Constraints in the lambda_0-Omega_0 plane from gravitational lensing
  I review simultaneous constraints on the cosmological parameters lambda_0 and Omega_0 from gravitational lensing. The emphasis is on systematic extragalactic surveys for strong gravitational lenses, mainly the largest and best-defined such survey, JVAS/CLASS. 
Phillip Helbig (University of Groningen, Kapteyn Astronomical   Institute, The Netherlands)