Set Theory
set
is a collection of items; these items are
called members
of
the set.
If a set A
has members x,
y, and
z, we
can write A =
{ x,
y, z
} and, for example, x
Î A.
If a set has members defined by a condition, we write A
= {x
| x satisfies
the condition}.
The vertical line is read "such that".
The empty
set (the null
set) is the set containing no items; it is
denoted by Æ or, Æ
= {}.
If all members of a set A
are contained
in a set B,
then A is
a subset of
B ( A
Ì B).
If two sets A
and B contain
the same members, then they are equal (A =
B).