Computability
... [Note: Sipser uses size.] Georg Cantor (1873) noticed that two finite sets are the same size if the elements in each can be paired. Definition: Two sets A & B have the same cardinality (size?) if there exists a function f: A → B, that is 1 to 1 and onto 1 to 1 means: if f(a) = f(b) then a=b. onto me ...
... [Note: Sipser uses size.] Georg Cantor (1873) noticed that two finite sets are the same size if the elements in each can be paired. Definition: Two sets A & B have the same cardinality (size?) if there exists a function f: A → B, that is 1 to 1 and onto 1 to 1 means: if f(a) = f(b) then a=b. onto me ...