👉 In mathematics, a "fikey" is a function that maps a set of numbers into a set of numbers. A fikey is often used in combinatorics and graph theory to represent functions from subsets of a set onto itself or onto other sets, where each element of the input set can be mapped to exactly one output element. For example, consider the set of all ordered pairs (a,b) with 1 <= a <= b <= n. A fikey for this set would map
