Granary is OP for computer on Emperor.

[tupi]

Every next difficulty transition is more steeper than the previous, this is just how this number progression works:

warlord 14
prince 12 (-15%)
prince (player dominance)/king 10 (-16%)
king (player dominance)/emperor 8 (-20%)
emp.(pl.dominance)/emperor+1 6 (-25%)
emp+1(pl.dominance)/emperor+2 4 (-33%)

So it is ok that Emperor feels so much harder than King, right? And Emperor+1 is much harder than Emperor, even if AI is sometimes is more strange and glitchy, so it can be handy.

But any player, on any difficulty, gets the same food bonus from a granary in their city: 5*city_size+5. This is half of needed food to grow to a next level for human player or for AI player on King difficulty:

granary on king (from size 1 to size 2):
computer: needs 15 food units for next growth
player: needs 15 food units for next growth

But on emperor, the effect of this is pretty big:

granary on emperor (from size 1 to size 2):
computer: it needs 24-15=9 food units for next growth. (-40% compared to the human player! even though its "normal" bonus is only -20%!)

granary on emperor (player dominance)/emperor+1 (from size 1 to size 2):
computer: it needs 18-15=3 (!) food units for next growth (-80% compared to the human player!)

So probably THIS is why emperor is so much harder than king difficulty! When you dominate the game after 1 A.D., AI cities with granaries grow five times as fast as your cities with granaries, or tenfold compared to your cities without granaries. These We Love the President Days is your only hope.

With this arithmetic, we can also understand these glitchy overpopulated cities on non-standard difficulties:

granary on emperor+2 is becoming strange:
computer: granary granted 15 food units, but for growth only 12 food units are needed. So next level is granted next turn, if we still have enough food surplus. It will continue, this way you have these glitchy overpopulated AI cities on "extra" difficulties. Eventually, there will be more consumed food every turn than is needed for a city to grow every turn, and this city will start to shrink. If eventually, in the result of shrinking, there will be any surplus of food, sooner or later it will trigger a new wave of growth, and so on.

Example:
with basic multiplier 4 (emperor+2/emperor+1 player dominance):
size: 20=>21 surplus (for example): 1=>-1 food created by granary: 110 result: 109. Food needed for next growth: 88 => growth
size: 21=>22 surplus: -1=>-3 food created by granary: 115 result: 112. Food needed for next growth: 92 => growth
+1 -2 +5 +3 +4
size: 40=>41 surplus:-39=>-41 food created by granary:210 result:169. Food needed for next growth:168 => growth
size: 41=>42 surplus:-41=>-43 food created by granary:215 result:172. Food needed for next growth:172 => growth
size: 42=>43 surplus:-43=>-45 food created by granary:220 result:175. Food needed for next growth:176 => famine after a few turns (-45 food each turn, then city will shrink by 1 each turn until size 20)

 

[pureciv]

The computer needs the 5-1 advantage because the AI is severly lacking in many places.
"Friendly" civs are oblivious to threats and hardly defend their massive cities with one or two units, while poor Genghis and Alexander have 3units per point of population.
After taking a break from the game, the primary sore point of Civ is over-aggressiveness of the aggressive setting (or even non-aggressive ones?) which means sharing a land mass with them or not is the primary determinant of your gameplay experience.
And also the mechanism of resource support for units, which means you're either on high alert with neighbours, or you can have no military with reckless abandon and develop society at many times the speed of others, where the 'benefits' of neighbours is minimal in comparison to being alone.
Surely there is some way to make 'middle ground' better with neighbours.. trade does not rely on friendly relations and only on distance.. there is no incentive to co-exist.

 

[Mize]

Surely there is some way to make 'middle ground' better with neighbours.. trade does not rely on friendly relations and only on distance.. there is no incentive to co-exist.

I'd argue about that. Distance is only a factor in trade if you need the big one-time bonuses (or if the only good trade cities are far away). But if you want easy to get high-yield trade routes, keeping a small civilized neighbour around can be very profitable. You get all your trade routes up quicker with no risky overseas voyages and you can shake them down for some serious cash, before you go for republic/democracy. There is a high probability they will lash out at you later on, but I've also had quite a few games in which peace was never--or very rarely--broken. Obviously, this is almost impossible and completely pointless with the more militaristic civs like the Russians and the Mongols. Weirdly, I've had the most success with keeping Napoleon as a pet.

granary on emperor (player dominance)/emperor+1 (from size 1 to size 2):
computer: it needs 18-15=3 (!) food units for next growth (-80% compared to the human player!)

I'm pretty sure this is not correct. Dominated emperor AI after 1AD needs 12 food to grow from size 1 to size 2 and the granary doesn't really count here, the city still has to generate food to fill the first half of the box. The bonus should still be -40%, unless I'm missing something.