Hadamard manifold
In mathematics , a Hadamard manifold , named after Jacques Hadamard — more often called a Cartan–Hadamard manifold , after Élie Cartan — is a Riemannian manifold ( "M" , "g" ) that is complete and simply connected and has everywhere non-positive sectional curvature . 
<triplet> Jacques Hadamard <subj> mathematics <obj> field of work