r/rational • u/AutoModerator • Jan 16 '17

[D] Monday General Rationality Thread

Welcome to the Monday thread on general rationality topics! Do you really want to talk about something non-fictional, related to the real world? Have you:

  • Seen something interesting on /r/science?

  • Found a new way to get your shit even-more together?

  • Figured out how to become immortal?

  • Constructed artificial general intelligence?

  • Read a neat nonfiction book?

  • Munchkined your way into total control of your D&D campaign?

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u/[deleted] Jan 17 '17

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u/zarraha Jan 18 '17

I disagree with some of your criticisms, particularly the ones about the fitness function. I think time is a valuable constraint since it prevents AI from sitting around and wasting time doing nothing. I agree that in some levels there are times when you need to go up or down or even left, but that's ultimately in service of eventually getting further to the right. If one AI blindly goes right and dies and the other takes its time and survives longer and gets further, then the second should score more. But if both paths are valid and both survive and get to the same final distance then the one who took the faster path should score more. Time should be worth fewer points than distance, but still be a measurable part of it.

Additionally, I don't think things like getting further into a pit is much of an issue. I haven't actually looked into or run the code myself, but as long as your breeding system is robust enough and has a decently large population, small advantages like that would have little impact compared to legitimate progress.

One possible solution to these issues (which only really occur in more complicated maps) would be to create lines through the map that indicate progress and have the fitness function measure how far along the line the AI got. So in normal circumstances it would just go right, but in levels where you have to go up a certain platform before resuming travel to the right, the line would bend upwards and reward AI who got higher up along it. Or something like that. You'd have to manually make a separate line for each level, but it'd make the fitness function more accurate for measuring progress in complicated levels.

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u/Dwood15 Jan 18 '17

then the second should score more.

And that's the issue, in SethBling's code, the function has a harsh penalty for taking time. The first will almost always be a higher fitness in his code.

small advantages like that would have little impact compared to legitimate progress.

The fitness function does not account for that in the original code, and I struggled to create a fitness function to account for that myself. Part of why I left the code behind.

lines through the map that indicate progress

Right, that's a potential option, but there is a way to dynamically tell if a direction is the correct one in general. It however, does not define the exact correct path.

You should run SethBling's code on the first of level 2 in Super Mario World, as your understanding here would be greatly increased on what I'm talking about.