Sect 1.1 Sets and symbols

 

A set is a well-defined collection of objects and each member of a set is called an element.

A set can be specified by a list (roster): {0,1,2,…} or by using set builder notation: {x: x  0} which means “the set of all x greater than or equal to zero”.

 

 

Symbols:

{ }          the set whose members are; denotes a set

Π              is a member/element of; is in the set

A È B   A is a subset of B; everything that is in A is also in B

Æ          the null/empty set; the set that contains no elements; the empty set is a subset of every set.

A = B    the elements in A and B are exactly the same

Ï               is not an element

      Ë           is not a subset

      A Ç B  A intersect B; The elements that A and B have in common

      A È B  A union B; Everything that is in A and B together; do not repeat elements that are the same