J., (born 21 July 1937, Yonkers, New York) is an American mathematician, specializing in differential topology, geometric topology, and algebraic topology.He has done research on foliations, knot theory, and 3-manifolds.
In 1974 he found a counterexample to the Seifert conjecture that every non-vanishing vector field on the 3-sphere has a closed integral curve.
In 1995 he demonstrated that Sergei Novikov's compact leaf theorem cannot be generalized to manifolds with dimension greater than 3.
Specifically, Schweitzer proved that a smooth, compact, connected manifold with Euler characteristic zero and dimension > 3 has a C1 codimension-one foliation that has no compact leaf.