  Introduced by Korman, Kutten, and Peleg (Distributed Computing 2005), a
\emph{proof labeling scheme (PLS)} is a system dedicated to verifying that a
given configuration graph satisfies a certain property.
  It is composed of a centralized \emph{prover}, whose role is to generate a
proof for yes-instances in the form of an assignment of labels to the nodes,
and a distributed \emph{verifier}, whose role is to verify the validity of the
proof by local means and accept it if and only if the property is satisfied.
  To overcome lower bounds on the label size of PLSs for certain graph
properties, Censor-Hillel, Paz, and Perry (SIROCCO 2017) introduced the notion
of an \emph{approximate proof labeling scheme (APLS)} that allows the verifier
to accept also some no-instances as long as they are not "too far" from
satisfying the property.
