Efficient Methods for a Life Simulation

Question

Having read up on quite a few articles on Artificial Life (A subject I find very interesting) along with several questions right here on SO, I've begun to toy with the idea of designing a (Very, very, very) simple simulator. No graphics required, even. If I've overlooked a question, please feel free to point it out to me.

Like I said, this will hardly be a Sims level simulation. I believe it will barely reach "acceptable freeware" level, it is simply a learning exercise and something to keep my skills up during a break. The basic premise is that a generic person is created. No name, height or anything like that (Like I said, simple), the only real thing it will receive is a list of "associations" and generic "use", "pick up" and "look" abilities.

My first question is in regards to the associations. What does SO recommend as an efficient way to handle such things? I was thinking a multimap, with the relatively easy set up of the key being what it wants (Food, eat, rest, et cetera) and the other bit (Sorry, my mind has lapsed) being what it associates with that need.

For example, say we have a fridge. The fridge contains food (Just a generic base object). Initially the person doesn't associate fridge with food, but it does associate food with hunger. So when its hunger grows it begins to arbitrarily look for food. If no food is within reach it "uses" objects to find food. Since it has no known associations with food it uses things willy-nilly (Probably looking for the nearest object and expanding out). Once it uses/opens the fridge it sees food, making the connection (Read: inserting the pair "food, fridge") that the fridge contains food.

Now, I realise this will be far more complex than it appears, and I'm prepared to hammer it out. The question is, would a multimap be suitable for a (Possibly) exponentially expanding list of associations? If not, what would be?

The second question I have is probably far easier. Simply put, would a generic object/item interface be suitable for most any item? In other words, would a generic "use" interface work for what I intend? I don't think I'm explaining this well.

Anyway, any comments are appreciated.

Answer 1

To the first question:

My understanding is that you have one-to-possibly-many relationship. So yes, a multimap seems appropriate to me.

To the second question:

Yes, I believe a generic interface for objects is appropriate. Perhaps use something similar to REST to manipulate object state.

Answer 2

Life with lisp(sbcl) :)

Answer 3

If you were doing this as a hard-core development project, I'd suggest using the equivalent of Java reflection (substitute the language of your choice there). If you want to do a toy project as a starter effort, I'd suggest at least rolling your own simple version of reflection, per the following rationale.

Each artifact in your environment offers certain capabilities. A simple model of that fact is to ask what "verbs" are applicable to each object your virtual character encounters (including possible dependence on the current state of that object). For instance, your character can "open" a refrigerator, a box of cereal, or a book, provided that each of them is in a "closed" state. Once a book is opened, your character can read it or close it. Once a refrigerator is opened, your character can "look-in" it to get a list of visible contents, can remove an object from it, put an object in it, etc.

The point is that a typical situation might involve your character looking around to see what is visible, querying an object to determine its current state or what can be done with it (i.e. "what-state" and "what-can-i-do" are general verbs applicable to all objects), and then use knowledge about its current state, the state of the object, and the verb list for that object to try doing various things.

By implementing a set of positive and negative feedback, over time your character can "learn" under what circumstances it should or should not engage in different behaviors. (You could obviously make this simulation interactive by having it ask the user to participate in providing feedback.)

The above is just a sketch, but perhaps it can give you some interesting ideas to play with. Have fun! ;-)

Answer 4

I heard a podcast a while back with the developer of The Noble Ape Simulation, which may be interesting to you - conceptwise and perhaps codewise, as you can access the source code, as well as download binaries.

The podcast was FLOSS Weekly 31 with Randal Schwartz and Leo Laporte.