Slides from March 23rd updated ¡­

Slides from March 23rd updated due to errors. Three pages replaced by two. Material changes:

• Corrected lambda multiplier (and updated conclusions); I suppose you all know the determinant notation.
• Added an argument why x0=x1 when P risk averse -- it requires S0=S1 (missing from previous version).

Sorry for the inconvenience, and thanks to the student who pointed out the main error.