2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/222803We describe a construction of an object associated to the fundamental group of the projective line minus three points in the Bloch-Kriz category of mixed Tate motives. This description involves Massey products of Steinberg symbols in the motivic cohomology of the ground field.37 pagesAlgebraic GeometryK-Theory and Homology14C25; 19E15text