Bang Yeol

Bang Yeol (변열) refers to a permutation in Korean combinatorial mathematics. Specifically, it signifies a linear arrangement of elements where the order matters and elements are selected without repetition from a given set. It's the Korean equivalent of the mathematical concept of a permutation.

The number of bang yeols (permutations) of r elements chosen from a set of n elements is denoted as P(n,r) or ₙPᵣ, and is calculated using the formula:

P(n,r) = n! / (n-r)!

where:

• n! represents the factorial of n (n * (n-1) * (n-2) * ... * 2 * 1)
• r is the number of elements being selected and arranged
• n must be greater than or equal to r (n ≥ r)

The term "bang yeol" is typically used within a Korean-speaking mathematical context. In English, "permutation" is the standard and more widely understood term.