In a major AI system is more likely to be driven by data, not by code. Rather than complex If/Else trees it is more likely to be handled by an array of conditions, and the conditions are actually objects derived off a basic state class. The programmer would create the framework for the rules. The designers would likely have either a spreadsheet or a tool that lets them enter whatever data fields they want. During the game load process the data would end up loading that data and creating whatever data-driven implementation the designers want.
If you have a copy of Final Fantasy 12 available, their AI system is completely exposed to the player. If you don't have a copy of the game available, the Wikipedia article describes it as the AI "consists of three parts: a target, an action, and a priority. The target specifies which ally or foe to act on and the condition for applying the action. For example, the target "Ally: HP < 70%" causes the character to target any ally whose hit points have fallen below 70%. The action is the command to be performed on the target. The priority order determines which action to perform when multiple actions are triggered."
Can you expand a little bit more on 'driven by data' thing? Because I still see this as IF-THEN (or Switch).
I mean, we have a class that gathers information and spits out data like how much health does a bot have, how many enemies are around, whats in the bot's inventory, etc. And then we operate with this data to make the bot do some action, for instance, if he has low health and if he has Health Potion in the inventory, he drinks it.
Visit www.edx.org and checkout the AI online course (Starts 18th Feb and it is free). It should give you an idea if you like it or not.
Eh, they ask for quite good math knowledge. I finished my formal education like 8 years ago and now am relearning math and steamrolling through it, but I don't have that high level yet. And yes, I know that AI is all about math.