Let (M, g) be a complete Riemannian manifold with no conjugate points and f : (M, g) → (B, gB) a principal G-bundle, where G is a Lie group acting by isometries and B the smooth quotient with gB the Riemannian submersion metric. We obtain a characterization of conjugate point-free quotients (B, gB) in terms of symplectic reduction and a canonical pseudo-Riemannian metric on the tangent bundle T...

1. Statement of results. In this paper we announce a substantial extension of the obstruction theory developed in [ l ] . Detailed proofs and further properties will appear elsewhere. Basically what we have accomplished is to put the theory in [l ] in a more natural setting and extend it to the metastable range. We also apply it to the question of when the Thorn complex JT(£) of a vector bundle...

We study whether sets inside NP can be reduced to sets with low information content but possibly still high computational complexity. Examples of sets with low information content are tally sets, sparse sets, P-selective sets and membership comparable sets. For the graph automorphism and isomorphism problems GA and GI, for the directed graph reachability problem GAP, for the determinant functio...

abstract appendiceal intussusception is a very rare cause of abdominal colic in childhood. this paper reports a reducible appendiceal intussusception in the barium enema in a girl and reviews articles in pubmed.