The A−B slice problem is a reformulation of the topological 4−dimensional surgery conjecture, in terms of smooth decompositions of the 4−ball. This paper applies the theory of link groups of 4−manifolds, recently developed by the author [9], to formulate a candidate for an obstruction in the A − B slice program. The strength of this invariant is illustrated by the theorem that it provides an ob...

In 1990, Cook, Kannan and Schrijver proved that the split closure (the 1st 1-branch split closure) of a polyhedron is again a polyhedron. They also gave an example of a 3-dimensional mixed-integer polytope whose 1-branch split rank is infinite. We generalize this example to a family of high-dimensional polytopes and present a closed-form description of the kth 1-branch split closure of these po...

According to Alexander's law (AL), the slow phase velocity of nystagmus of vestibular origin is dependent on horizontal position, with lower velocity when gaze is directed in the slow compared with the fast phase direction. Adaptive changes in the velocity-to-position neural integrator are thought to cause AL. Although these changes have been described for the horizontal neural integrator, nyst...

We study the dual complexes of boundary divisors in log resolutions of compactifications of algebraic varieties and show that the homotopy types of these complexes are independent of all choices. Inspired by recent developments in nonarchimedean geometry, we consider relations between these boundary complexes and weight filtrations on singular cohomology and cohomology with compact supports, an...