What's the Kennection? #41

What piano contest is named for the Texan who shocked Moscow by winning the first International Tchaikovsky Competition in 1958?

What award, given by the International Mathematical Union since 1936, has been called the "Nobel Prize of Mathematics"?

The Twelfth Amendment, ratified in 1804, fixed procedural problems that had plagued what process?

Canada's Ian Miller, a two-time winner of the Show Jumping World Cup, is the only person to participate in what event ten times?

In The Pirates of Penzance, Frederic is told he must serve the pirates for 63 more years, because his birthday happens to fall on what date?

What's the "Kennection"?