Sharing is harder than agreeing
Carole Delporte-Gallet, Hugues Fauconnier, Rachid Guerraoui · 2008
One of the most celebrated results of the theory of distributed computing is the impossibility, in an asynchronous system of n processes that communicate through shared memory registers, to solve the set agreement problem where the processes need to decide on up to n-1 among their n initial values. In short, the result indicates that the register abstraction is too weak to implement the set agreement one.