2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/59719The notion of a virtual knot introduced by L. Kauffman induces the notion of a virtual braid. It is closely related with a welded braid of R. Fenn, R. Rimanyi and C. Rourke. Alexander's and Markov's theorems for virtual knots and braids are proved. Similar results for welded knots and braids are also proved.22 pages, 18 figuresGeometric Topology57M25text