Exercise $4.$ Given the following ER diagram $($see exercise $2$ of homework $1)$

Exercise $1.$ Consider the instance of the Students relation shown in the following table

a$)$ Give an example of an atribute $($or set of attributes$)$ that you can deduce is not a candidate key, based on this

instance being legal

b$)$ Is there any example of an atribute $($or set of atributes$)$ that you can deduce is a

candidate key, based on this instance being legal?

Exercise $2.$ Consider the following relations:

Roous$(rvar$ integer. olfres string. caparige integer$)$

Earolled $(sut$ string. cat string. gode string$)$

Teaches$(ode$ swing. codt swing$)$

$Meet{s}_{\text{I}}$nccist swring. tho: integer, himer suring

a$)$ List all the foreign key constraints among these relations.

b$)$ Give an example of a $($plausible$)$ constraint involving one or more of these relations that is not a primary

key or foreign key constraint.

Exercise $3.$ Given the following ER diagram $($see exercise $1$ of homework $1)$

Translate it into a relational schema. If there are constraints that cannot be captured by your translation, explain

why.