This member is added by an implicit conversion from Reduction_[P, S] to
any2stringadd[Reduction_[P, S]] performed by method any2stringadd in scala.Predef.
This member is added by an implicit conversion from Reduction_[P, S] to
StringFormat[Reduction_[P, S]] performed by method StringFormat in scala.Predef.
A reduction that does not change the type of the problem.