AI psychology: a thread attempting to analyze it´s behavior (contribs. welcome)

[The Unknown Guy]

To start it: some things I´ve noticed

- When a faction starts to get pushed in one front but is still strong in the other, they´ll make an attempt at hacking at their other neighbour´s borders, if they think they´re weak, to get adittional breathing space. If you´re strong and already at war, and they are getting pummeled, they´ll immediatedly sue for peace

- Low influence and risks of civil war induce warlords to sue for peace.

- Bankrupcy and large armies induce warlords to hack at neighbours' provinces (tested by seeing how the computer attacked and then refused to ransom a crown prince and other 200 high rate units)

- Royal marriages are easier to get if the target princess is getting moldy.
Likewise, wars handicap your diplomatic attempts at RMs and alliances.

- As always, an undefended province is always a tempting target for enemies. Don´t forget to protect your soft underbelly and cover coasts with fleets.

- The enemy seldom uses spies, but it will often use assasins.

- Low loyalty means cheap bribe prices. The computer does not bribe too often, not enemies, at least, but it does hit on cheap unit stacks from time to time. Specially rebels (as everyone does).

- Peculiar Egyptian-Turkish-Byzantine relations:
-Turkey and Byzantium will almost always get to war. Particular detonating points are bankrupcy(as stated above) and apparently getting close to GH emergence. This war can be prevented if you marry off a Byz princess to a turkish prince
- Egypt is Byzantium´s staunch ally. Unless you hold lesser armenia or other common frontier, in which case it will strike again and again, even if they´re the losers for influence loss. So, if you want to trade, it´s a good idea to keep the turks alive, even if you kick them out of Anatolia and Rumelia.

-Peculiar Golden Horde behavior:
They always let crusades through

- My theory on the "War Pope": it is triggered by papal bankrupcy and/or utter vulnerability of lands. Once playing Byz the pope attacked and suffered a horrible defeat in my newly conçuered Naples. They sued for peace the following year

[guelphling]

In my Turk campaigns I always ally with the Egyptians straight away. I go to war with Byzantium and before to long the yellow peasant brigades invading Syria. I will never understand why they don't attempt to go after the Almos?

I'm going to try to concede Syria via tax induced rebellion maybe that might promote a few more years of peace.

[General Dazza]

In my Turk campaigns I always ally with the Egyptians straight away. I go to war with Byzantium and before to long the yellow peasant brigades invading Syria. I will never understand why they don't attempt to go after the Almos?

I'm going to try to concede Syria via tax induced rebellion maybe that might promote a few more years of peace.

Welcome to the Org guelphling

If you pull all your troops out and raise taxes you should manage to create rebellion.

- Low influence and risks of civil war induce warlords to sue for peace.

I don't think I've had a country sue for peace with me while I'm pushing them to civil war Unkown.

- My theory on the "War Pope": it is triggered by papal bankrupcy and/or utter vulnerability of lands. Once playing Byz the pope attacked and suffered a horrible defeat in my newly conçuered Naples. They sued for peace the following year.

This is true. I think if the Pope has strength he'll attack where an opportunity/need arises, but if he suffers a significant defeat he'll quickly sue for peace (and even form an alliance from what I've seen).

[caravel]

To start it: some things I´ve noticed

- When a faction starts to get pushed in one front but is still strong in the other, they´ll make an attempt at hacking at their other neighbour´s borders, if they think they´re weak, to get adittional breathing space. If you´re strong and already at war, and they are getting pummeled, they´ll immediatedly sue for peace

The AI is a simple beast but it appears to work like you say which is good enough and adds to the immersion factor. What usually occurs is, that the AI get's beaten and loses provinces, this produces larger stacks coming together in the backwater provinces. The AI then simply checks it's neighbours forces against it's own bloated stacks and invades them. This is why a reappearing faction has a tendency to spread out quickly. Large stacks mean that it can divide them up and use them for multiple invasions. I have often turned my faction over to AI control to see what it does with my forces. In most cases it will quickly spread out and conquer half of the map, then due to being spread to thinly it's empire will fall apart and be absorbed by a reappearing faction, and so the cycle begins anew.

- Low influence and risks of civil war induce warlords to sue for peace.

I've never noticed this in MTW much, in STW yes, but you could very well be right, possibly it occurs though to a lesser degree.

- Bankrupcy and large armies induce warlords to hack at neighbours' provinces (tested by seeing how the computer attacked and then refused to ransom a crown prince and other 200 high rate units)

I think this applies to your first point. Bankruptcy is just a result of high support costs in provinces incapable of supporting those units. The AI will eventually break out and attempt an invasion if it perceives it's neighbour to be weaker. The Aragonese will pretty much always try on an invasion of Tolouse eventually, if the garrison there is too weak. The same goes for the Danes with regard to Saxony. This is because they will eventually stock up with a lot of Royal Knights (causing bankruptcy) and when checking the overall power of their army and their neighbours they will find theirs to be superior. The AI doesn't go on numbers alone, but on the general and class and valour of the units defending the province. The AI must work out it's invasion probability from these factors. I have often found that the AI attacks my provinces the following year that I've moved a high command general or an elite unit out.

- Royal marriages are easier to get if the target princess is getting moldy.
Likewise, wars handicap your diplomatic attempts at RMs and alliances.

Another one I've never noticed, though I don't see why it couldn't work like that.

- As always, an undefended province is always a tempting target for enemies. Don´t forget to protect your soft underbelly and cover coasts with fleets.

An undefended province is always a target but there is an overriding factor and that is whether the AI wants the province or not. I have tested abandoning provinces to my enemies and allies alike, and and found that the AI often ignores them for years. In fact on many occasions they only attacked after the province had rebelled. I have yet to understand why this occurs, but it appears that the A goes for certain provinces and ignores others, it doesn't simply try to take everything indiscriminately.

- The enemy seldom uses spies, but it will often use assasins.

True, though this is mainly due to the higher building requirements for spies. Also, the AI is not effective in their use in that it cannot carry out any of the subterfuge missions. The AI can only move spies around and leave them in provinces. I have often seen the AI train about 5 spies and then simply leave them in that province for the duration of the campaign. In another case the AI trained the spies in Greece and then moved them to Serbia, and no further. They remained there for the duration.

- Low loyalty means cheap bribe prices. The computer does not bribe too often, not enemies, at least, but it does hit on cheap unit stacks from time to time. Specially rebels (as everyone does).

It seems to be the case. The lower the loyalty the cheaper the bribe. Rebel stacks appear to be cheap simply because most rebel generals have 0 loyalty.

- Peculiar Egyptian-Turkish-Byzantine relations:
-Turkey and Byzantium will almost always get to war. Particular detonating points are bankrupcy(as stated above) and apparently getting close to GH emergence. This war can be prevented if you marry off a Byz princess to a turkish prince

- Egypt is Byzantium´s staunch ally. Unless you hold lesser armenia or other common frontier, in which case it will strike again and again, even if they´re the losers for influence loss. So, if you want to trade, it´s a good idea to keep the turks alive, even if you kick them out of Anatolia and Rumelia.

AI Turks and Byzantines will almost always go to war yes. Again bankruptcy is a symptom of the AI having used all of it's resources to spam large stacks. It will then "vent" those stacks into surrounding provinces. As the player playing as the Turkish/early you can avert War with the Byzantine fairly easily, by simply not attacking them. They will usualy not ally with you however. The Egyptians on the other hand will ally with you, but will always invade Syria at some point early on. It is only when the Turks are out of the picture that the Byzantine and Egyptians will start on each other. I believe this occurs due to the AI "choosing" it's allies and enemies from among it's neighbours. It would be interesting to edit the startpos file and switch the Egyptians and Turks to each other's provinces and see if that changes the Byzantine attitude to them, I feel it would and that the Byzabntine and Turks are hostile simply due of the number of shared borders (Lesser Armenia/Rum, Anatolia/Rum, Trebizond/Rum, Georgia/Armenia, Trebizond/Armenia), many more than the Egyptians share with the Byzantine (Lesser Armenia/Antioch) and more than the Egyptians share with the Turks (Syria/Arabia, Syria/Antioch, Syria/Tripoli, Syria/Palestine). So (IIRC) the Egyptians share 4 borders with the Turks, the Turks share 5 borders with the Byzantines whom only share 1 border with the Egyptians.

We can apply this to other factions that share many borders such as the English and French, the French and HRE and the HRE and Hungarians. All of these factions seem to end up at war with each other.

-Peculiar Golden Horde behavior:
They always let crusades through

Not always, it depends on allied/neutral/war status. The AI will check the crusade against it's army stack in the province to see if it can win. I've ha similar problems with the Byzantine blocking my crusades for no apparent reason. It seems that if your crusade is perceived to be weak and your faction is not allied then it increases the chances of this occurring, when passing through pagan or orthodox lands.

- My theory on the "War Pope": it is triggered by papal bankrupcy and/or utter vulnerability of lands. Once playing Byz the pope attacked and suffered a horrible defeat in my newly conçuered Naples. They sued for peace the following year

I've never understood the papacy, but they do use use a different AI script I believe so it may be that they're programmed to try and provoke the player into wiping them out. It seems that way sometimes.

[Noir]

Interesting topic - just to post my comments on certain factors affecting AI behaviour.

It should be mentioned that the starting Ai "personality" also influences choices and strategies for a faction up to a point (that point usually is when they are too powerful to stop). A catholic-defensive-crusader will develop/respond different than the catholic-expansonist-crusader.

Also, the building flow/construction requirements are crippling the AI in the vanilla game as he will go on to complete castles and military buildings before even considering making financial buildings. Valor bonus provinces are further crippling, as Cambyses II has pointed out in an older thread (and as i and prolly others have found independently or not) the AI will stop developing the province once he reaches the buildings required for the unit that gets the bonus.

Since he cannot disband armies/fleets, he can only get rid of armies through war attrition, and this is why there has to be a constant level of warmaking throughout a campaign but with slow conquering advances, to keep the AI economy constantly healthy and the game interesting.

In my home mod of Medmod IV, i have allowed all military buildings of all levels to be built at the third level castle, have standardised their cost to 400 and their building times at 4 turns - and it works wonders as the AI gets through with building them in the first 25 turns or so... It wont make him any better militarily wise as the new units won't come in until the next era and when it comes everyone has access to them immediately. Also the logistical strength of each faction in numbers is regulated by home provinces: for example the Italian factions (Venice-Genoa) have 4, that's two each - while the HRE, France and the Byzantines have about a dozen each. So, it doesn't matter how many provinces the AI develops militarily but how many of his homelands he has bdeveloped and has available.

The two larger fort levels have only cultural/advanced tech buildings associated with them that in the MedMod IV are unique; this makes for less Citadels and fortresses that in most cases in the vanilla game are a huge waste of funds and most importantly time for the AI factions (since they build 3 to 5 of them whithin 100 to 130 turns).

With all valour provinces removed (that's actually with the removal of the upgrades and the nerfing of command stars a plus/plus for tactical battles) and without taking ages and millions to develop military infrastructure, the AI is actually a decent strategic player, developing the economy with a lag of about 5 to 12 turns slower than the human player, i found out.

The true problem is what happens once the AI gets good money; he usually spams troops/fleets/agents until with the first stumble he is in the red by a lot. This is why the emphasis in agricultural income in XL works so well - these stumbles (read loss of trade routes) are less frequent.

Once the AI gets really rich, no matter what his personality background he goes megalomaniac and spreads in the way Cambyses II described till he gets fragmeneted and devoured by others and so on.

The two best ways to make sure this is happening at a reasonable pace/quantity are strict homelands and high rebellion (about 2 in the startpos file) provinces.

The first, ensures that the AI faction that largely deviates from its homelands is doomed, sooner or later (as they cannot replenish their armies fast enough) and the second that the advancing rate of a conqueror is about 1/8 of that in the vanilla game. Both these are good as the game is not "over" in 45 turns or so, neither do you see the all familiar territory exchange of vanilla (Egyptians in place of Turks - English in place of Turks and vice versa after a war between them).

Overall, the AI can do well, and could do really well if there was a disband fleets/units script built into it and a function of selectivity for building choices once he has a lot of cash.

[caravel]

Also, the building flow/construction requirements are crippling the AI in the vanilla game as he will go on to complete castles and military buildings before even considering making financial buildings. Valor bonus provinces are further crippling, as Cambyses II has pointed out in an older thread (and as i and prolly others have found independently or not) the AI will stop developing the province once he reaches the buildings required for the unit that gets the bonus.

The AI definitely develops a province in order to train the valour bonus unit before it does anything else. I have not seen much evidence of the AI continuing to develop the province after it has teched up to the valour bonus unit either. This is really a grey area that needs considerably more testing. I have seriously considered removing all valour bonus regions from the mod, but that would be very unpopular with many players, and understandably so.

Since he cannot disband armies/fleets, he can only get rid of armies through war attrition, and this is why there has to be a constant level of warmaking throughout a campaign but with slow conquering advances, to keep the AI economy constantly healthy and the game interesting.

This is the big problem. The AI cannot disband any units, so the more money you give it the more it spams, and the worse it gets. So throwing money at the problem is never a solution. Controlling and regulating it is the key.

In my home mod of Medmod IV, i have allowed all military buildings of all levels to be built at the third level castle, have standardised their cost to 400 and their building times at 4 turns - and it works wonders as the AI gets through with building them in the first 25 turns or so... It wont make him any better militarily wise as the new units won't come in until the next era and when it comes everyone has access to them immediately. Also the logistical strength of each faction in numbers is regulated by home provinces: for example the Italian factions (Venice-Genoa) have 4, that's two each - while the HRE, France and the Byzantines have about a dozen each. So, it doesn't matter how many provinces the AI develops militarily but how many of his homelands he has bdeveloped and has available.

That is a good approach, I have been working on something similar for quite some time. I have looked into removing the fort level altogether and reducing the build time and cost of the upper castle levels. The fort I would have as a simple garrison building, costing 100 and taking 1 year to build, as a temporary outpost to hold down a province - not a town/settlement. The only buildings that could be constructed at fort level would be the farmland, port and mines. The horse breeders I would change to depend on the later castle levels instead of being fully upgradeable, and the swordsmith and armourer would be levelled off to correspond with the spearmaker and bowyer, none of these would depend on each other, but would be individuals. The startpos would be edited so that every province starts with a fort.

[macsen rufus]

As always, an undefended province is always a tempting target for enemies

I have on occasion had the exact opposite experience. Can't recall the factions/provinces involved but I got to a point in one game where an overwhelming invasion occured. I reloaded, increased my garrison, and the AI invasion was larger. Same again, even bigger. In the end I decided the province was undefendable, so reduced the garrison to just enough to maintain loyalty. Guess what? The AI didn't invade, and indeed that entire war never happened! So in some circumstances it seems that a more heavily defended province can be MORE of a temptation to the AI that an effectively undefended one. It might be down to the fact that the AI couldn't "see" what armies I might have had in a potential "counterattack province", or maybe my border garrison was a "provocation" to it.

[Noir]

Originally posted by Cambyses II
I have seriously considered removing all valour bonus regions from the mod, but that would be very unpopular with many players, and understandably so.

Well, perhaps, however i have kept at a minimum campaign related factors that can influence the stats of units. I removed the armour and weapon upgrades, valour bonuses, morale uprades and nerfed significantly the default command stars (ranging from 0 to 4 now as a start) as mentioned earlier. These in my opinion only provide a distortion of the battles as rich factions can afford to make their units better, something which i dislike. Upgrades and jedai units being campaign winners are a huge spoiler for me. There's nothing worse than winning battles simply because your swords will beat the enemy swords and your spears will beat the enemy spears and so on. Tactics are not needed anymore passed that point.

In addition, i have regulated the maintencance costs/rebbeliousness of provinces in order to give no more than a stack+ a couple of units max per province for the AI factions and make it popssible to invade a neighbouring province at the cost though of having the newly conquered and the owned province rebelled if not careful/not having happy buildings etc etc.

This implies that apart from the horde and crusades/jihads, there are few battles to be fought with more than a full stack vs a full stack, which i find is perfect - more than that and battles become multihour chores that you know you'll win versus usually a fragmented and leaderless (after the initial melee) mob, but still you have to sit out in the pc.

As for the popularity of all this, well, i personally enjoy the game in this way. I understand very well that the rules change if you are making a released mod though.

Relative to the AI developing provinces until he reaches the requirements for the valor bonus, there is no doubt about it. I have played several Byzzantine campaigns in the MedoMod IV with the AI controlling building/training. He never did once built anything in Constantinople (Tharce in the mod) despite the fact that its the most ludicrous province commercially (together with Egypt, Sicily, Algeria, Provence, Venice, Aragon, and Khazar). That's because the katafracts that were getting the bonus there were already available. Once i've removed the bonus... surprise, surprise: the AI was making 1600 to 2300 in Constantinople in 20 turns in the majority of the cases, not so much different than what i was able to achieve.

[caravel]

I removed the armour and weapon upgrades, valour bonuses, morale uprades and nerfed significantly the default command stars (ranging from 0 to 4 now as a start) as mentioned earlier. These in my opinion only provide a distortion of the battles as rich factions can afford to make their units better, something which i dislike. Upgrades and jedai units being campaign winners are a huge spoiler for me. There's nothing worse than winning battles simply because your swords will beat the enemy swords and your spears will beat the enemy spears and so on. Tactics are not needed anymore passed that point.

I also plan to reduce the starting command stars of all generals/faction leaders. Especially with regard to the Byzantine that are just ridiculous. Weapon and valour upgrades are a factor I prefer to retain. I have instead improved the availability of Iron, giving Iron to most factions. It also seems historical that those richer factions should end up with better weapons and armour over time. I find uber units to be a bigger problem and have taken steps to tone down many of these and 'soup up' a lot of the underperforming and redundant units to give better balance.

Relative to the AI developing provinces until he reaches the requirements for the valor bonus, there is no doubt about it. I have played several Byzzantine campaigns in the MedoMod IV with the AI controlling building/training. He never did once built anything in Constantinople (Tharce in the mod) despite the fact that its the most ludicrous province commercially (together with Egypt, Sicily, Algeria, Provence, Venice, Aragon, and Khazar). That's because the katafracts that were getting the bonus there were already available. Once i've removed the bonus... surprise, surprise: the AI was making 1600 to 2300 in Constantinople in 20 turns in the majority of the cases, not so much different than what i was able to achieve.

I've removed the Chivalric Foot Knights Bonus from Ile de France and replaced it with the Chivalric Knights Bonus from Toulouse. As a result I now have a Toulouse that gets well developed for trade, and an Ile de France that is built up to produce Feudal Knights and Chivalric Knights. Not a bad trade off but still far from ideal. There is also a valour bonus in Flanders for Pikemen. The AI techs straight up to Citadel level and upgrades the Town watch and Spearmaker to the same level while doing... nothing else.

The valour bonus is like saying to the AI "if you build it they will come". The AI then proceeds to invest all of it's florins and efforts into teching up to train the valour bonus unit, even if it can't actually build that unit until the high/late era.

[Noir]

Originally posted by Cambyses II
Weapon and valour upgrades are a factor I prefer to retain. I have instead improved the availability of Iron, giving Iron to most factions. It also seems historical that those richer factions should end up with better weapons and armour over time.

Historical as it may be, the armour/weapon tradition of a unit is also reflected in its stats, for example knights have a lot of armour, while say desert archers dont. Also the "professionality" of some units is reflected in their default stats. The Eras (the different rosters that they provide) may and do account for this pretty accurately i find (as you can build a trend/development into them for every faction/factions).

The upgrdades distort the default stats adding a superiority over units of the same use/caliber in the battlefield that i find disturbing as it makes enemy battle lines route with equal match-ups without the need to do anything further. Morale upgrades (and armour/valour upgrdaes) shift the focus of battle gameplay from balance between match ups (that the AI is good at) and flank attacks (that the AI is decent at) towards the latter. This is also disturbing, bad match ups should be punished - they should not provide the player with very much time to sort them out by virtue of a unit getting beaten fighting to the last man... Morale becomes a no factor then. When morale is just about, there is a fine balance that needs to be kept in order so that units don't route - keeping this balance is part of the genious of the TW games and it's what triggers the combined arms approach. Morale injections from high command and religious buildings/military buildings and defensive upgrades/stats injections make this factor of lower importance and quite often non-existing - its like playing with AoE units.

The worse however is that upgrades often benefit the player - the AI has a chance to use them only when it becomes very fat ie have swallowed a couple of other factions and now he's betting for taking over entirely. A propos, the AI prioritises the upgrades, which is his downfall financially as they take ages to complete and he goes on to complete them all from the early era (doesn't build gradually). This means that the longer you play a campaign the larger the distortion gets as some factions (few) have all the upgrdades and some others (many) don't even have that era's units.

This is the sort of challenge CA (and some mods - not referring to the pocket mod) promote/choose: bigger, bigger, bigger so the player has to be bigger, bigger, bigger as well. IMO challenge is based on keeping things on the line and for doing this, mechanisms of preventing gigantism need to be pronounced/introduced. Some of these mechanisms are already in the game but are nerfed considerably to allow grand scale conquest in 65 turns, which frankly i detest.

Of course, redundant/overpowered units are a major issue.

All in all i am happy if i play say 20 to 30 balanced single vs balanced single stack battles in 200 turns that i have a more or less 50-50 chance win/lose than playing 50-60, 4 vs 4 stacks battles -the former are real fun while the later are most of the time chores, as far as i am concerned.

Apologies to the OP, as this is off topic.

[The Unknown Guy]

On naval invasions: is it just me, or the AI tends NOT to perform them? I´ve only seen a proper attempt at a naval invasion, (AKA: moving a decent fleet to protect the invasion route, beating off enemy attacks) at Egyptian hands, to take French or Rebel Cyprus.

[Noir]

The way Ai does naval invasions is to decrease the support costs of his fleets. Say you are trading from Venice to Khazar. For every sea reagion that you occupy from your home port the meintenacnce cost is +the base maint. amount for that fleet. That is the fleet in the third sea region away from the pot will cost 3x its base maint. cost.

The AI will get a province in the middle decreasing the costs of his trade vessels.

Unfortunately trade vessels cost ridiculusly little to maintain and so one or the AI can get millions of income if holding the right provinces. This can be addressed effectively by getting the base maint. cost for castal vessels to about 55 florins.

I am sure that trade goods and agr income comes into the equation for the AI to choose the province he wishes to colonise. For example the Spanish will often target Flanders for their naval invasions.

[gaiusjulii]

The only time I ever see the AI do naval Invasions is the sicilians and they often try for scotland and crusades but I dont think this is intentional on behalf of the AI.... but What I wanted to input into this convo was that why does the AI start stupid wars? I was recently playing as the english, the french were wiped out and I was allied to HRE and the HRE was at war with no one else. Now boom the HRE invade and break the alliance, they had no chance of winning so why start the war and for no reason? I have noticed that even if the AI regardless of faction is at peace with everyone It will usually pick a war at least 2 fronts at the same time and in most case's lose.... is the AI programmed for self destruction? and/or for certain factions?

[Noir]

It is beyond any doubt that the AI intentionaly does naval invasions and all AI factions can do so; the probabilities increase with the size of their trade network. They are not always to their best interests in the long term, but almost half the time they are. I have playtested this more than once by autorunning campaigns.

The AI factions behave reasonably in the hard level assuming, that you are ransoming back prisoners regularly and you do not doublcross too much. The AI does have a "memory" and holds a grudge to cruel leaders/doublecrossers or to those that are at war with many or with those that are too large, and also will start a war almost for the sake of starting it at expert, i find.

Many players dont realise that being the size of France and England means in the eyes of the AI that its now or never as there's little stopping the player being the dominant faction. Another thing that results in this is that the upkeep and rebelliousness are way too small - the AI in vanilla regularly abandones provinces and moves ALL his forces to the border he intends to expand. This is not the case if provinces have a 1 or 2 rebelliousness. Then the AI garrissons his provinces and plays much better as his territories have robustness. The same is true for the player that has to deal with the risks of being unable to garrison effectively a newly conquered province and the one from which he launched the invasion.

Also play at hard. It is the most fair level anyway for both the player and the AI, be it in the battles or the campaigns. In expert the AI is out to get you and the battles are unfair to the point of stupidity.

[Deus ret.]

but What I wanted to input into this convo was that why does the AI start stupid wars? (...) is the AI programmed for self destruction? and/or for certain factions?

I'm afraid the best answer I can give to this is the one Cambyses II gave some way up this thread: The AI is a simple beast. Don't count on it to be rational more often than occasionally.

@Noir: I'm pretty sure the AI has no such thing as a memory. The entire diplomacy system reflects this, one turn they start an all-out war and the next they offer peace, without having achieved or lost anything substantially. The AI's behavior towards the player is indeed influenced by certain factors, among them empire size and faction choice (Byz and esp. HRE are less liked), but as far as I can tell there seems to be no real influence of the players' past actions.

[Noir]

Originally posted by Deus.Ret
@Noir: I'm pretty sure the AI has no such thing as a memory. The entire diplomacy system reflects this, one turn they start an all-out war and the next they offer peace, without having achieved or lost anything substantially. The AI's behavior towards the player is indeed influenced by certain factors, among them empire size and faction choice (Byz and esp. HRE are less liked), but as far as I can tell there seems to be no real influence of the players' past actions.

Allow me to disagree,

i played several campaigns that after a war with a faction that ends usually in a border rearrangement, and very rarely in total anhihilation, past a number of turns that the AI holds a "grudge" - "suspicion" will accept peace or even sue for peace.

Several times prior to "razing" the main facilities of a faction i had a bitter feud with, i was offered peace obviously in order to save them.

And when i behave like a total clandestine, starting wars,slaughterning prisoners, never helping allies, always doublecrossing, then yes the AI drops all diplomacy and goes after me as he sees fit.

For all intends and purposes such a memory exists as far as i am concerned, and the diplomatic system almost works as long as you treat the AI factions as diplomatic entities and not as pushovers on the way to the top, especially if the AI is not constantly at the verge of bankruptcy or constantly spurred to become bigger like as it happens in vanilla and many mods.

I should note that other players have also posted signs of such suspicion here and at the .com were i used to frequent.

Noir

[Noir]

May i also add,
that in many occasions "inexplicable" AI actions/aggression are actually very easy to understand if one can see all the map (with the .matteosartori. cheat). For example a suddenly very aggressive HRE on the west may be losing a war in the east, muchlike the Unknown Guy and Cambyses II describe in order to get breathing space and fight back on that front.

Or you just happen to be the obstacle in your neighbours expansion, this usually means that you'll have to fight till they are thoroughly defeated (but not necessarily anhihilated).

In any case, global conditions also influence AI behaviour to my understanding.

[caravel]

I am not convinced that the AI somehow decides to invade a province over seas. In my experience the AI is very random illogical in it's deployment of ships. If the AI's vessels happened to form an unbroken line from e.g. Egypt to Valencia, the the AI, having no sense of distance in such cases, will regard that as a direct landbridge, and simply invade conditions permitting. Egypt will go for Cyprus because they only have to build one ship and their armies will be able to get there. As soon as the ship is built the AI regards it as a direct route and will invade. There is no planning, it is purely reactionary and on a per turn basis. It is perhaps to the game designers' credit that such a simple AI can at times have the appearance of being something deeper and more strategic.

When a faction is attacked on one front, several things may occur.

1) The faction may change AI type as a result of the war. This may make the faction much more warlike.

2) The faction will lose alliances with other factions possibly causing war with neighbours.

3) Losing a province places the defeated army and randomed units in another province, possibly overloading that province. The AI will then consider using those men to invade a neighbour. The AI spreads out quickly if it has very large stacks in a small number of provinces.

I am not convinced that the AI invades purely for economic reasons, as the Danes and Aragonese wait an age before going for neighbouring provinces - if ever, while their economies stagnate. If it was economic based they would make a desperate invasion attempt once their economies had gone into the red.

[Deus ret.]

Of course you may differ!

In any case, global conditions also influence AI behaviour to my understanding.

Very true. As I stated above, there are quite a number of factors influencing the AI. It's just that they have nothing to do with memory. You mention 'suspicion' of yours and others in the post above the one I quoted - signifying that there is no evidence, just an assessment of the AI's behavior. I've played the game sufficiently long to reach the conclusion that the AI is definitely competitive, but also that its actions are *not* influenced by player actions in the past.

A breach of alliance on the player's side may well result in the AI offering or accepting another one within ten years. Not even the most chivalrous behavior will influence that, as it doesn't matter whether you destroy entire provinces of the rival faction or whether you hand them the province over in an improved state. The same counts for the conduct with prisoners. I once thought similar to the way you described but in the end I found the AI's reactions to be too random to be responsive to my own deeds.

[gaiusjulii]

I have to agree with Deusret as I have been a model knight and very chivalric in the past by not taking the offensive and not invading any other provinces yet still the AI has from time to time either slaughtered or given me a break...... just plain irrational

[Caerfanan]

I have on occasion had the exact opposite experience. Can't recall the factions/provinces involved but I got to a point in one game where an overwhelming invasion occured. I reloaded, increased my garrison, and the AI invasion was larger. Same again, even bigger. In the end I decided the province was undefendable, so reduced the garrison to just enough to maintain loyalty. Guess what? The AI didn't invade, and indeed that entire war never happened! So in some circumstances it seems that a more heavily defended province can be MORE of a temptation to the AI that an effectively undefended one. It might be down to the fact that the AI couldn't "see" what armies I might have had in a potential "counterattack province", or maybe my border garrison was a "provocation" to it.

I've figured that having a heavily garrisoned border makes your neighbours nervous, and might give them the want to strike the first blow.

[Noir]

I say that it is a "suspicion" as i can't (and don't have to) convince you for the truth of my conviction and neither can you of yours as your main argument is extensive experience. However i need to respect your opinion, much like you are respecting mine so we can have the very nice conversation we are having about our soft spot Deus.Ret.

For what Cambyses II comments, i'll say that the AI certainly did take account of the maintenance cost of its boats in building his trade network while i was playtesting campaigns in my home mod where the fleets cost apprx. 50-60 flrns to maintain each, in every campaign. I have observed this, as well as the fact that the AI would wait to make a port in a province before deploying a fleet there in order to trade if he has the chance. His invasions were always aimed at provinces that would decrease significantly the maintenance costs he was getting ie in the middle or the other end of the trade "line". His tendency to do so was increased as i mentioned by the amount of money he was getting by the trade; if he was succesful he would definitely invade - first rebels and if not available eventually someone else.

For these i am certain beyond any doubt, i've seen it happening in every campaign i've playtested. I can pass you on the files of my alteration of MedMod IV so you can run test campaigns your self, if you (or anyone else) wishes. Its also easy to observe, because there are few fleets that do not aimlessly hanging around in all seas like in vanilla due to the maintanance cost and because of the basin separation i've told you in another occasion Cambyses II.

If the AI actually does this because the cost is so high, i don't know (and so it does act more at his "free will" because he can afford to in vanilla). However, i can tell you that even if the latter is true, it proves that the AI is capable of good play consciously to a certain extent on his way to become huge.

Once he gets huge he overextends and blows off by himself and i believe this is hardcoded.

For the AI invading for economic reasons - they are not pure i agree, however they seem to be included in the equation, when doing invasions, and also when Crusading. It is incredible that Egypt or Algeria are the targets of Crusades 95% of the time in my games - as they are the more lucrative ecomonically provinces in muslim lands.

The factions you mention stagnate because the AI factions find it risky to invade - its not like they can afford to lose as they will be anhihilated. Surprisingly, enough the AI does care to stay in the game, and as i said earlier factions that are beaten severely and "sense" anhihilation, will sue for peace. I've seen that happening and read about it many times. It is also happening in the SWs mod, that almost every faction is in the state of the Aragonese, including the player. The AI personality of them in the mod is set to "expansionist" for all. They take ages to take off though, because they are cautious as they are all surrounded by enemies. Things may go wrong, and the Ai aknowledges that. Apparently it has a certain threashold embedded for invading and until that is reached he won't do it or he will invade with very few troops - this is mentioned in the files as "opportunistic attack" ie its not a full scale effort but more on the basis of "see if we can exploit that gap".

The Serbs, a similar case as the ones you mention in my home mod of MedMod IV, wait for the right conditions around them to invade. Where the game is wrong is in the buidling costs and building flow as well as the bodyguard maintanance costs that prevent the AI to be close to the green, economically. If the military buildings didn't take an age and cost a fortune for the AI to build as he goes on to complete the forts and then start by building them all one by one, you'd see that when he does makes a move from the 1 province faction state, he can actually come on top if not bunkrupt.

"Idiotic" attacks from the part of the AI, as it was mentioned by The Unknown Guy and Cambyses II, mean economic health and also thus, the chance to get the newer units. The AI initially, especially in vanilla,spams armies of very low tech troops, in order to deter others from invading. However these cost him dearly. For the player its easy: slowly disband and then make the better ones, but the AI can't do that. He has to get rid of them by making war. So he invades with inferior troops, raising the palyer's eyebrows in the mean time. However for him this is the way to progress, as he can have positive net again and so build the newer/better units. This is why i haven't touched vanilla for a long time now, as the difference between the units in eras is huge - essentially a battle winner, but the AI doen't have a chance in keeping up building them like the player does hence the hardcoding of building all military upgrdades first. This means that he neglects the economy ending up in the red for most faction apart from the fortunate few that are destined to become huge so the player has something to do.

All in all its simply bad design, that was introduce to make the campaign "deeper" also read "more conventional RTS". Now of course after RTW, it seems like a "harmless vice".

The game's tech/build tree accounts for the player only but not how the AI does things, and this makes him look stupid. Of course he is, but i think much less than most of us think. What the game really needs to become challenging throughout its length, is a smoothing of the spending flow and income of the AI factions and also ensurance that this flow remains constant together with balanced rosters. For example the Ai doesn't use hybrid units effectively - he never uses them in melee. The very fact that they exist is a spoiler as they are there just for the player.

Noir

PS Apologies for playing the "odd" man in this, it happened unintentionally.