Discrete Mathematical Structures, Lecture 1.3: Permutations and combinations

Discrete Mathematical Structures, Lecture 1.3: Permutations and combinations.

We begin this lecture with a number of various counting problems, from easy too difficult. One that we study in more details is how many ways there to arrange k objects chosen from a group of n -- this is called a permutation, and denoted P(n,k). Similarly, we can ask how many ways there are to simply choose k objects from a group of n. This is called a combination, and denoted C(n,k); way say "n choose k". It is like a permutations but order does not matter, and so we get the relation that P(n,k) = k! C(n,k).

[Elise.]

Love this series. Thank you for posting it!