part i
research the term primary key. discuss what this means in the context of functions and relations. describe an example of the use of a primary key.
part ii
consider the example of the states of the united states and the senators of the united states. if you consider the set of states as a domain and the set of senators as a range, you can establish a relation based on associations between the senators and the states. this relation would not be a function because each state corresponds to more than one senator. however, if you reverse the roles of the domain and range, then the relation is a function because each senator is associated with only one state.
make up your own example of 2 real-world sets