I believe the point in 'slowing'/'not-slowing', is that while we are still talking about 'games' and beating humans, the games that are being tackled are getting more complex in each iteration, solving new problems.
And DeepMind did go off and tackle increasingly complex areas in other fields.
Not sure how anyone can argue AI slowed down. Maybe advancements in one particular game slowed down, but was that because they hit a wall? or because they shifted company resources after a game demo.
I'm not sure how you are measuring time, do you think that because AlphaStar was a few years ago, that means AI advancement slowed down? Because there wasn't another breakthrough in AlphaStar? Because they didn't keep going and fully build out every race and unit?
Do you think DeepMind has been throwing resources at Star Craft and just hitting a brick wall?
It was a proof of concept, they beat some humans, and moved on to other things like Protein Folding. Was the Protein Folding not impressive enough to think AI was still advancing?
AI is continuing to advance, because for each iteration it is tackling bigger, more complex, problems.
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The time between each breakthrough does seem to be a down line, less time between each plateau.
Chess : Board with a lot of possible moves, but 'manageable', the AI could just calculate every move.
GO: More possible moves than atoms in the universe or something. So the AI had to use some form of 'intuition', it could no longer brute force calculate every move. (it was only few months after AlphaGO won that they turned the same engine on Chess and it 'learned' from scratch to be a Master in only a few hours.)
SC2: There are no 'moves' it is all real time movement, and most important, there as imperfect information. The AI had to scout and keep track of un-known positions, to remember and anticipate.
Dota: Honestly, I'm not sure what the big breakthrough is for Dota. But quibbling over how many 'hero's the AI had access to seems pedantic. Wasn't this years ago. This isn't a knock on AI, the Dota work was years ago. We're arguing about an AI that is 3+ years old now. I really don't think that you can say AI research slowed because a company stopped throwing money at a game demo.
Protein Folding: Hey, lets stop just focusing on games and do something to help the world.
Poker: Wasn't Poker also conquered in this time frame, in last 2 years? Showing ability to bluff?
3D Virtual Environment: Was in discussion in another thread where everyone's main argument was AI isn't 'embodied' in the 'world', doesn't 'live' in the 'world'. And boom, same day, another breakthrough covering that. Giving machine what we would call 'vision', to understand objects in the world.
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Now slap this into a robot, give it a gun, and tell it the world is a 3d game.
LOL.
"We haven't had a miracle in the last 6 months, oh no, AI advancement is slowing down."