x Abu Dhabi, UAESaturday 22 July 2017

# The Lewis Carroll expert

Float through any social event with M's fast facts. This week John Mather explains Lewis Carroll.

Float through any social event with M's fast facts. This week John Mather explains Lewis Carroll THE BASICS Charles Lutwidge Dodgson, better known as Lewis Carroll, the author of Alice's Adventures In Wonderland, was a mathematician. As a result, the book is filled with maths and logic. Tim Burton's film version of the classic story is on release this week. THE AUTHOR Dodgson was a professor of mathematics at Oxford University, specialising in logic, geometry and algebra. He published many books on the topics, notably The Game Of Logic and Euclid And His Modern Rivals. THE MATHS In chapter one of Alice's Adventures In Wonderland, Alice, after drinking a shrinking potion, contemplates the concept of limits. Namely, how small can she get? Later, she does some strange multiplication, saying that "four times five is 12". This is, in fact, correct when using the base 18. What that means is for another instant expert altogether. She tackles logic problems with the Mad Hatter, who points out that "I see what I eat" is not the same "I eat what I see". Finally, the Cheshire Cat shows that the contrapositive of a true statement is also true. If Alice accepts that a dog - which growls when angry and wags its tail when happy - is not mad, then the Cheshire Cat, which does the opposite, must be mad. THE CONVERSATION Dodgson created many logic puzzles, where a few statements lead to an inescapable conclusion. Try to determine the logical result of these three statements (the contrapositive rule will help): 1) No ducks waltz; 2) No officers decline to waltz; 3) All my poultry are ducks.