Sorry for this very very late answer. I'm the author for this paper, my name is Julio Moros. I'm from Caracas, Venezuela. And all this time I've been too busy just to earn my living here.

But, let me answer your question: Proof of Labor was a research proposal exposed to Dash masternodes in one of their budget proposals. Such proposal was sadly declined.

First of all: My vision those days was that Dash had the full potential to become in any thing they want (they can do it still today). Today I know that sadly Dash proposals are more orientated for a marketing promotion of Dash, than anything else.

Second: I had to keep my vision by myself, and doing my own research. Proof of Labor is a proposal for an alternatively money system in which money can be created in such a way it does not create inflation, and in such way that the production which backs any value in the system is verified by some decentralized system.

Today I know that such systems are ORACLES. There are two main types of oracles: machine-oracles, and user-oracles. The oracles faces two major flaws which the state of the art hasn't completely solved yet. These are the freeloader dilemma for machine oracles, and the bribe attack for user oracles.

We are very close to solve both problems. The freeloader dilemma has been addressed very well by oracles like Chainlink, Kyber or 0x. But the bribe attack is a little more complicated. I'm very confident that in the next few months a solution will emerge and this kind of money systems will start to be commercially avalilable.

Thanks for your question.