Two components of the boundary of \(\text \textbf{I}_3\). (Deux composantes du bord de \(\text \textbf{I}_3\)) Mirror symmetry and rational curves on quintic threefolds: A guide for mathematicians. Appendix A: Proofs of the monodromy lemmas. Appendix B: Resolution of certain quotient singularities. Appendix C: The monodromy of the quintic-mirrors 