[ape_key]

(a+b)-a doesn’t always equal (a-a)+b

It’s different behavior if the order of operations are non-deterministic.

Plenty of room for such things in games. Most of the time the effects are too small to notice. They can chaos-theory out of control, though.

So real time games nearly universally sync state instead of relying on deterministic synchronization via events/actions.

For a good read, look up lockstep deterministic networking.

There’s way too much nuance here to be so dismissive

[bowsamic]

Chaotic behaviour is deterministic

[ape_key]

Weird how I write complete thoughts and supply references but this site full of tech geniuses mostly produces downvotes and single-sentence drivebys.

Come back when you have things worth contributing.

[bowsamic]

I’m a theoretical physicist, not a tech genius. Perhaps that’s the mode matching problem here. I don’t trust your 23 hour old account though :)

[thaumasiotes]

> I don’t trust your 23 hour old account though :)

This might explain why you aren't a genius. He's not saying anything that hasn't been featured on HN before.

This is a popular article: https://www.gamedeveloper.com/programming/1500-archers-on-a-...

It details how Age of Empires decided to make the game deterministic, how this had significant benefits, and how it's extremely difficult to do:

> At first take it might seem that getting two pieces of identical code to run the same should be fairly easy and straightforward -- not so. The Microsoft product manager, Tim Znamenacek, told Mark early on, "In every project, there is one stubborn bug that goes all the way to the wire -- I think out-of-sync is going to be it." He was right. The difficulty with finding out-of-sync errors is that very subtle differences would multiply over time. A deer slightly out of alignment when the random map was created would forage slightly differently -- and minutes later a villager would path a tiny bit off, or miss with his spear and take home no meat.

Do you think you look good by announcing that, since you don't know the subject you're discussing, you're not going to trust someone who does?

[bowsamic]

I don't trust new accounts whose instinct is to insult me. I don't need to justify that heuristic. Also I was right, chaotic behaviour doesn't mean non-deterministic, which the quote you posted affirms.

So not only was I insulted, I was insulted even though I was right. Also I have studied chaotic dynamical systems, so I have formal education in this.

The interesting thing about chaotic systems is that they have very divergent futures for very similar inputs, not that they're random.

Also I don't really care about being considered a genius, and I think it's sad that anyone would want to be thought of as one.

[thaumasiotes]

Saying stupid things is pretty likely to draw insults. They were obviously warranted here.

> The interesting thing about chaotic systems is that they have very divergent futures for very similar inputs, not that they're random.

If you were paying attention... that's exactly what ape_key was referring to. The problem under discussion is that very similar inputs to the game logic lead to radically different states of the game at a later time. The nondeterminism is what gives rise to the fact that the inputs are "very similar" rather than "identical".