Irrational Exuberance (book) Irrational Exuberance (book) Irrational Exuberance is a March 2000 book written by American economist Robert J. Shiller, a Yale University professor and 2013 Nobel Prize winner. The book examines economic bubbles in the 1990s and early 2000s, and is named after Federal Reserve Chairman Alan Greenspan's famed "irrational exuberance" quote warning of such a possible bubble in 1996. Published at the height of the dot-com boom, the text put forth several arguments demonstrating how the stock markets were overvalued at the time. The stock market collapse of 2000 happened the exact month of the book's publication. The second edition of
Proof that π is irrational In 1761, Lambert proved that is irrational by first showing that this continued fraction expansion holds: Then Lambert proved that if "x" is non-zero and rational then this expression must be irrational. Since tan(/4) = 1, it follows that /4 is irrational and therefore that is irrational. A simplification of Lambert's proof is given below. This proof uses the characterization of as the smallest positive number whose half is a zero of the cosine function and it actually proves that is irrational. As in many proofs of irrationality, the argument proceeds by reductio ad absurdum. Consider the sequences ("A") and