The word blog means web log, and this is my second blog post ever. A ship's logbook is a record for navigation and operation of the ship. Explorers, scientists and doctors have always used logbooks, diaries and journals, knowing that small observations may add up to...

Once upon a time a single cat, incidentally named Pebbles, came to refute a whole theory of cats. The general theory was "All cats are black". Not a very good theory, since Pebbles is a grey cat. The power of a single counterexample is enormous. In mathematics a...