Gilbreath Principle

Gilbreath Principle is the fact that when a sequence (which may or may not be a repeating sequence) is riffle shuffled into its reverse, there are certain properties of the mixed outcome that are mathematically guaranteed.

The observation was analyzed and documented by Norman Gilbreath and first described in The Linking Ring, Vol. 38, N° 5, July 1958, page 60 under Magnetic Colors.

Eight years later, in June 1966 Linking Ring, he published a generalization, extending his first observation from the case n = 2 to arbitrary n, which is referred to as the Second Gilbreath Principle.