zlacker

I’m wondering what PDDL is for, in practical terms.

Planning, yes, but that’s a verb that casts a very wide net.

When might one write PDDL? Be it specific tasks, or industries it is used in - the examples I’ve found online all have a robotic theme, yet the idea seems much more general.

What do they do with it once they’ve written it?

What does it solve (as opposed to just having the existence of a file that outlines objects, predicates, actions etc)?

>>i-use-+(OP)
It feels like one of those things that would be really interesting to just throw into the wild and see what comes of it. It's kind of hard to hypothesize with these things when the horizon of possibilities is so wide and the level of understanding is relatively low (compared to the model's perceived capabilities).

>>i-use-+(OP)
PDDL files do outline objects, predicates, actions, etc. in a machine-readable way, but in a much more expressive manner than can be done with something like JSON.

PDDL is designed to be machine readable, but also human-readable and writable. I would say you would write PDDL when you want to provide a description of the rules of a domain to an algorithm that does automated planning and acting. This could be an autonomous agent of any sort, doesn't necessarily have to be embodied/robotic in nature.

>>i-use-+(OP)
>> Planning, yes, but that’s a verb that casts a very wide net.

The article uses "planning" to mean "classical planning", which is a very specific thing, although it's such a fundamental concept in AI research that it is very difficult to find a simple definition (there's a lot of useless stuff on the internet about it, like tutorials that don't explain what it is they're tutorial-ing, or slides that don't give much context).

Even the Wikipedia article is not very well written. I followed this link to one of its references though and there's an entire textbook, available as a free pdf:

https://projects.laas.fr/planning/

In general, classical planning is one of those domains where GOFAI approaches continue to dominate over nouveau AI, statistical machine learning-based approaches. You'll have to take my word for that, though, because that's what I know from experience, and I don't have any references to back that up. On the other hand, if it wasn't the case, you wouldn't see papers like the one linked above, I suppose.

To clarify, the paper above makes it clear that LLMs, for one, are useless for planning but at least they can translate between natural language and PDDL, so that a planning problem can be handed off to a classical planning engine, that can actually do the job. How useful is that, I don't know. A human expert would probably do a better job of writing PDDL from scratch, but that's never explored in the linked article.