2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/78277We study the Vassiliev knot invariant v_2 of degree 2. We present it via the degrees of maps of various configuration spaces related to a knot to products of spheres. This gives rise to numerous geometrical and combinatorial formulas for this invariant.28 pages, many figuresGeometric TopologyQuantum Algebra57M25text