Theorem
A product of connected spaces is connected.
Proof
Let be a collection of connected spaces and let
be a collection of connected spaces and let be the product space.
be the product space.
Let and let
and let be the component to which
be the component to which belongs.
belongs.
Take and let
and let be any open set containing
be any open set containing
The set is homeomorphic to
is homeomorphic to hence is connected.
hence is connected.
Since where
where is the component of
is the component of
The set hence
hence
Then has one component and is connected.
has one component and is connected.