Computing the longest topological common subsequence of a symbol-wise totally ordered directed acyclic graph and a sequence

Let G be a directed acyclic graph, each vertex of which is labeled with a symbol, and having, for any such symbol, a path in which all of the vertices labeled with the symbol appear with vertices labeled with other symbols. Let B be a sequence of symbols. This article proposes a polynomial-time algorithm for computing one of the longest possible common subsequences of a sequence specified by any topological sort of G and the sequence B.