Lesson 2

In this lesson, we will formulate several basic rules, each of which, on the one hand, is obvious, and on the other hand, is used in almost every calculation.

Sum Rule: If there are \(n\) objects of the first type and \(k\) objects of the second type, then there are \(n+k\) objects in total. In terms of set theory: if sets \(A\) and \(B\) are disjoint, then \(|A \cup B|=|A|+|B|\).

first_set = {'e', 'u'}
second_set = {8, 2, 5}

print(first_set | second_set)

{2, 5, 'u', 'e', 8}

For the piece on the chessboard (that goes one cell up or to the right), it takes 14 moves to get from the bottom-left corner to the top-right corner: seven moves up and seven moves to the right. (Note that the answer for the previous problem may be entered both as \(\texttt{14}\) and \(\texttt{7+7}\).)