Are the following statements true or false?

 1. The set of all [math]'s that are in the domain of [math] and where [math] is in the domain of [math] correctly describes the domain of [math].

 2. If [math] is an element of the domain of [math], then [math] is an element of the domain of [math].

 3. For any relation [math], it must be that [math] as long as [math] is a constant.

 4. If [math] is in the domain of [math], then [math] is in the domain of [math].

 5. If [math], then [math].

 6. [math] as long as [math] is in both the domain of [math] and in the domain of [math].