2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/72443Extended Alexander groups are used to define an invariant for open virtual strings. Examples of non-commuting open strings and a ribbon-concordance obstruction are given. An example is given of a slice virtual open string that is not ribbon. Definitions are extended to open n-strings.9 pages, 10 figures. Version 2 includes improvements to section 3. To appear in J. Knot Theory and its RamificationsGeometric TopologyPrimary 57M25; secondary 20F05, 20F34text