convenient form without changing its overall meaning. Today, this way of looking at
logic is called Boolean algebra. (For more information about Boole, see “History of
Mathematics.”)
Boolean algebra did not end there: In 1881 the English logician and mathematician
John Venn (1834–1923) interpreted Boole’s work and introduced a new way of diagram-
ming Boole’s notation in his treatise Symbolic Logic. This was later refined by the Eng-
lish mathematician Charles Dodgson (1832–1898), who was better known as the writer
of Alice’s Adventures in Wonderland(under the pseudonym Lewis Carroll). Today, when
studying sets, we call this method not the Boole, Carroll, or Dodgson diagram, but the
Venn diagram. Thus, Boolean notation demonstrates the relationship between groups,
indicating what is in each set alone, what is jointly contained in both, and what is pre-
sent in neither.