We show that for n ≥ 3 there is an action of the braid group Bn on the determinantal ideals of a certain n × n symmetric matrix with algebraically independent entries off the diagonal and 2s on the diagonal. We show how this action gives rise to an action of Bn on certain compact subspaces of some Euclidean spaces of dimension n 2 . These subspaces are real semi-algebraic varieties and include ...
