Hopf Invariants for sectional category with applications to topological   robotics
  We develop a theory of generalized Hopf invariants in the setting of sectional category. In particular we show how Hopf invariants for a product of fibrations can be identified as shuffle joins of Hopf invariants for the factors. Our results are applied in the study of Farber's topological complexity for 2-cell complexes, as well as in the construction of a counter-example to the analogue for topological complexity of Ganea's conjecture on Lusternik-Schnirelmann category. 
Jes\'us Gonz\'alez, Mark Grant, Lucile Vandembroucq
math.AT