i 11.30 Telecommunications Networks
The size of telephone exchanges has been a problem for over 100; years. It is possible to connect every subscriber with every other subscriber directly - but this is inefficient. Optimisation is necessary.

11.55 Unemployment in the 1930s
How did the slump of the 1930s affect economic thinking? John Maynard Keynes's General Theory proposed a new role for government in stimulating demand, and Roosevelt's New Deal put some of his principles into practice.