[freeciv-ai] More on AI Diplomacy v8 (PR#2413)

["Per I. Mathisen" <per@xxxxxxxxxxx>]

Here are a few problem areas that maybe someone would like to comment on
separately:

1. The dist_to_empire() function is very crude. A better algorithm here
would be much appreciated. In short, it calculates the average distance
from your capital to all the other player's cities.

2. Maybe pplayer_allied_with_enemy() and pplayer_war_with_ally() and
pplayer_is_allied_with_ally should be calculated in aidata.c, then read
from an aidata variable, to avoid too many calls to these functions.

3. mistrust_to_gold() is awful. A better algorithm is much desired.

4. ai_goldequiv_city() may not be good enough. At least it should do more
checks, like ensuring that we get enough defensive troops in the city to
defend it for one turn. On the other hand, we only accept cities from
players we are in peace with.

5. We don't suggest trading techs with players we are not allied with.
This should be implement at some point, but not necessarily before cvs
inclusion.

6. Should AIs that are almost completely destroyed surrender? That would
save players some unnecessary time wiping up the last remnants of an AI
enemy that has no chance in hell of putting up some amusing resistance.
Human players usually quit when they know they have lost, I think.

7. A target_players_iterate(pplayer, aplayer) iterator which skips dead
players and also pplayer would be very useful in simplifying code. Should
beparate patch, though.

8. Someone should playtest the spacerace part of the code. It has received
very little playtesting by me.

9. We don't consider going to war against NO_CONTACT players. This may be
a very bad idea, I am not sure. The reason is that I suppose that
NO_CONTACT players are further away and we won't be able to reach them. On
the other hand, they might be the ultimate enemy that we want to gang up
on.

10. We do not check if peaceful expansion is superior to war. We should,
ideally, check if our rate of growth is faster than that of our chosen
target. However, this is in practice rather hard to do, especially since
our allies may be opting for war (where's the Security Council when you
need it?).

  - Per