Seminar problem, updates, corrections

• Seminar problems uploaded
• Concave/quasiconcave functions factsheet corrected (the C1 criteria where I managed to turn everything on its head) and updated with few lines bottom first page, and a fourth page on nonlinear programming.
• The totally optional note on complex numbers had confused "eigenvectors" with "eigenvalues". Corrected.

After Easter: 

• How to destroy Lagrange/Kuhn-Tucker
  • "Application" of this and of concave programs: why you so often see "minimize risk for given expected return" rather than "maximize expectation for given risk" in textbooks.
• The Bernoulli first-order differential equation.