Final answer:
A 4-permutation of a set is an ordered arrangement of 4 elements from that set; for example, from set S = {1, 2, 3, 4, 5}, a 4-permutation could be (2, 3, 5, 1) and there are a total of 120 different 4-permutations possible.
Step-by-step explanation:
The concept in question is related to permutations, which falls under the study of combinatorics in mathematics. A 4-permutation of a set is an ordered arrangement of 4 elements from that set. For example, if we have the set S = {1, 2, 3, 4, 5}, one possible 4-permutation could be (2, 3, 5, 1). This example represents a sequence of four numbers chosen from set S, without any repetitions, and where the order matters. In a 4-permutation, the first element can be chosen in 5 ways, the second in 4, the third in 3, and the fourth in 2 ways, leading to a total of 5 x 4 x 3 x 2 = 120 different 4-permutations from set S.