In honour of the 65th birthday of Professor M Obata a workshop was held at Keio University. This volume includes notes on the talks and discussions which took place and cover a wide range of subjects on geometry, global analysis, topology and mathematical physics.

In honour of the 65th birthday of Professor M Obata a workshop was held at Keio University. This volume includes notes on the talks and discussions which took place and cover a wide range of subjects on geometry, global analysis, topology and mathematical physics.