Hacker News Reader

Comment by gwnywg | Hacker News Reader

I find it weird to see people calling A* an 'AI technique'... Is BFS or DFS an AI technique too? I thought it's merely a search algorithm...

View on HN

When it was published, A* was considered within the field of AI. The paper[0]'s authors were from Stanford's AI group.

The "AI effect"[1] describes how the field tends to get left with only the cutting-edge research.

[0]: http://ai.stanford.edu/~nilsson/OnlinePubs-Nils/PublishedPap...

[1]: https://en.wikipedia.org/wiki/AI_effect

By way of [1], here [2] is a paper about A* also posted under CS/AI. It introduces "Q* search, a search algorithm that uses deep Q-networks to guide search" and uses it "to solve the Rubik's cube", the thing which Gary Marcus complained about OpenAI not having done with a neural network in 2019.

As pointed out by techbro92 [3] the authors do not seem to be affiliated with OpenAI, but AFAIK nobody claimed that OpenAI invented Q*. It's not hard to imagine OpenAI trying it out with their Rubik-solving robot hand and then starting to think about other things it might be applied to.

[1] https://news.ycombinator.com/item?id=38395959

[2] https://arxiv.org/abs/2102.04518

[3] https://news.ycombinator.com/item?id=38398243

I still think the "AI effect" is bullshit. A* was/is AI under a different meaning - it's what understood as "AI" in computer games, where the point is for the computer opponent to pretend to be smarter than a brick, and literally any trick, cheat or heuristic used to do that is part of "AI". A*? Obviously AI. Random walk? Yes. Fuzzy logic? Yes. State machines? Yes.

True that A* would later go on to be used in computer game bots (as LLMs may eventually be) where "an AI" doesn't necessarily correspond to the field of AI, but A* was still within what was understood to be the field of AI at the time it was published.

The meaning shifting over time, and the reason for which it shifts, is the AI effect. Heuristic-guided pathfinding is no longer what's meant by AI, IBM Deep Blue's alpha–beta search is no longer what's meant by AI, and I'd claim it's even shifting away from earlier image classifiers in favor of only generative models like GPT4.

There's no magic in 'AI', all of it can be described as something else. The whole of ML is 'just statistics', especially classification.

(That said I was and I suppose am a bit of a sceptic because of that. But mainly I think because to me it's more useful to call a spade a spade and say we're doing some advanced blah stats to blah. Helps explain, onboard, and motivate the next generation (who likes stats at school? But if that's how AI works, oh suddenly it's cool). Demystify it. If you're just searching over Levenshtein distance [to a technical audience] say that, don't start waffling about 'AI'.)

Yes,ultimately everything is just a bunch of ifs. Wired together in a very complicated fashion but ultimately a bunch of ifs.

I first learned it in the famous book "Artificial Intelligence: A Modern Approach" by Peter Norvig. I think 3 chapters are dedicated to search. A lot of AI can be framed as search, and a whole lot of historical AI, or mundane present AI, is straightforward search.

Search is 100% key to AI, even historically. Prolog has its roots in AI research, and Prolog evaluation is a form of unification, which is a search.

AI is the cutting edge of CS. When it's well understood it stops being AI. Some day LLM and neural nets will get the same reaction... who calls LLM "AI"? It's just a formula!

Quite. One of the best uses I've seen for LLMs is for NPC dialog in computer games.

What games are using that?

Vaudeville

Is it really though? I feel like it's mostly non-technical people who think this, because back when I was a CS student, AI was just a big field of study that included many types of problem solving, from simple to complex, including all types of search such as A*.

Probably because of A*'s popularity for path finding in game development. Everything that imitates human-like behaviour in games is called "AI", even when most of it is just a big messy hairball of adhoc if-else code under the hood ;)

I think (probabilistic) logic programming also relies on graph traversal/path searching, which is part of the symbolic AI paradigm.

Most likely for historical reasons where A* was used alot in games path finding for in-game AI characters

Linear regression is AI.

Reply on news.ycombinator.com