  A distributed proof (also known as local certification, or proof-labeling
scheme) is a mechanism to certify that the solution to a graph problem is
correct. It takes the form of an assignment of labels to the nodes, that can be
checked locally. There exists such a proof for the minimum spanning tree
problem, using $O(\log n \log W)$ bit labels (where $n$ is the number of nodes
in the graph, and $W$ is the largest weight of an edge). This is due to Korman
and Kutten who describe it in concise and formal manner in [Korman and Kutten
07]. In this note, we propose a more intuitive description of the result, as
well as a gentle introduction to the problem.
