Looking the graph below, what type of an attack is this likely?

A proof of work system is vulnerable to a particular type of attack called the “P+ epsilon attack”. In order to understand how this attack works we must define some terms before hand. Un-Coordinated Choice Model: An uncoordinated choice model is a model where all the participants don’t have the incentive to work with one another. The participants may form groups but at no time is the group big enough to become a majority.