Cases in which impurity might have been acquired, in public or private places
Defining the status of a private yard which is also a major thoroughfare: Eruvin 8a, 22b
Status of an alley or path which leads from a public area to a water-holding pit: Eruvin 22b
Cases in which witnesses allege impurity
What happens if witnesses say a person became impure, and he says he did not: Keritot 12a-b