Well, not really. Training a model is one such task. It's hard to train a network but easy to verify that it has good performance (training vs inference). The

Well, not really. Training a model is one such task. It's hard to train a network but easy to verify that it has good performance (training vs inference). The real problem here, I believe, and I've seen this idea pop up several times on hackernews, is that almost no machine learning tasks are progress free. If the cryptocurrency is just paid out to the person who solves the task first in a non-progress free problem, then the person with the fastest GPU would mine all the coins and nobody else can participate. One of the key ideas behind proof of work is that if two people have the same compute, and person A has a headstart, if person A has not succeeded by the time person B starts, they'll have the same probability of mining a block. People seem to be just jumping on the crypto bandwagon and trying to come up with "useful" proof of work, but it's a pretty difficult task.