  We review and explain an infinite-dimensional counterpart of the Hurwitz
theory realization of algebraic open-closed string model a la Moore and
Lizaroiu, where the closed and open sectors are represented by conjugation
classes of permutations and the pairs of permutations, i.e. by the algebra of
Young diagrams and bipartite graphes respectively. An intriguing feature of
this Hurwitz string model is coexistence of two different multiplications,
reflecting the deep interrelation between the theory of symmetric and linear
groups S_\infty and GL(\infty).
