Brian Kieffer  (2011-06-17)   Marsha Falco's  SET® cards  (1974) What's the probability of having no valid "set" among  9  random cards? The modern  SET®  playing cards form an 81-card deck with a regular ternary structure, used to play a totally new species of games.  It's also a good pretext to practice some challenging  combinatorial calculus.Since 1991, SET decks have been published by  Set Entreprises, a family business now owned and operated by  Colette Falco,  daughter of Marsha and Rober...