is then based on realizing as a topological 1-group. this way one trades the 2-group for a topological 1-group, and all levels in the construction of Spin(n) are lowered by one. and since the model for is a Lie 1-group, one can wonder (and actually succeed in finding) whether Sting(n) can be realized as a Lie 2-group. at the topological lever one can iterate the lower the base step trick, i.e. o