations (downwards).

And yes, I did notice pyric's note on no stockpiling. So the feature is more of a workaround to a
coding limitation, at least according to you.

From an implementation point of view, I think the AI can be tweaked so that it's accumulating *some* gold for unforeseen circumstances (e.g. human player has an armada off the coast). I can see how it could be involved if we take all the facets you listed into consideration, but a simple "Savings account" formula would be preferrable to me giving it a break in terms of a steep upgrade discount. Yes, that'd probably cut into the science, (but hey, they have production bonuses already!)

I haven't confirmed this in the game yet, but from the info I've gathered, we could be seeing this with "upgrade bonuses":

Potentially, it's like playing against X number of Civs and all of them having the Leonardo's Workshop a la Civ2 style. Back in Civ2, you clearly saw the power of that wonder for ANY civilization that had it, including yourself. Sure, you don't see instant upgrades across their continent, but instead it's triggered by you being close to the gates. As far as you're concerned, YES, you will be fighting their most upgraded units everytime you come close to their next city. So, unless AI can run out of gold upgrading units, in effect you're fighting all AI Civs with Civ2-style Leonardo's Workshop.

It affects the strategy of the game now, since it curbs the element of surprise you can have when you attack a city. We pay for it when we're caught with our pants down. It's only fair that we can do the same, at least in Noble difficulty.

I don't remember seeing these instant panic-style upgrades in Civ2.
Civ1 had no concept of unit upgrades, save building newer units.
Didn't play Civ3 cause rampant AI cheating was a total turnoff.
I'm finding this "upgrade bonus" a turnoff in Civ4.

[Handel]

No matter how the devs try, they cannot make a real "human" AI, so they will always, or at least in the near future, give to the AI all kind of bonuses. I send a lot of missionaries to convert in my religion (I hold the Holy City) and they act as spies too - so usually the big AI cities have more then 15 units each. This is on the prince level and it is absolutely sure the AI get most, if not all, of his units w/o any upkeep. Not to mention the research. Right now Egypt has only 2 cities left and nevertheless they had techs which I didn't research. And this is on prince level.

[linkhan]

I rest my case