Morphy number

The Morphy number is a measure of how closely a chess player is connected to Paul Morphy (1837–1884) by way of playing chess games. People who played a chess game with Morphy have a Morphy number of 1. Players who did not play Morphy but played someone with a Morphy number of 1 have a Morphy number of 2. People who played someone with a Morphy number of 2 have a Morphy number of 3, et cetera.

The idea is similar to the Erdős number for mathematicians and the Bacon number for actors. For example, Viswanathan Anand, along with many current top players, has a Morphy number of 5: Anand played Efim Geller (Morphy number 4), who played Salo Flohr (Morphy number 3), who played Géza Maróczy (Morphy number 2), who played John Owen (Morphy number 1), who played Morphy. Taylor Kingston states that the idea of the Morphy number may have originated in a June 2000 note by Tim Krabbé, who has Morphy number 4.

As of April 2016, Leonard Barden, Pal Benko, Arthur Bisguier, Melvin Chernev, Dennis Horne, Borislav Ivkov, Erik Karklins, Franciscus Kuijpers, Aleksandar Matanović, Friðrik Ólafsson, Jonathan Penrose, Oliver Penrose, and Peter Swinnerton-Dyer are the only known living players with Morphy number 3.

Many ordinary players have a Morphy number of 6 or less.

These are players who are important in making links for Morphy numbers.

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