2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/53523We review the basics of the dynamics of closed strings moving along the discretized line \Z. The string excitations are described by a field ϕ_x(τ) where x is the position of the string in the embedding space and τis a semi-infinite ``euclidean time'' parameter related to the longitudinal mode of the string. Interactions due to splitting and joining of closed strings are taken into account by a local potential and occur only along the edge τ=0 of the semi-plane (x, τ).12 pages, harvmac , SPhT/93-038 (Lecture delivered at the 4th Hellenic School on Elementary Particle Physics, Corfu, 2-20 September 1992)High Energy Physics - Theorytext