Before revision: The second order denominator term is equal to: where the second form is the often used shorthand notation for a sum that does not repeat permutations (e.g., only one of the permutations and are counted .
After revision: )The second order denominator term is equal to: where the second form is the often used shorthand notation for a sum that does not repeat permutations (e.g., only one of the permutations and are counted .