3 ms·

The puzzle overstates the importance of figuring out the protocol in practical applications. Why does it matter whether or not you are in a 2:2 case versus a 3:

The puzzle overstates the importance of figuring out the protocol in practical applications. Why does it matter whether or not you are in a 2:2 case versus a 3:1 case in something like games (their example)? The problem of networked games isn't strictly timing. The actual problem is the illusion of real time play. We want networked players to feel like everything is happening in real time. But their changes to the shared world might, due to latency, be mutually incompatible. The puzzle is not making a system that is accurate—that's trivial (it involves a lot of waiting). The puzzle is making a system that appears to be in real time.

Strilanc 14y ago
If there was a way to distinguish 2:2 from 3:1, it would affect how networked games played out. It would affect how ordering violations were resolved, which is pretty important in games ("Did I block before that punch landed?"). It so happens that the cases can't be distinguished, so it "doesn't matter". As an analogy, what would the world be like if the speed of light wasn't invariant with respect to velocity? It happens to "not matter" because the speed of light is invariant in that way, but it's still an interesting question.
- doctorpangloss 14y ago
  It certainly matters to adjudication. But perhaps the question players care about is not quite, "Did I block before that punch landed?" (a very important question), but, "I just blocked, but he hit me for some reason anyway." That is to say, players get upset (1) if something seems to violate their own worldview, due to adjudication. Naively, we could solve that case by running the timesteps of the simulation slower than the greatest latency (or more accurately, when heartbeats from all players have been received for a given timestep). That would introduce us to another reason players get upset: (2) if the game is really laggy. I'm glad you bring up relativity as an example. The best method games have for improving the real-time illusion is locality.

Strilanc 14y ago

If there was a way to distinguish 2:2 from 3:1, it would affect how networked games played out. It would affect how ordering violations were resolved, which is pretty important in games ("Did I block before that punch landed?"). It so happens that the cases can't be distinguished, so it "doesn't matter". As an analogy, what would the world be like if the speed of light wasn't invariant with respect to velocity? It happens to "not matter" because the speed of light is invariant in that way, but it's still an interesting question.

doctorpangloss 14y ago
It certainly matters to adjudication. But perhaps the question players care about is not quite, "Did I block before that punch landed?" (a very important question), but, "I just blocked, but he hit me for some reason anyway." That is to say, players get upset (1) if something seems to violate their own worldview, due to adjudication. Naively, we could solve that case by running the timesteps of the simulation slower than the greatest latency (or more accurately, when heartbeats from all players have been received for a given timestep). That would introduce us to another reason players get upset: (2) if the game is really laggy. I'm glad you bring up relativity as an example. The best method games have for improving the real-time illusion is locality.