These sorts of papers would be a little easier to read if the definitions were a little tighter and the goal of the article was a little clearer. "Marketplace"

These sorts of papers would be a little easier to read if the definitions were a little tighter and the goal of the article was a little clearer. "Marketplace" & "trust" are big-ish words, for example. I'm still not sure what the "The challenge of decentralized marketplaces" is. Securing reputation systems against spam? What's all the stuff about different market types for?